CA1248138A - Method for the preparation of 2-(trifluoro- methyl)phenyl carbamic fluoride - Google Patents
Method for the preparation of 2-(trifluoro- methyl)phenyl carbamic fluorideInfo
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- CA1248138A CA1248138A CA000549081A CA549081A CA1248138A CA 1248138 A CA1248138 A CA 1248138A CA 000549081 A CA000549081 A CA 000549081A CA 549081 A CA549081 A CA 549081A CA 1248138 A CA1248138 A CA 1248138A
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- fluoride
- trifluoromethyl
- anthraniloyl
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Abstract
ABSTRACT
A method for the preparation of a 2-(trifluoro-methyl)-phenyl carbamic fluoride comprises isomerizing N-(trifluoromethyl)-anthraniloyl fluoride in the presence of hydrogen fluoride to 2-(trifluoromethyl)phenyl carbamic fluoride.
A method for the preparation of a 2-(trifluoro-methyl)-phenyl carbamic fluoride comprises isomerizing N-(trifluoromethyl)-anthraniloyl fluoride in the presence of hydrogen fluoride to 2-(trifluoromethyl)phenyl carbamic fluoride.
Description
This invention relates to a method for the preparation of phenyl carbamic fluorides, useful in the preparation of benzenamines.
This Application is a divisional Application of Canadian Patent Application S.N. 455,705, filed June 1, 1984.
The benzenamines, also known as anilines and as amino-benzenes, are a known class of compounds having commerclal utility as chemical intermediates, for a wide range of chemical end products. Substituted benzenamines, especially trifluoro-methyl-substituted benzenamines such as 2-ttrifluoromethyl)-benzenamines (also known as o-trifluoromethyl anilines or o-aminobenzotrifluoridesJ are particularly useful as inter-mediates for the preparation of various dyestuff and pesticides. For example, 2-amino-5-chlorobenzotrifluoride (also known as 4-chloro-2-(trifluoromethyl)benzenamine), is employed commercially as a dye intermediate and is designated as C.I. Azoic Diazo Component 17, according to Colour Index, Chemical No. 37055, Vol. 1-4, 2nd ed. 1956, Suppl. 1963 published by the Society of Dyers and Colourists (U.K.) and - 20 The American Association of Textile Chemists and Colorists (U.S. ) .
~1 ~2~38 Substituted benzenamines, such as (trifluoromethyl)-benzenamines are disclosed in U.S. Patent 4,243,819 to Henrick et al., as intermediates in the synthesis of amino acid esters having pesticidal properties. Thus, for examplei the reference teaches the preparation of such esters by reaction of various trifluoromethylanilines with m-phenoxybenzyl ~-bromoiso-valerate.
U.S. Patent 4,316,988 to Clinton discloses the use of trifluoromethyl-substituted anilines as intermediates in the ~ 10 synthesis of various diphenylamine products useful as rodenticides, insecticides, and arachnicides.
The utility of benzenamines, including o-aminobenzotri-fluorides as chemical intermediates has led to the investiga-tion and development of various methods for the preparation of these compounds.
One known method for the preparation of aromatic amines, such as aniline, involves the reduction of an aromatic nitro compound. Thus, aniline may be prepared by reaction o~
nitrobenzene with hydrogen. McBee et al., J. Am. Chem. Soc.
73, 3932-34 (19~1) disclose the preparation of 4-bromo-2-(tri-fluoromethyl)-aniline by nitration of 3-bromo-(trifluoro-methyl)-benzene followed by reduction of the resultant
This Application is a divisional Application of Canadian Patent Application S.N. 455,705, filed June 1, 1984.
The benzenamines, also known as anilines and as amino-benzenes, are a known class of compounds having commerclal utility as chemical intermediates, for a wide range of chemical end products. Substituted benzenamines, especially trifluoro-methyl-substituted benzenamines such as 2-ttrifluoromethyl)-benzenamines (also known as o-trifluoromethyl anilines or o-aminobenzotrifluoridesJ are particularly useful as inter-mediates for the preparation of various dyestuff and pesticides. For example, 2-amino-5-chlorobenzotrifluoride (also known as 4-chloro-2-(trifluoromethyl)benzenamine), is employed commercially as a dye intermediate and is designated as C.I. Azoic Diazo Component 17, according to Colour Index, Chemical No. 37055, Vol. 1-4, 2nd ed. 1956, Suppl. 1963 published by the Society of Dyers and Colourists (U.K.) and - 20 The American Association of Textile Chemists and Colorists (U.S. ) .
~1 ~2~38 Substituted benzenamines, such as (trifluoromethyl)-benzenamines are disclosed in U.S. Patent 4,243,819 to Henrick et al., as intermediates in the synthesis of amino acid esters having pesticidal properties. Thus, for examplei the reference teaches the preparation of such esters by reaction of various trifluoromethylanilines with m-phenoxybenzyl ~-bromoiso-valerate.
U.S. Patent 4,316,988 to Clinton discloses the use of trifluoromethyl-substituted anilines as intermediates in the ~ 10 synthesis of various diphenylamine products useful as rodenticides, insecticides, and arachnicides.
The utility of benzenamines, including o-aminobenzotri-fluorides as chemical intermediates has led to the investiga-tion and development of various methods for the preparation of these compounds.
One known method for the preparation of aromatic amines, such as aniline, involves the reduction of an aromatic nitro compound. Thus, aniline may be prepared by reaction o~
nitrobenzene with hydrogen. McBee et al., J. Am. Chem. Soc.
73, 3932-34 (19~1) disclose the preparation of 4-bromo-2-(tri-fluoromethyl)-aniline by nitration of 3-bromo-(trifluoro-methyl)-benzene followed by reduction of the resultant
2-nitro-5-bromo(trifluoromethyl)-benzene.
U.S. Patent 4,096,185 to Seiwell discloses the preparation of p-aminobenzotrifluoride ~also known as q-(trifluoromethyl)-benzenamine) by reaction of p-chlorobenzotrifluoride with ammonia in a non-aqueous solvent in the presence of copper ~ 3~
compound, such as cuprous chloride and a selected salt, such as potassium fluoride.
Forbes et al., Tetrahedron, Vol. 8, 67-72 (1960) prepared D-aminobenzotrifluoride by hydrogenation of 2-nitrotri~luoro-methylbenzene at elevated temperatures and pressure in thepresence of a Raney nickel catalyst.
German Offenlegungschr;ft D.E. 3,017,542 to Klauke et al.
discloses the preparation of o-aminobenzotrifluoride by hydrogenation-hydrogenolysis of 2-amino-5-chlorobenzotri-- 10 fluoride.
It is also known that isocyanates and carbamic acid fluorides are susceptible to hydrolysis, in a known manner, to form an amine. See Fieser and Fieser, Organic Chemistry, 3rd Ed D.C. Health and Co. (1956). However, when the reaction is run neat, substantial quantities of urea may be formed as by-product. The formation of urea may be minimized, or avoided when a solvent, such as toluene, is employed, but the yields of amine are low.
. . .
Although methods for the preparation of aromatic amines, such as aminobenzotrifluorides are known from the prior art, it will be appreciated that the development of improved and more economical processes is desirable.
The present process for the preparation of benzenamines differs substantially from the prior art processes in ~he use of hydrogen fluoride and phenyl carbamic fluorides as reactants. Furthermore, the preparation of 2-(trifluoro-~2'~38 methyl)phenyl carbamic fluorides in accordance with this invention, differs substantially from the prior art processes.
The preparation of the phenyl carbamic fluorides by reaction of phenyl isocydnates and hydrogen fluoride is known. Buckley et al. J. Chem. Soc. 864 (1945) disclose the preparation of phenyl carbam;c ac;d fluorides by reaction of HF with various isocyanates. HoweYer, the reference provides no teaching relative to the fluorinat;on of aromatic isocyanates bearing a haloalkyl s;de chain and no teaching or suggestion of the preparation of aromatic amines. The reference further discloses the treatment of phenylcarbamyl fluoride with water to result ;n the formation of diphenylurea.
