CA2126336A1 - Process for producing benzothiazolyl-2-sulphenamides - Google Patents
Process for producing benzothiazolyl-2-sulphenamidesInfo
- Publication number
- CA2126336A1 CA2126336A1 CA 2126336 CA2126336A CA2126336A1 CA 2126336 A1 CA2126336 A1 CA 2126336A1 CA 2126336 CA2126336 CA 2126336 CA 2126336 A CA2126336 A CA 2126336A CA 2126336 A1 CA2126336 A1 CA 2126336A1
- Authority
- CA
- Canada
- Prior art keywords
- disulphide
- dibenzothiazolyl
- mercaptobenzothiazole
- hydrogen peroxide
- amine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
- C07D277/60—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings condensed with carbocyclic rings or ring systems
- C07D277/62—Benzothiazoles
- C07D277/68—Benzothiazoles with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached in position 2
- C07D277/70—Sulfur atoms
- C07D277/76—Sulfur atoms attached to a second hetero atom
- C07D277/80—Sulfur atoms attached to a second hetero atom to a nitrogen atom
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Thiazole And Isothizaole Compounds (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
Process for the preparation of benzothiazolyl-2-sulphen-amides Akzo nv, Arnhem Abstract:
The process for the preparation of benzothia-zolyl-2-sulphenamides, by reacting a 2-mercaptobenzo-thiazole or dibenzothiazolyl 2,2'-disulphide with a primary or secondary aliphatic or cycloaliphatic amine in the presence of hydrogen peroxide as oxidizing agent in an aqueous medium is distinguished in that an aqueous hydrogen peroxide solution is metered at a temperature in the range from 30 to 70°C into an aqueous suspension of the respective amine and the 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide in a ratio in the range between 1.0 and 1.5 mol of amine per mole of 2-mercapto-benzothiazole or per equivalent of dibenzothiazolyl 2,2'-disulphide, preferably in a quantity of below 1.35 mol per mole of 2-mercaptobenzothiazole or per equivalent of dibenzothiazolyl 2,2'-disulphide over a period of at least 60 minutes. The total quantity of water in the reaction mixture should not exceed 1500 g per mole of 2-mercaptobenzothiazole. An environmentally friendly and economic process is provided for the preparation of benzothiazolyl-2-sulphenamides in high yield and with high selectivity.
The process for the preparation of benzothia-zolyl-2-sulphenamides, by reacting a 2-mercaptobenzo-thiazole or dibenzothiazolyl 2,2'-disulphide with a primary or secondary aliphatic or cycloaliphatic amine in the presence of hydrogen peroxide as oxidizing agent in an aqueous medium is distinguished in that an aqueous hydrogen peroxide solution is metered at a temperature in the range from 30 to 70°C into an aqueous suspension of the respective amine and the 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide in a ratio in the range between 1.0 and 1.5 mol of amine per mole of 2-mercapto-benzothiazole or per equivalent of dibenzothiazolyl 2,2'-disulphide, preferably in a quantity of below 1.35 mol per mole of 2-mercaptobenzothiazole or per equivalent of dibenzothiazolyl 2,2'-disulphide over a period of at least 60 minutes. The total quantity of water in the reaction mixture should not exceed 1500 g per mole of 2-mercaptobenzothiazole. An environmentally friendly and economic process is provided for the preparation of benzothiazolyl-2-sulphenamides in high yield and with high selectivity.
Description
2~2633~
Proces~ for the preDaration of benzothiazolyl-2-~ul~hen-~m; des Akzo nv, Arnhem * ~Ir *
De~cription-The present invention relates to a proce3s for the preparation of benzothiazolyl-2-sulphenamides from 2-mercaptobenzothiazoles and primary or secondary amines in the preence of an oxidizing agent.
Sulphenamides are employed in large quantitie~ a~
w lcani2ation accelerator6.
In indu~try, the benzothiazolyl-2-sulphenamides are prepared from the sodium salt of 2-mercaptobenzo-thiazole and the corresponding amine using sodium hypochlorite or chlorine. This reaction takes place in accordance with the following reaction equation (Example:
preparation of ~-cyclohexylben~othiazolyl-2-~ulphen-amide):
~NaOH) MBTNa ~ C6HllNH2 + NaOCl + ~H2SO4 >
MBT-NHC6H1l + NaCl + ~Na2SO~ + H20 (MB~ = 2-mercaptobenzothiazolyl radical) The principal disadvantage in this reaction i~
the formation of large quantities of inorganic salt~, causing heavy pollution of the effluent and rendering impos~ible the recycling of the mo*her liquor and of the wa~h water. Numerous other proce~ses for the preparation of benzothiazolyl-2-sulphenamides have alraady been propo~ed which do not have these disadvantages.