British Patent 955,898 (1964) to Farbenfabriken Bayer Aktiengesellschaft discloses the reaction of anhydrous hydrogen fluoride w;th chloromethylphenyl isocyanates to produce the - corresponding fluoromethylphenyl carbamic acid fluoride, or, upon subsequent heating, the corresponding isocyanate. The British patent further discloses the reaction of hydrogen .
fluoride with 2-trichloromethyl-4-chlorophenyl isocyanate in chlorobenzene to prepare 2-trifluoromethyl-4-chlorophenyl carbam;c acid fluor;de. Subsequently, Klauke, Angew. Chem.
Interat. Ed. Vol. 5, No. 9, 848, (1966), in contrast to the teachings of Brit. Pat. 955,898, stated that when o-trichloro-methylphenyl isocyanate undergoes chlor;ne-fluorine exchanye in anhydrous hydrogen fluoride; isomerization occurs simul-~ 3~L3~3 taneously and o-N-(trifluoromethyl)aminobenzoyl fluoride can be isolated, thus implying that o-trifluoromethyl phenyl carbamic acid fluoride is not produced. In U.S. Patent 3,829,460 to Buttner and Klauke assigned to Bayer Aktiengesellschaft, reference is made to the 1966 article and to earlier contradictory teachings and it is disclosed that when hydrogen fluoride is reacted with a trichloromethylphenyl isocyanate wherein the tr;chloromethyl group is in the 2-position to the isocyanate group, it is only possible to obtain the isomers, ;_ 2-N-trifluoromethylamino-benzoyl fluorides.
British Patent 1,164,223 to Klauke et al. teaches the hydrolysis of trifluoromethylphenyl isocyanates with 90-100 percent sulfuric acid to produce the corresponding trifluoro-methyl benzenamine (or amino sulfate) with carbon dioxide as the only byproduct.
The hydrolysis of an NC0 group with acid agents, such as concentrated hydrochloric acid or sulphamic acid is known (Houben-Weyl, Methoden der org. Chemie, 4th Edition, Vol. 11/1, page 953).
Although the utility and commercial value of aromatic amines has been generally recoyni~ed for many years; and, various investigations have been made of reactions of aromatic isocyanates, including aromatic isocyanates, including aromatic isocyanates having a perchlorinated alkyl side chain, there has been no suggestion heretofore that aromatic amines can be prepared by the reaction of hydrogen fluoride with phenyl ~Z 9~ 3~3 carbamic acid fluorides or their precursor phenyl isocyanates.
Furthermore, it has not been known heretofore that 2-(tri-fluoro-methyl)phenyl carbamic fluorides may be conveni~ntly prepared by the isomerization of N-(trifluoromethyl)-anthraniloyi fluorides in the presence of hydrogen fluor;de.
It has now been found that benzenamines, of the formula ~lNH2)q , 10 Rm~ln wherein R is chlorinel fluorine, bromine, phenyl, chlorophenyl, fluorophenyl, or bromophenyl Y is trifluoromethyl or difluoromethyl m is O to 2 ` n is O to 2 , q is 1 to 2 and their hydrofluoride complexes can be prepared by ,.o (A) reacting hydrogen fluoride with a phenyl carbamic fluoride of the formula . ~ NHCOF)q Rm ~ - Xn . . . -, .g~38 where q, m, n, and R are as defined above, and X is trichloromethy~, tribromomethyl, trifluoromethyl, dichloromethyl, dibromomethyl or difluoromethyl with the provision that when X i5 trichloromethyl t tribromomethyl or trifluoromethyl, Y is trifluoromethyl and when X is dichloromethyl, dibromomethyl or d;fluoromethyl, Y is difluoromethyl, to produce a benzenam;ne hydrofluoride complex; of the formula ~ NH2'ZHF)q .. 10 Rm--~Yn where z is about 1 to about 4 and R, Y, q, m and n are as defined above; and, when desired, (B) dissociating the benzenamine~hydrofluoride complex and recovering the benzenamine.
The benzenamine'hydrofluoride resulting from the reaction of hydrogen fluoride with the phenyl carbamic fluoride in accordance with step (A), above, is a complex of variable stoichiometry. The explanation of the variable stoichiometry of these benzenamine'hydrofluoride complexes is not essential to the process of th~s invention or the preparation or use of such complexes. However, it may be postulated that the variable stoichiometry is a result of hydrogen bonding.
The amine'HF complex can be dissociated by heating for example, to temperatures above 100 Celsius. However, at such temperatures the dissociation may be accompanied by undesirable ~ L3~3 reactions such as polymerization. In a preferred manner, the benzenamine'hydrofluoride complex can be readily dissociated by conventional methods such as neutralization with caastic or the like, and the benzenamine recovered from the reaction mixture by conventional physical separation processes such as distillation or the like. The neutralization of amine'hydro-fluorides with KOH, NaOH or the like is disclosed by Berliner et al., Journal of Physical Chemistry, Yol. 32, 1142-1162, (1928).
0 Generally for the reaction of hydrogen fluoride with the phenyl carbamic fluoride, a temperature in the range of about -10 to about 150 Celsius and preferably about 2~ to about 100 Celsius is employed. The reaction may be run neat or in the presence of a carrier medium, such as methylene chloride.
The reaction proceeds smoothly, without the need for a catalyst. However, if desired, a catalyst~ such as a Lewis acid catalyst may be employed.
The reaction of the phenyl carbamic acid fluoride with hydrogen fluoride is carried out in ~he presence of a stoichiometric excess of hydrogen fluoride to result in the formation of the benzenamine'hydrofluoride and carbonyl fluoride as a by-product. The amount of hydrogen fluoride provided to the reaction should be at least slightly in excess of the amount required for the formation of the benzen-amine'hydrofluoride. Preferably the amount of hydrogen fluoride will be sufficient to provide a molar ratio of ~L~ 3 8 hydrogen fluoride:phenyl carbamic fluoride of between 4:1 and 30:1 or greater. It is preferred to carry out the reaction in the liquid phase either in a sealed reactor, that is, an autoclave, Pr at atmospheric pressure, using a cooling condenser~
The phenyl carbamic fluoride reactant may be conveniently prepared by reaction of the corresponding phenyl isocyanate with hydrogen fluoride. The reaction may be carried out in the liquid or vapor phase. In the liquid phase the reaction may be carried out at atmospheric pressure, with the temperature being maintained at below the boiling point of hydrogen fluoride9 or at higher pressures and temperatures under autogenous conditions. It is preferred to carry out the reaction neat.
However, if desired, a carrier medium such as methylene chloride may be employed. ~ypically, ~or a liquid phase reaction, temperatures in the range of about 20 to about 100 Celsius are e~ployed. In a vapor phase reaction the tempera-- ture will generally be above the boiling point of the reaction mixture with no practical upper limit. Typically, the vapor phase reaction is run at a temperature o~ about 250~ to about 350 Celsius. It is preferred to carry out the reaction with at least slight stoichiometric excess of hydrogen fluoride present at all times. Although there is no practical upper limit to the molar ratio of hydrogen fluoride to organic reaction employed, a ratio between absut 5:1 and about 25:1 is generally employed.
~2~ 3~
It has been found that when hydrogen fluoride is reacted with a l-isocyanato-2-(trihalomethyl)benzene to prepare a 2-(trifluoromethyl)phenyl carbamic fluoride, the in si~u formation of N-(trifluoromethyl)-anthraniloyl fluoride occurs S during the reaction. The anthraniloyl fluoride may be isolated and recovered. However, if left under reaction conditions, a rearrangement or isomerization of the N-(trifluoromethyl)phenyl carbamic fluoride is formed. This intermediate formation of an N-(trifluoromethyl)anthraniloyl fluoride and the isomeriza-~ 1~ tion thereof has only been found in reactions involving orthotrihalomethyl-substituted phenyl isocyanates, such as l-isocyanato-2-(trihalomethyl)benzene and ring substituted derivatives, and does not appear to occur in reactions involving meta- or para-trihalomethyl-substituted phenyl isocyanates.
Thus, in accordance with ~he px~s~t invention, it has been found that 2-(trifluoromethyl)phenyl carbamic fluorides of the formula ~F3 Xn ~ NHCOF
~L2 ~3~ 3~
where n is O to 2 and X is independently selected from the group fluoro-, chloro-, bromo-, phenyl-, chlorophenyl-, bromophenyl-, and fluorophenyl- can be prepared by isDmerizing an N-(trifluoromethyl)-anthraniloyl fluoride of the formula ~OF
Xn ~ NHCF3 where n and X are as defined above, in the presence of hydrogen _ fluoride.
The isomerization of N-(trifluoromethyl)-anthraniloyl ~luoride to 2-(trifluoromethyl)phenyl carbamic fluoride proceeds readily in the presence of hydrogen fluoride.
Preferably, the hydrogen fluoride is present in an amount of about 1.5 to about 25 and most preferably about 4.0 to about 20.0 moles of hydrogen fluoride per mole of N-(trifluoro-methyl)-anthraniloyl fluoride. When lesser amounts are employed the isomerization will occur, but the reaction time is ., .
much longer. Greater amounts of hydrogen fluoride may be employed, but provide no special advantage.
It is preferred to carry out the isomerization in the liquid phase. The process may be carried out at atmospheric pressure, with the temperature being maintained at or below the 2~ boiling point of hydrogen fluoride, or at higher pressures and temperatures under autogenous conditions. Temperatures, for ~L~ L3~3 example, in the range of about -lO~ or less to about 150 Celsius or higher may be employed. Preferab~y, temperatures in the range of about 2~ to about lOOD Celsius are employed.
The rea.ction may be run neat or in the presence of a carrier medium such as methylene chloride. The reaction proceeds smoothly without the need for a catalyst. However, if desired, a catalyst, such as a Lewis acid catalyst, such as antimony pentachloride, may be employed.
The reactants susceptible to isomerization in accordance '~ lO with this invention include N-(trifluoromethyl)-anthraniloyl fluoride as well as the various derivatives bearing ring-substituents9 such as, fluoro-, chloro-, bromo-, phenyl-, chlorophenyl-, fluorophenyl-, or bromophenyl-. The isomerization of N-(trifluoromethyl)-anthraniloyl fluoride to 2-(trifluoromethyl)-phenyl carbamic fluoride is of particular interest due to the utility of the latter as an intermediate for the subsequent preparation of 2-(trifluoromethyl)-benzen-amine.
N-(trifluoromethyl)-anthraniloyl fluoride may be 2~ conveniently prepared by the reaction of 1-isocyanato-2-(tri-chlorom~thyl)-benzene. The reaction may be carried out in the liquid or vapor phase. In the liquid phase the reaction may be carried out at atmospheric pressure, with the temperature being maintained at or below the boiling point of hydrogen fluoride, or at higher pressures and temperatures under autogenous conditions. Typically for a liquid phase reaction, ~ 3~
temperatures in the range of about -10 to about 100~ Celsius are employed. In a vapor phase reaction the temperature will ~enerally be above the boiling point of the reaction m~ture with no practical upper limit. Typically, the vapor phase reaction is run at a temperature of about 250 to about 350 Celsius.
It is preferred to carry out the reaction of the 1-isocyanato-2-(trichloromethyl)-benzene and hydrogen fluoride with at least a slight stoichiometric excess of hydrogen f- lo fluoride present at all times. Although there is no theoretical upper limit to the molar ratio of hydrogen fluoride to organic reaction employed, a ratio between about 4:1 and about 2~:1 is generally employed. The reaction may be run neat or in the presence of a carrier medium such as methylene chloride.
The N-(trifluoromethyl)-anthraniloyl fluoride reactant may be employed in substantially pure form or, cGnveniently, as the crude reaction product of hydrogen fluoride and 1-isocyanato-2-(trichloromethyl)-benzene as described in the preceding paragraph. Thus, in one embodiment, the present invention provides a process for the preparation of 2-(trifluoromethyl)-phenyl carbamic fluoride comprising (A) reacting 1-isocyanato-2-(trichloromethyl)-benzene with hydrogen fluoride to form N-(trifluoromethyl)-anthraniloyl fluoride; and (B~ isomerizing the N-(trifluoromethyl)-anthraniloyl fluoride in the presence of hydrogen fluoride to form 2-(trifluoromethyl)phenyl carbamic fluoride.
The 2-(trifluoromethyl)phenyl carbamic fluoride resulting from the isomerization step of this invention may be recovered from the crude reaction product in relatively pure form by convention~l physical separation means, such as distillation.
Alternatively, if the 2-~trifluoromethyl)phenyl carbamic fluoride is to be employed as a chemical intermediate for the preparation of 2-(trifluoromethyl)-benzenamine, or the hydro-fluoride salt thereof, it may be employed in the crude form, without purification or separation from the reaction mixture.
~~ In this instance, the crude 2-(trifluoromethyl)phenyl carbamic fluoride product of the isomerization step is further reacted with hydrogen fluoride to form the hydrofluoride salt or complex of 2-(trifluoromethyl)-benzenamine.
Thus, the phenyl carbamic fluoride reactant may be employed in substantially pure form or as the crude product of the reaction of hydrogen fluoride and a phenyl isocyanate prepared as described above. Thus, in one aspect, this - invention provides a process for the preparation of benzenamine which comprises reacting a phenyl isocyanate with 20 ~ hydrogen fluoride to form a phenyl carbamic acid fluoride and continuing the reaction of the phenyl carbamic acid fluoride with hydrogen fluoride to produce the benzenamine.
In another aspect of the present invention, it has been found surprisingly that the reaction of a phenyl carbamic fluoride with hydrogen fluoride to form the benzamine hydro-fluoride, may be accelerated by the addition of water to the ~ 3~
reaction mixture. The amount of water added to the reaction mixture is not critical and will be effective even in trace amounts. Typically, the amount of water employed will~be in the range ~f about 0.001 to about 2.0 moles of water per mole of phenyl carbamic fluoride. Thus, in a preferred embodiment of this invention, the reaction of hydrogen fluoride with phenyl carbamic fluoride is carried out in the presence of 4 to about 30 moles of hydrogen fluoride per mole of phenyl carbamic fluoride, and in the further presence of about 0.001 to about 2.0 moles of water per mole of phenyl carbamic fluoride to form the corresponding benzenamine hydrofluoride.
The follo~ing specific examples are provided to further illustrate this invention and the manner in which it may be carried out. It will be understood, however, that the specific details given in the examples have been chosen for purpose of illustration and are not to be construed as a limitation on the invention. In the examples, unless otherwise indicated, all parts and percentages are by weight and all temperatures are in degrees Celsius.
Examples 1 6 - Preparation of 2-(Trifluoromethyl)Benzenamine from 2-(Trifluoromethyl)Phenyl Carbamic Fluoride Example_l Three hundred and two parts of 2-(trifluoromethyl)phenyl carbamic fluoride was charged to a polytetrafluoroethylene reaction Yessel and maintained at 0C while 420 parts of liquid ~8~
hydrogen f1uoride was added. The reaction vessel was then sealed and the temperature was increased to about 20~C and maintained thereat, with agitation, for about 16 hours; The reaction vessel was then opened to atmospheric pressure.
Analysis of the organic liquid reaction product by gas chromatographic techniques indicated 54.6% 2-(trifluoromethyl)-phenyl carbamic fluoride starting material.
Example 2 2-(Trifluoromethyl)phenyl carbamic fluoride was prepared in situ by the reaction of 1~7 parts of 1-isocyanato-2-~tri-fluoromethyl)benzene and 336 parts of hydrogen fluoride added over a 15 minute period at 0C. Eighteen p~rts of water was added to the 2-(trifluoromethyl)phenyl carbamic fluoride reaction product and the temperature was increased to about 60DC. The temperature was maintained thereat while hydrogen fluoride was continually refluxed and returned to the reaction mixture. After 24 hours, analysis of the liquid reaction mixture, using gas chromatographic techniques, indicated that . .
the organic reaction product contained 99 percent 2-(tr;fluoro-methyl)benzenamine and 1.0 percent 2-(trifluoromethyl)phenyl carbamic fluoride.