- For example, DE-C 33 25 724 describes a proces~
- in which, in accordance with the general reaction ~ equation ~;:
Proces~ for the preDaration of benzothiazolyl-2-~ul~hen-~m; des Akzo nv, Arnhem * ~Ir *
De~cription-The present invention relates to a proce3s for the preparation of benzothiazolyl-2-sulphenamides from 2-mercaptobenzothiazoles and primary or secondary amines in the preence of an oxidizing agent.
Sulphenamides are employed in large quantitie~ a~
w lcani2ation accelerator6.
In indu~try, the benzothiazolyl-2-sulphenamides are prepared from the sodium salt of 2-mercaptobenzo-thiazole and the corresponding amine using sodium hypochlorite or chlorine. This reaction takes place in accordance with the following reaction equation (Example:
preparation of ~-cyclohexylben~othiazolyl-2-~ulphen-amide):
~NaOH) MBTNa ~ C6HllNH2 + NaOCl + ~H2SO4 >
MBT-NHC6H1l + NaCl + ~Na2SO~ + H20 (MB~ = 2-mercaptobenzothiazolyl radical) The principal disadvantage in this reaction i~
the formation of large quantities of inorganic salt~, causing heavy pollution of the effluent and rendering impos~ible the recycling of the mo*her liquor and of the wa~h water. Numerous other proce~ses for the preparation of benzothiazolyl-2-sulphenamides have alraady been propo~ed which do not have these disadvantages.
- For example, DE-C 33 25 724 describes a proces~
- in which, in accordance with the general reaction ~ equation ~;:
3 3 ~) ; - 2 - AGW2317 (Cu cat.) MBT + HNRR' + ~o2 > MBT-NRR' + H20, ~NH3) a 2-mercaptobenzothiazole or a dibenzothiazolyl 2,2'-disulphide is reacted with a primary or secondary amine, in the presence of molecular oxygen, a copper catalyst and ammonia, at temperatures of from 0 to 100C
in excess amine or a mixture thereof with water as reaction medium. Using this process it ha~ been po~ible to obtain, with high yields and selectivities, a highly pure product in an economic proce3s regime (high space-time yields, recyclability of the mother liquor and continuous procedure). This Patent, to which reference is expressly made hereby, also provides a good overview of the relevant prior art.
In addition, numerous publication~ describe proces~es for the preparation of benzothiazolyl~
2-sulphenamides from -2-mercaptobenzothiazole and corresponding amines using hydrogen peroxide as oxidizing agent, for example DE-A-31 27 193 which i~ cited in DE-C 33 25 724, and also EP-A2-0 180 869, DE-A-30 21 429 and DE-A-27 26 901. These processes u~ing hydrogen peroxide are able to form an advantageous alternative to the abovementioned oxygen process to the extent that -u~like DE-C 33 25 724 - they operate without additional auxiliaries, such as metal cataly~t and ammonia, and at atmospheric pressure. However, these described processes are unsuitable for an industrial application because of the inadequate yields and/or, in some cases, the requirement for very high excesses of amine and hydrogen peroxide. These excesses in turn lead to a reduced selectivity because of secondary reactions, for example to give oxidation products of the amine, sulphites and/or sulphates.
For instance, DE-A-31 27 193 describes a process for the preparation of N-cyclohexylbenzothiazolyl-2-sulphenamide using from 1.5 to 5 mol of cyclohexylamine per mole of 2-mercaptobenzothiazole, where the oxidiæing agents mentioned are ~odium hypochlorite and hydrogen 2~2~3~
_ 3 _ AGW2317 peroxide (Experimental Examples). In all the Experimental Examples using hydrogen peroxide (Examples 9-11), 2-mercaptobenzothiazole is reacted with three times the ~toichiometric quantity of cyclohexylamine and 1.35 times the stoichiometric quantity of hydrogen peroxide; the yield~ indicated are 87.1%, 87.0% and 84.9%. ~owever, a reworking of ~xample 9 led to a yield of only 76%.
In EP-A2-0 180 869, a pxocess is de~cribèd for the preparation of benzothiazolyl-2-sulphenamides from 2-mercaptobenzothiazole or its ~alts and primary amines up to a degree of conversion which is necessarily only 95%, in which process the preferred oxidizing agents are chlorine bleaching liquor, chlorine and hydrogen peroxide, and in which the only BxperLmental Example which relate~ to the use of hydrogen peroxide uses the sodium ~alt of 2-mercaptobenzothiazole a~ starting compound, prescribes the addition of sulphuric acid and sodium hydroxide solution and thus also results in the formation of sodium sulphate as by-product. However, the precondition for an economic, environmentally friendly process is - as already mentioned - that such a pro~es6 should achieve a sufficiently high yield without additional auxiliaries and without by-products which pollute the effluent. Neither in this nor any other respect does EP-A2-0 180 869 provide a concrete indication of this.