The liquid reaction product is made alkal;ne by addit;on of NaOH and distilled under reduced pressure to recover 2-(tri-fluoromethyl)benzenamine.
Examples 3-6 The procedure of Example 2 was repeated except that conditions were varied as shown, with the results as set forth in Table 1, below.
~Z~ .3 - ~7 ' ...
.~1 E E
C o ~ . ~
~ _ -o ~
~ ~ r~
L~
_ L C
f : .,, E
D c . cr. ~ N
L ~ cr ~ er O~ N
O _ ~ O~ et N
~ al ~c -I
LL
_ ~
~S L~ L
CL ~ u~
., _ r-4 _I
.~
~ O ~ ~ O ~ C~
L .~ r ~ t~ C
~ .~ v~
a, ' E E ' E ~
L
_ a ~ ~ ~ C
1~
e o Cl~ _ ~8g~ 38 Example 7 - Preparation of 2-~rifluoromethyl)Benzenamine 2-(Trifluoromethy1)phenyl carbamic fluoride was prepared in situ by the reaction of 515 parts of 1-isocyanato-2:(tri-chloromethyl)benzene and 1015 parts of hydrogen fluoride added over a per;od of about 2 hours at a temperature of about 0~-4~C. The reaction mixture WdS then sealed in a polytetrafluoroethylene reactor heated to about ~4C and maintained thereat, with agitation, ~or about 48 hours. The reactor was then opened and equipped with a cooling condenser.
! ~0 Thirty-nine parts of water was added and the reaction mixture was stirred at atmospheric pressure for about 48 hours. The reactor was then opened and equipped with a cooling condenser.
Thirty-nine parts of water was added and the reaction mixture was stirred at atmospheric pressure for 120 hours. The reaction mixture was then swept with nitrogen to remove hydrogen fluoride, and rendered alkaline by slow addition of 305 parts of 20~ aqueous sodium hydroxide, washed with methylene chloride, then distilled under reduced pressure to yield 293 parts of 2-(trifluoromethyl)benzenamine.
~0 Example 8 - Preparation of 3-(Trifluoromethyl)Ben2enamine
U.S. Patent 4,096,185 to Seiwell discloses the preparation of p-aminobenzotrifluoride ~also known as q-(trifluoromethyl)-benzenamine) by reaction of p-chlorobenzotrifluoride with ammonia in a non-aqueous solvent in the presence of copper ~ 3~
compound, such as cuprous chloride and a selected salt, such as potassium fluoride.
Forbes et al., Tetrahedron, Vol. 8, 67-72 (1960) prepared D-aminobenzotrifluoride by hydrogenation of 2-nitrotri~luoro-methylbenzene at elevated temperatures and pressure in thepresence of a Raney nickel catalyst.
German Offenlegungschr;ft D.E. 3,017,542 to Klauke et al.
discloses the preparation of o-aminobenzotrifluoride by hydrogenation-hydrogenolysis of 2-amino-5-chlorobenzotri-- 10 fluoride.
It is also known that isocyanates and carbamic acid fluorides are susceptible to hydrolysis, in a known manner, to form an amine. See Fieser and Fieser, Organic Chemistry, 3rd Ed D.C. Health and Co. (1956). However, when the reaction is run neat, substantial quantities of urea may be formed as by-product. The formation of urea may be minimized, or avoided when a solvent, such as toluene, is employed, but the yields of amine are low.
. . .
Although methods for the preparation of aromatic amines, such as aminobenzotrifluorides are known from the prior art, it will be appreciated that the development of improved and more economical processes is desirable.
The present process for the preparation of benzenamines differs substantially from the prior art processes in ~he use of hydrogen fluoride and phenyl carbamic fluorides as reactants. Furthermore, the preparation of 2-(trifluoro-~2'~38 methyl)phenyl carbamic fluorides in accordance with this invention, differs substantially from the prior art processes.
The preparation of the phenyl carbamic fluorides by reaction of phenyl isocydnates and hydrogen fluoride is known. Buckley et al. J. Chem. Soc. 864 (1945) disclose the preparation of phenyl carbam;c ac;d fluorides by reaction of HF with various isocyanates. HoweYer, the reference provides no teaching relative to the fluorinat;on of aromatic isocyanates bearing a haloalkyl s;de chain and no teaching or suggestion of the preparation of aromatic amines. The reference further discloses the treatment of phenylcarbamyl fluoride with water to result ;n the formation of diphenylurea.
British Patent 955,898 (1964) to Farbenfabriken Bayer Aktiengesellschaft discloses the reaction of anhydrous hydrogen fluoride w;th chloromethylphenyl isocyanates to produce the - corresponding fluoromethylphenyl carbamic acid fluoride, or, upon subsequent heating, the corresponding isocyanate. The British patent further discloses the reaction of hydrogen .
fluoride with 2-trichloromethyl-4-chlorophenyl isocyanate in chlorobenzene to prepare 2-trifluoromethyl-4-chlorophenyl carbam;c acid fluor;de. Subsequently, Klauke, Angew. Chem.
Interat. Ed. Vol. 5, No. 9, 848, (1966), in contrast to the teachings of Brit. Pat. 955,898, stated that when o-trichloro-methylphenyl isocyanate undergoes chlor;ne-fluorine exchanye in anhydrous hydrogen fluoride; isomerization occurs simul-~ 3~L3~3 taneously and o-N-(trifluoromethyl)aminobenzoyl fluoride can be isolated, thus implying that o-trifluoromethyl phenyl carbamic acid fluoride is not produced. In U.S. Patent 3,829,460 to Buttner and Klauke assigned to Bayer Aktiengesellschaft, reference is made to the 1966 article and to earlier contradictory teachings and it is disclosed that when hydrogen fluoride is reacted with a trichloromethylphenyl isocyanate wherein the tr;chloromethyl group is in the 2-position to the isocyanate group, it is only possible to obtain the isomers, ;_ 2-N-trifluoromethylamino-benzoyl fluorides.
British Patent 1,164,223 to Klauke et al. teaches the hydrolysis of trifluoromethylphenyl isocyanates with 90-100 percent sulfuric acid to produce the corresponding trifluoro-methyl benzenamine (or amino sulfate) with carbon dioxide as the only byproduct.
The hydrolysis of an NC0 group with acid agents, such as concentrated hydrochloric acid or sulphamic acid is known (Houben-Weyl, Methoden der org. Chemie, 4th Edition, Vol. 11/1, page 953).
Although the utility and commercial value of aromatic amines has been generally recoyni~ed for many years; and, various investigations have been made of reactions of aromatic isocyanates, including aromatic isocyanates, including aromatic isocyanates having a perchlorinated alkyl side chain, there has been no suggestion heretofore that aromatic amines can be prepared by the reaction of hydrogen fluoride with phenyl ~Z 9~ 3~3 carbamic acid fluorides or their precursor phenyl isocyanates.
Furthermore, it has not been known heretofore that 2-(tri-fluoro-methyl)phenyl carbamic fluorides may be conveni~ntly prepared by the isomerization of N-(trifluoromethyl)-anthraniloyi fluorides in the presence of hydrogen fluor;de.
It has now been found that benzenamines, of the formula ~lNH2)q , 10 Rm~ln wherein R is chlorinel fluorine, bromine, phenyl, chlorophenyl, fluorophenyl, or bromophenyl Y is trifluoromethyl or difluoromethyl m is O to 2 ` n is O to 2 , q is 1 to 2 and their hydrofluoride complexes can be prepared by ,.o (A) reacting hydrogen fluoride with a phenyl carbamic fluoride of the formula . ~ NHCOF)q Rm ~ - Xn . . . -, .g~38 where q, m, n, and R are as defined above, and X is trichloromethy~, tribromomethyl, trifluoromethyl, dichloromethyl, dibromomethyl or difluoromethyl with the provision that when X i5 trichloromethyl t tribromomethyl or trifluoromethyl, Y is trifluoromethyl and when X is dichloromethyl, dibromomethyl or d;fluoromethyl, Y is difluoromethyl, to produce a benzenam;ne hydrofluoride complex; of the formula ~ NH2'ZHF)q .. 10 Rm--~Yn where z is about 1 to about 4 and R, Y, q, m and n are as defined above; and, when desired, (B) dissociating the benzenamine~hydrofluoride complex and recovering the benzenamine.
The benzenamine'hydrofluoride resulting from the reaction of hydrogen fluoride with the phenyl carbamic fluoride in accordance with step (A), above, is a complex of variable stoichiometry. The explanation of the variable stoichiometry of these benzenamine'hydrofluoride complexes is not essential to the process of th~s invention or the preparation or use of such complexes. However, it may be postulated that the variable stoichiometry is a result of hydrogen bonding.
The amine'HF complex can be dissociated by heating for example, to temperatures above 100 Celsius. However, at such temperatures the dissociation may be accompanied by undesirable ~ L3~3 reactions such as polymerization. In a preferred manner, the benzenamine'hydrofluoride complex can be readily dissociated by conventional methods such as neutralization with caastic or the like, and the benzenamine recovered from the reaction mixture by conventional physical separation processes such as distillation or the like. The neutralization of amine'hydro-fluorides with KOH, NaOH or the like is disclosed by Berliner et al., Journal of Physical Chemistry, Yol. 32, 1142-1162, (1928).
0 Generally for the reaction of hydrogen fluoride with the phenyl carbamic fluoride, a temperature in the range of about -10 to about 150 Celsius and preferably about 2~ to about 100 Celsius is employed. The reaction may be run neat or in the presence of a carrier medium, such as methylene chloride.
The reaction proceeds smoothly, without the need for a catalyst. However, if desired, a catalyst~ such as a Lewis acid catalyst may be employed.
The reaction of the phenyl carbamic acid fluoride with hydrogen fluoride is carried out in ~he presence of a stoichiometric excess of hydrogen fluoride to result in the formation of the benzenamine'hydrofluoride and carbonyl fluoride as a by-product. The amount of hydrogen fluoride provided to the reaction should be at least slightly in excess of the amount required for the formation of the benzen-amine'hydrofluoride. Preferably the amount of hydrogen fluoride will be sufficient to provide a molar ratio of ~L~ 3 8 hydrogen fluoride:phenyl carbamic fluoride of between 4:1 and 30:1 or greater. It is preferred to carry out the reaction in the liquid phase either in a sealed reactor, that is, an autoclave, Pr at atmospheric pressure, using a cooling condenser~
The phenyl carbamic fluoride reactant may be conveniently prepared by reaction of the corresponding phenyl isocyanate with hydrogen fluoride. The reaction may be carried out in the liquid or vapor phase. In the liquid phase the reaction may be carried out at atmospheric pressure, with the temperature being maintained at below the boiling point of hydrogen fluoride9 or at higher pressures and temperatures under autogenous conditions. It is preferred to carry out the reaction neat.
However, if desired, a carrier medium such as methylene chloride may be employed. ~ypically, ~or a liquid phase reaction, temperatures in the range of about 20 to about 100 Celsius are e~ployed. In a vapor phase reaction the tempera-- ture will generally be above the boiling point of the reaction mixture with no practical upper limit. Typically, the vapor phase reaction is run at a temperature o~ about 250~ to about 350 Celsius. It is preferred to carry out the reaction with at least slight stoichiometric excess of hydrogen fluoride present at all times. Although there is no practical upper limit to the molar ratio of hydrogen fluoride to organic reaction employed, a ratio between absut 5:1 and about 25:1 is generally employed.
~2~ 3~
It has been found that when hydrogen fluoride is reacted with a l-isocyanato-2-(trihalomethyl)benzene to prepare a 2-(trifluoromethyl)phenyl carbamic fluoride, the in si~u formation of N-(trifluoromethyl)-anthraniloyl fluoride occurs S during the reaction. The anthraniloyl fluoride may be isolated and recovered. However, if left under reaction conditions, a rearrangement or isomerization of the N-(trifluoromethyl)phenyl carbamic fluoride is formed. This intermediate formation of an N-(trifluoromethyl)anthraniloyl fluoride and the isomeriza-~ 1~ tion thereof has only been found in reactions involving orthotrihalomethyl-substituted phenyl isocyanates, such as l-isocyanato-2-(trihalomethyl)benzene and ring substituted derivatives, and does not appear to occur in reactions involving meta- or para-trihalomethyl-substituted phenyl isocyanates.
Thus, in accordance with ~he px~s~t invention, it has been found that 2-(trifluoromethyl)phenyl carbamic fluorides of the formula ~F3 Xn ~ NHCOF
~L2 ~3~ 3~
where n is O to 2 and X is independently selected from the group fluoro-, chloro-, bromo-, phenyl-, chlorophenyl-, bromophenyl-, and fluorophenyl- can be prepared by isDmerizing an N-(trifluoromethyl)-anthraniloyl fluoride of the formula ~OF
Xn ~ NHCF3 where n and X are as defined above, in the presence of hydrogen _ fluoride.
The isomerization of N-(trifluoromethyl)-anthraniloyl ~luoride to 2-(trifluoromethyl)phenyl carbamic fluoride proceeds readily in the presence of hydrogen fluoride.
Preferably, the hydrogen fluoride is present in an amount of about 1.5 to about 25 and most preferably about 4.0 to about 20.0 moles of hydrogen fluoride per mole of N-(trifluoro-methyl)-anthraniloyl fluoride. When lesser amounts are employed the isomerization will occur, but the reaction time is ., .
much longer. Greater amounts of hydrogen fluoride may be employed, but provide no special advantage.
It is preferred to carry out the isomerization in the liquid phase. The process may be carried out at atmospheric pressure, with the temperature being maintained at or below the 2~ boiling point of hydrogen fluoride, or at higher pressures and temperatures under autogenous conditions. Temperatures, for ~L~ L3~3 example, in the range of about -lO~ or less to about 150 Celsius or higher may be employed. Preferab~y, temperatures in the range of about 2~ to about lOOD Celsius are employed.
The rea.ction may be run neat or in the presence of a carrier medium such as methylene chloride. The reaction proceeds smoothly without the need for a catalyst. However, if desired, a catalyst, such as a Lewis acid catalyst, such as antimony pentachloride, may be employed.
The reactants susceptible to isomerization in accordance '~ lO with this invention include N-(trifluoromethyl)-anthraniloyl fluoride as well as the various derivatives bearing ring-substituents9 such as, fluoro-, chloro-, bromo-, phenyl-, chlorophenyl-, fluorophenyl-, or bromophenyl-. The isomerization of N-(trifluoromethyl)-anthraniloyl fluoride to 2-(trifluoromethyl)-phenyl carbamic fluoride is of particular interest due to the utility of the latter as an intermediate for the subsequent preparation of 2-(trifluoromethyl)-benzen-amine.
N-(trifluoromethyl)-anthraniloyl fluoride may be 2~ conveniently prepared by the reaction of 1-isocyanato-2-(tri-chlorom~thyl)-benzene. The reaction may be carried out in the liquid or vapor phase. In the liquid phase the reaction may be carried out at atmospheric pressure, with the temperature being maintained at or below the boiling point of hydrogen fluoride, or at higher pressures and temperatures under autogenous conditions. Typically for a liquid phase reaction, ~ 3~
temperatures in the range of about -10 to about 100~ Celsius are employed. In a vapor phase reaction the temperature will ~enerally be above the boiling point of the reaction m~ture with no practical upper limit. Typically, the vapor phase reaction is run at a temperature of about 250 to about 350 Celsius.
It is preferred to carry out the reaction of the 1-isocyanato-2-(trichloromethyl)-benzene and hydrogen fluoride with at least a slight stoichiometric excess of hydrogen f- lo fluoride present at all times. Although there is no theoretical upper limit to the molar ratio of hydrogen fluoride to organic reaction employed, a ratio between about 4:1 and about 2~:1 is generally employed. The reaction may be run neat or in the presence of a carrier medium such as methylene chloride.
The N-(trifluoromethyl)-anthraniloyl fluoride reactant may be employed in substantially pure form or, cGnveniently, as the crude reaction product of hydrogen fluoride and 1-isocyanato-2-(trichloromethyl)-benzene as described in the preceding paragraph. Thus, in one embodiment, the present invention provides a process for the preparation of 2-(trifluoromethyl)-phenyl carbamic fluoride comprising (A) reacting 1-isocyanato-2-(trichloromethyl)-benzene with hydrogen fluoride to form N-(trifluoromethyl)-anthraniloyl fluoride; and (B~ isomerizing the N-(trifluoromethyl)-anthraniloyl fluoride in the presence of hydrogen fluoride to form 2-(trifluoromethyl)phenyl carbamic fluoride.
The 2-(trifluoromethyl)phenyl carbamic fluoride resulting from the isomerization step of this invention may be recovered from the crude reaction product in relatively pure form by convention~l physical separation means, such as distillation.
Alternatively, if the 2-~trifluoromethyl)phenyl carbamic fluoride is to be employed as a chemical intermediate for the preparation of 2-(trifluoromethyl)-benzenamine, or the hydro-fluoride salt thereof, it may be employed in the crude form, without purification or separation from the reaction mixture.
~~ In this instance, the crude 2-(trifluoromethyl)phenyl carbamic fluoride product of the isomerization step is further reacted with hydrogen fluoride to form the hydrofluoride salt or complex of 2-(trifluoromethyl)-benzenamine.
Thus, the phenyl carbamic fluoride reactant may be employed in substantially pure form or as the crude product of the reaction of hydrogen fluoride and a phenyl isocyanate prepared as described above. Thus, in one aspect, this - invention provides a process for the preparation of benzenamine which comprises reacting a phenyl isocyanate with 20 ~ hydrogen fluoride to form a phenyl carbamic acid fluoride and continuing the reaction of the phenyl carbamic acid fluoride with hydrogen fluoride to produce the benzenamine.
In another aspect of the present invention, it has been found surprisingly that the reaction of a phenyl carbamic fluoride with hydrogen fluoride to form the benzamine hydro-fluoride, may be accelerated by the addition of water to the ~ 3~
reaction mixture. The amount of water added to the reaction mixture is not critical and will be effective even in trace amounts. Typically, the amount of water employed will~be in the range ~f about 0.001 to about 2.0 moles of water per mole of phenyl carbamic fluoride. Thus, in a preferred embodiment of this invention, the reaction of hydrogen fluoride with phenyl carbamic fluoride is carried out in the presence of 4 to about 30 moles of hydrogen fluoride per mole of phenyl carbamic fluoride, and in the further presence of about 0.001 to about 2.0 moles of water per mole of phenyl carbamic fluoride to form the corresponding benzenamine hydrofluoride.
The follo~ing specific examples are provided to further illustrate this invention and the manner in which it may be carried out. It will be understood, however, that the specific details given in the examples have been chosen for purpose of illustration and are not to be construed as a limitation on the invention. In the examples, unless otherwise indicated, all parts and percentages are by weight and all temperatures are in degrees Celsius.
Examples 1 6 - Preparation of 2-(Trifluoromethyl)Benzenamine from 2-(Trifluoromethyl)Phenyl Carbamic Fluoride Example_l Three hundred and two parts of 2-(trifluoromethyl)phenyl carbamic fluoride was charged to a polytetrafluoroethylene reaction Yessel and maintained at 0C while 420 parts of liquid ~8~
hydrogen f1uoride was added. The reaction vessel was then sealed and the temperature was increased to about 20~C and maintained thereat, with agitation, for about 16 hours; The reaction vessel was then opened to atmospheric pressure.
Analysis of the organic liquid reaction product by gas chromatographic techniques indicated 54.6% 2-(trifluoromethyl)-phenyl carbamic fluoride starting material.
Example 2 2-(Trifluoromethyl)phenyl carbamic fluoride was prepared in situ by the reaction of 1~7 parts of 1-isocyanato-2-~tri-fluoromethyl)benzene and 336 parts of hydrogen fluoride added over a 15 minute period at 0C. Eighteen p~rts of water was added to the 2-(trifluoromethyl)phenyl carbamic fluoride reaction product and the temperature was increased to about 60DC. The temperature was maintained thereat while hydrogen fluoride was continually refluxed and returned to the reaction mixture. After 24 hours, analysis of the liquid reaction mixture, using gas chromatographic techniques, indicated that . .
the organic reaction product contained 99 percent 2-(tr;fluoro-methyl)benzenamine and 1.0 percent 2-(trifluoromethyl)phenyl carbamic fluoride.
The liquid reaction product is made alkal;ne by addit;on of NaOH and distilled under reduced pressure to recover 2-(tri-fluoromethyl)benzenamine.
Examples 3-6 The procedure of Example 2 was repeated except that conditions were varied as shown, with the results as set forth in Table 1, below.
~Z~ .3 - ~7 ' ...
.~1 E E
C o ~ . ~
~ _ -o ~
~ ~ r~
L~
_ L C
f : .,, E
D c . cr. ~ N
L ~ cr ~ er O~ N
O _ ~ O~ et N
~ al ~c -I
LL
_ ~
~S L~ L
CL ~ u~
., _ r-4 _I
.~
~ O ~ ~ O ~ C~
L .~ r ~ t~ C
~ .~ v~
a, ' E E ' E ~
L
_ a ~ ~ ~ C
1~
e o Cl~ _ ~8g~ 38 Example 7 - Preparation of 2-~rifluoromethyl)Benzenamine 2-(Trifluoromethy1)phenyl carbamic fluoride was prepared in situ by the reaction of 515 parts of 1-isocyanato-2:(tri-chloromethyl)benzene and 1015 parts of hydrogen fluoride added over a per;od of about 2 hours at a temperature of about 0~-4~C. The reaction mixture WdS then sealed in a polytetrafluoroethylene reactor heated to about ~4C and maintained thereat, with agitation, ~or about 48 hours. The reactor was then opened and equipped with a cooling condenser.
! ~0 Thirty-nine parts of water was added and the reaction mixture was stirred at atmospheric pressure for about 48 hours. The reactor was then opened and equipped with a cooling condenser.
Thirty-nine parts of water was added and the reaction mixture was stirred at atmospheric pressure for 120 hours. The reaction mixture was then swept with nitrogen to remove hydrogen fluoride, and rendered alkaline by slow addition of 305 parts of 20~ aqueous sodium hydroxide, washed with methylene chloride, then distilled under reduced pressure to yield 293 parts of 2-(trifluoromethyl)benzenamine.
~0 Example 8 - Preparation of 3-(Trifluoromethyl)Ben2enamine
3-(Trifluoromethyl)phenyl carbamic fluoride was prepared in situ by the reaction of 187 parts of 1--isocyanato-3-(tri-3~3 fluoromethyl)benzene and 370 parts of hydrogen fluoride added over a period of about 15 minutes at about 4C. The reaction mixture was then sealed in a polytetrafluoroe~hylene reaction vessel, heated to about 24C, and maintained therea~, with agitation, for about 96 hours. The reaction vessel ~as then opened to atmospheric pressure and most of the hydrogen fluoride and carbonyl fluoride gases removed. The remaining organic product was analyzed by gas chromatographic techniques, using n-pentadecane as an internal standard, indicating a yield of ~1 parts of 3-(trifluoromethyl)benzenamine.
Example 9 - Preparation of 4-Chloro-2-(Trifluoromethyl)-Benzenamine
Example 9 - Preparation of 4-Chloro-2-(Trifluoromethyl)-Benzenamine
4-Chloro-2 (trifluoromethyl)phenyl carbamic fluoride was prepared in situ by the reaction of 221 parts of 4-chloro-2-(trifluoromethyl)-isocyanatobenzene and 380 parts of hydrogen fluoride added over a period of about 15 minutes at about 4C.
The reaction ~ixture was then sealed in a polytetrafluoro-ethylene reactor, heated to about 24C and maintained at about that temperature, wi~h agitation, for about 96 hours. The reac~or was then opened to atmospheric pressure and most of the hydrogen fluoride and carbonyl fluoride gases removed.
Analysis of the remaining organic product by gas chromato-graphic techniques, using n-pentadecane as an internal standard~ indicated a yield of 55 parts of 4-chloro-2-(tri-2S fluoromethyl)benzenamine.
3~
?O
Example 10 - Preparation of 4-Chloro-3-(Trifluoromethyl)-Benzenamine 4-Chloro-3-(trifluoromethyl)phenyl carbamic fluori~e was prepared in situ by the reaction of 221 parts of 4-chloro-3-(trifluoromethyl)isocyanatobenzene and 450 parts of hydr~gen fluoride added over a period of 15-20 minutes at about 4~C.
The reaction mixture was then sealed in a polytetrafluoro-ethylene reactor, heated to about 24C and maintained thereat, with agitation, for about 96 hours. The reactor was then - 10 opened to atmospheric pressure and most of ~he hydrogen fluoride and earbonyl fluoride gases removed. Analysis of the remaining organic product by gas chromatographic techniques, using n-heptadecane as an internal standard indicated a yield of 77 parts of 4-chloro-3-(trifluoromethyl)benzenamine.
Example 11 ~ Preparation of 4-(Trifluoromethyl)Benzenamine .
4-(Trifluoromethyl)phenyl carbamic fluoride was prepared in situ by the reaction of 224 parts of 1-isocyanato-4-(tri-fluoromethyl)benzene and 460 parts of hydrogen fluoride added over a period of about 35 minutes at about 3C. The reaction mixture was then sealed in a polytetrafluoroethylene reaction vessel, heated to about~24~C, and maintained thereat, with agitation, for about 112 hours. Infra-red analysis of the gaseous phase, when the reaction vessel was opened to atmospheric pressure, indicated large quantities of carbonyl fluoride present. The remaining organic product was analyzed by gas chromatographic techniques, using n-pentadecane as an internal standard, indicating a yield of 114 parts of 4-(tri-fluoromethyl)benzenamine.
~L~ 3E3 Examples 12-16 - Isomeri~ation of N-(Trifluoromethyl)-Anthraniloyl Flu_ride to 2-(Trifluoromethyl) Phenyl Carbamlc Fluoride Example l?
Three parts of N-(trifluoromethyl)-anthraniloyl fluoride was charged to a polytetràfluoroethylene reactor. The reactor was maintained at O~C while three parts of liquid hydrogen fluoride was added. The reactor was then sealed and the temperature was increased to about 25C and maintained thereat, with stirring for about 24 hours. The reactor was opened to atmospheric pressure. Analysis of the liquid reaction product by F-l9 nuclear magnetic resonance techniques indicated 7.7% of the starting anthraniloyl fluoride; 2C.B% of 2-(trifluoro-methyl)benzenamine-hydrofluoride; and 71.5~ of 2-ttrifluoro-methyl)phenyl carbamic fluoride~
Examples 13-16 The procedure of Example 12 was repeated except that various catalysts were incorporated and the molar proportion of hydrogen fluoride and N-(trifluoromethyl) anthraniloyl fluoride reactants was varied with the results as shown in Table 2, below. The analysis of the liquid reaction product, in each instance indicated the major component as 2-(trifluoromethyl)-phenyl carbamic fluoride (Compound I) with minor proportions of 2-(trifluoromethyl)-benzenamine-hydrofluoride (Compound II) and N-(trifluoromethy1)anthran;loyl fluoride starting material.
12~H138 Product CompositiDn~
Mole Ratio Starting Example HF:Organicl ~ L~Material Compound I
13 1~.6 None 1.7 87.0 11.3 14 9.2 SbCl5/5 parts 18.7 78.3 3.4 15 10.3 FS03H/11 parts 16.1 73.6 10.3 16 13.7 HCl 7.4 79.6 13.0 lMole Ratio of HF:N-(trifluoromethyl)-anthraniloyl fluoride HF used was saturated with HCl 32-(tr;fluoromethyl)phenyl carbamic fluoride 42-(trifluoromethyl)benzenamine hydrofluoride ~: ' Examples 17~24 - Preparation of N-(Trifluoromethyl)-Anthraniloyl Fluoride Example 17 Anhydrous hydrogen fluoride and 1-isocyanato-2-(trichloro methyl)-benzene were fed at rates of 24 parts per hour and 3 parts per hour, respectively, (mol ratio of HF: organic reactant = 94.66) into a vapor phase reactor maintained at about 275C. The product gases were cooled, condensed and collected. Analysis, of the reaction product, using~F-19 nuclear magnetic resonance technlques, indicated an es entially 100~ conversion of the organic reactant to N-~trifluoromethyl)-anthran;loyl fluoride.
;
~ 3~3 Examples 18-24 The procedure of Example 12 was repeated except that the temperature of the reactor was varied and the flow rates of reactants were varied to provide molar ratios as shown in the ... .
table below.
Molar Conversions Example Temperature Rat;ol %
18 300 21.29 100 ; 10 19 300 94.60 100 300 48.76 96.1 21 275 35.48 ~6.2 22 275 65.04 lO0 23 250 g4.62 lO0 ~4 250 26.61 97,0 Molar Ratio of HF:1-isocyanato-2-(trichloromethyl)-benzene 2Percent conversion of l-isocyanato-2-(trichloromethyl)-benzene to N-(trifluoromethyl)-anthraniloyl fluoride //
The reaction ~ixture was then sealed in a polytetrafluoro-ethylene reactor, heated to about 24C and maintained at about that temperature, wi~h agitation, for about 96 hours. The reac~or was then opened to atmospheric pressure and most of the hydrogen fluoride and carbonyl fluoride gases removed.
Analysis of the remaining organic product by gas chromato-graphic techniques, using n-pentadecane as an internal standard~ indicated a yield of 55 parts of 4-chloro-2-(tri-2S fluoromethyl)benzenamine.
3~
?O
Example 10 - Preparation of 4-Chloro-3-(Trifluoromethyl)-Benzenamine 4-Chloro-3-(trifluoromethyl)phenyl carbamic fluori~e was prepared in situ by the reaction of 221 parts of 4-chloro-3-(trifluoromethyl)isocyanatobenzene and 450 parts of hydr~gen fluoride added over a period of 15-20 minutes at about 4~C.
The reaction mixture was then sealed in a polytetrafluoro-ethylene reactor, heated to about 24C and maintained thereat, with agitation, for about 96 hours. The reactor was then - 10 opened to atmospheric pressure and most of ~he hydrogen fluoride and earbonyl fluoride gases removed. Analysis of the remaining organic product by gas chromatographic techniques, using n-heptadecane as an internal standard indicated a yield of 77 parts of 4-chloro-3-(trifluoromethyl)benzenamine.
Example 11 ~ Preparation of 4-(Trifluoromethyl)Benzenamine .
4-(Trifluoromethyl)phenyl carbamic fluoride was prepared in situ by the reaction of 224 parts of 1-isocyanato-4-(tri-fluoromethyl)benzene and 460 parts of hydrogen fluoride added over a period of about 35 minutes at about 3C. The reaction mixture was then sealed in a polytetrafluoroethylene reaction vessel, heated to about~24~C, and maintained thereat, with agitation, for about 112 hours. Infra-red analysis of the gaseous phase, when the reaction vessel was opened to atmospheric pressure, indicated large quantities of carbonyl fluoride present. The remaining organic product was analyzed by gas chromatographic techniques, using n-pentadecane as an internal standard, indicating a yield of 114 parts of 4-(tri-fluoromethyl)benzenamine.
~L~ 3E3 Examples 12-16 - Isomeri~ation of N-(Trifluoromethyl)-Anthraniloyl Flu_ride to 2-(Trifluoromethyl) Phenyl Carbamlc Fluoride Example l?
Three parts of N-(trifluoromethyl)-anthraniloyl fluoride was charged to a polytetràfluoroethylene reactor. The reactor was maintained at O~C while three parts of liquid hydrogen fluoride was added. The reactor was then sealed and the temperature was increased to about 25C and maintained thereat, with stirring for about 24 hours. The reactor was opened to atmospheric pressure. Analysis of the liquid reaction product by F-l9 nuclear magnetic resonance techniques indicated 7.7% of the starting anthraniloyl fluoride; 2C.B% of 2-(trifluoro-methyl)benzenamine-hydrofluoride; and 71.5~ of 2-ttrifluoro-methyl)phenyl carbamic fluoride~
Examples 13-16 The procedure of Example 12 was repeated except that various catalysts were incorporated and the molar proportion of hydrogen fluoride and N-(trifluoromethyl) anthraniloyl fluoride reactants was varied with the results as shown in Table 2, below. The analysis of the liquid reaction product, in each instance indicated the major component as 2-(trifluoromethyl)-phenyl carbamic fluoride (Compound I) with minor proportions of 2-(trifluoromethyl)-benzenamine-hydrofluoride (Compound II) and N-(trifluoromethy1)anthran;loyl fluoride starting material.
12~H138 Product CompositiDn~
Mole Ratio Starting Example HF:Organicl ~ L~Material Compound I
13 1~.6 None 1.7 87.0 11.3 14 9.2 SbCl5/5 parts 18.7 78.3 3.4 15 10.3 FS03H/11 parts 16.1 73.6 10.3 16 13.7 HCl 7.4 79.6 13.0 lMole Ratio of HF:N-(trifluoromethyl)-anthraniloyl fluoride HF used was saturated with HCl 32-(tr;fluoromethyl)phenyl carbamic fluoride 42-(trifluoromethyl)benzenamine hydrofluoride ~: ' Examples 17~24 - Preparation of N-(Trifluoromethyl)-Anthraniloyl Fluoride Example 17 Anhydrous hydrogen fluoride and 1-isocyanato-2-(trichloro methyl)-benzene were fed at rates of 24 parts per hour and 3 parts per hour, respectively, (mol ratio of HF: organic reactant = 94.66) into a vapor phase reactor maintained at about 275C. The product gases were cooled, condensed and collected. Analysis, of the reaction product, using~F-19 nuclear magnetic resonance technlques, indicated an es entially 100~ conversion of the organic reactant to N-~trifluoromethyl)-anthran;loyl fluoride.
;
~ 3~3 Examples 18-24 The procedure of Example 12 was repeated except that the temperature of the reactor was varied and the flow rates of reactants were varied to provide molar ratios as shown in the ... .
table below.
Molar Conversions Example Temperature Rat;ol %
18 300 21.29 100 ; 10 19 300 94.60 100 300 48.76 96.1 21 275 35.48 ~6.2 22 275 65.04 lO0 23 250 g4.62 lO0 ~4 250 26.61 97,0 Molar Ratio of HF:1-isocyanato-2-(trichloromethyl)-benzene 2Percent conversion of l-isocyanato-2-(trichloromethyl)-benzene to N-(trifluoromethyl)-anthraniloyl fluoride //
Claims (12)
1. A method for the preparation of a 2-(trifluoro-methyl)phenyl carbamic fluoride of the formula:
wherein m is 0 to 2 and X is independently selected from the group fluorine, chlorine, bromine, phenyl-, chlorophenyl-, fluorophenyl- and bromophenyl-, which comprises isomerizing an N-(trifluoromethyl)anthraniloyl fluoride of the formula:
where m and X are as defined above in the presence of hydrogen fluoride.
wherein m is 0 to 2 and X is independently selected from the group fluorine, chlorine, bromine, phenyl-, chlorophenyl-, fluorophenyl- and bromophenyl-, which comprises isomerizing an N-(trifluoromethyl)anthraniloyl fluoride of the formula:
where m and X are as defined above in the presence of hydrogen fluoride.
2. A method according to claim 1, wherein the iso-merization is carried out at a temperature of about -10° to about 150° Celsius and in the presence of a molar ratio of hydrogen fluoride:N-(trifluoromethyl)anthraniloyl fluoride of greater than about 1.5:1.
3. A method according to claim 1 or 2, wherein m is 0.
4. A method according to claim 1, wherein said iso-merization is carried out at a temperature of about -10°
to about 150°Celsius.
to about 150°Celsius.
5. A method according to claim 1 or 4, wherein the molar ratio of hydrogen fluoride:N-(trifluoromethyl)-anthraniloyl fluoride is about 1.5:1 to about 25:1.
6. A method according to claim 1, which comprises isomerizing N-(trifluoromethyl)-anthraniloyl fluoride, in the presence of hydrogen fluoride to form 2-(trifluoro-methyl)phenyl carbamic fluoride.
7. A method according to claim 6, wherein the molar ratio of hydrogen fluoride:N-(trifluoromethyl)-anthraniloyl fluoride is about 1.5:1 to about 25:1.
8. A method according to claim 7, carried out at about 0° to about 150° Celsius.
9. A method according to claim 8, carried out at autogenous pressure.
10. A method according to claim 6, wherein said N-(tri-fluoromethyl)anthraniloyl fluoride is prepared by reaction of 1-isocyanato-2-(trichloromethyl)-benzene with hydrogen fluoride.
11. A method according to claim 10, for the preparation of 2-(trifluoromethyl)phenyl carbamic fluoride which com-prises:
(A) reacting 1-isocyanato-2-(trichloromethyl)-benzene with excess hydrogen fluoride to form N-(trifluoromethyl)-anthraniloyl fluoride;
(B) isomerizing the N-(trifluoromethyl)-anthraniloyl fluoride in the presence of about 1.5 to about 25.0 moles of hydrogen fluoride per mole of N-(trifluoromethyl)-anthraniloyl fluoride at a temperature of between about -10° and about 150° Celsius to form 2-(tri-fluoromethyl)phenyl carbamic fluoride.
(A) reacting 1-isocyanato-2-(trichloromethyl)-benzene with excess hydrogen fluoride to form N-(trifluoromethyl)-anthraniloyl fluoride;
(B) isomerizing the N-(trifluoromethyl)-anthraniloyl fluoride in the presence of about 1.5 to about 25.0 moles of hydrogen fluoride per mole of N-(trifluoromethyl)-anthraniloyl fluoride at a temperature of between about -10° and about 150° Celsius to form 2-(tri-fluoromethyl)phenyl carbamic fluoride.
12. A method according to claim 10, wherein the N-(trifluoromethyl)-anthraniloyl fluoride is isomerized in the presence of about 4.0 to about 20.0 moles of hydro-gen fluoride per mole of N-(trifluoromethyl)-anthraniloyl fluoride at a temperature of about 20° to about 100°
Celsius.
Celsius.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000549081A CA1248138A (en) | 1983-06-15 | 1987-10-09 | Method for the preparation of 2-(trifluoro- methyl)phenyl carbamic fluoride |
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/504,636 US4466927A (en) | 1983-06-15 | 1983-06-15 | Method for the preparation of 2-(trifluoromethyl)phenyl carbamic fluoride |
| US504,636 | 1983-06-15 | ||
| US06/504,637 US4481370A (en) | 1983-06-15 | 1983-06-15 | Method for the preparation of benzenamines |
| US504,637 | 1983-06-15 | ||
| CA000455705A CA1232286A (en) | 1983-06-15 | 1984-06-01 | Method for the preparation of benzenamines |
| CA000549081A CA1248138A (en) | 1983-06-15 | 1987-10-09 | Method for the preparation of 2-(trifluoro- methyl)phenyl carbamic fluoride |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000455705A Division CA1232286A (en) | 1983-06-15 | 1984-06-01 | Method for the preparation of benzenamines |
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| CA1248138A true CA1248138A (en) | 1989-01-03 |
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| CA000549081A Expired CA1248138A (en) | 1983-06-15 | 1987-10-09 | Method for the preparation of 2-(trifluoro- methyl)phenyl carbamic fluoride |
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1987
- 1987-10-09 CA CA000549081A patent/CA1248138A/en not_active Expired
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