The fact that the yield wa~ still inadequate for a problem-free industrial process for the preparation of sulphenamides on the basis of hydrogen peroxide was confirmed only recently in a lecture by Ken M. Dear, "Cleaning Up Oxidation~ with H202~, given at the "International Symposium ORPEC '91", April 29/30 1991, TU
Munich, which can be read in the "Symposium Abstracts".
In thi~ lecture the maximum achievable yields are given as 77% (as against 95% if chlorine-containing oxidizing agents are used), which is in accordance with the yield of only 76% of N-cyclohexylbenzothiazolyl-2-sulphenamide which was obtained in the abovementioned reworking of Example 9 of DE-A-31 27 193. ~his lecture at the same ~ ~ 2 6 t~ 3 1~
in excess amine or a mixture thereof with water as reaction medium. Using this process it ha~ been po~ible to obtain, with high yields and selectivities, a highly pure product in an economic proce3s regime (high space-time yields, recyclability of the mother liquor and continuous procedure). This Patent, to which reference is expressly made hereby, also provides a good overview of the relevant prior art.
In addition, numerous publication~ describe proces~es for the preparation of benzothiazolyl~
2-sulphenamides from -2-mercaptobenzothiazole and corresponding amines using hydrogen peroxide as oxidizing agent, for example DE-A-31 27 193 which i~ cited in DE-C 33 25 724, and also EP-A2-0 180 869, DE-A-30 21 429 and DE-A-27 26 901. These processes u~ing hydrogen peroxide are able to form an advantageous alternative to the abovementioned oxygen process to the extent that -u~like DE-C 33 25 724 - they operate without additional auxiliaries, such as metal cataly~t and ammonia, and at atmospheric pressure. However, these described processes are unsuitable for an industrial application because of the inadequate yields and/or, in some cases, the requirement for very high excesses of amine and hydrogen peroxide. These excesses in turn lead to a reduced selectivity because of secondary reactions, for example to give oxidation products of the amine, sulphites and/or sulphates.
For instance, DE-A-31 27 193 describes a process for the preparation of N-cyclohexylbenzothiazolyl-2-sulphenamide using from 1.5 to 5 mol of cyclohexylamine per mole of 2-mercaptobenzothiazole, where the oxidiæing agents mentioned are ~odium hypochlorite and hydrogen 2~2~3~
_ 3 _ AGW2317 peroxide (Experimental Examples). In all the Experimental Examples using hydrogen peroxide (Examples 9-11), 2-mercaptobenzothiazole is reacted with three times the ~toichiometric quantity of cyclohexylamine and 1.35 times the stoichiometric quantity of hydrogen peroxide; the yield~ indicated are 87.1%, 87.0% and 84.9%. ~owever, a reworking of ~xample 9 led to a yield of only 76%.
In EP-A2-0 180 869, a pxocess is de~cribèd for the preparation of benzothiazolyl-2-sulphenamides from 2-mercaptobenzothiazole or its ~alts and primary amines up to a degree of conversion which is necessarily only 95%, in which process the preferred oxidizing agents are chlorine bleaching liquor, chlorine and hydrogen peroxide, and in which the only BxperLmental Example which relate~ to the use of hydrogen peroxide uses the sodium ~alt of 2-mercaptobenzothiazole a~ starting compound, prescribes the addition of sulphuric acid and sodium hydroxide solution and thus also results in the formation of sodium sulphate as by-product. However, the precondition for an economic, environmentally friendly process is - as already mentioned - that such a pro~es6 should achieve a sufficiently high yield without additional auxiliaries and without by-products which pollute the effluent. Neither in this nor any other respect does EP-A2-0 180 869 provide a concrete indication of this.
The fact that the yield wa~ still inadequate for a problem-free industrial process for the preparation of sulphenamides on the basis of hydrogen peroxide was confirmed only recently in a lecture by Ken M. Dear, "Cleaning Up Oxidation~ with H202~, given at the "International Symposium ORPEC '91", April 29/30 1991, TU
Munich, which can be read in the "Symposium Abstracts".
In thi~ lecture the maximum achievable yields are given as 77% (as against 95% if chlorine-containing oxidizing agents are used), which is in accordance with the yield of only 76% of N-cyclohexylbenzothiazolyl-2-sulphenamide which was obtained in the abovementioned reworking of Example 9 of DE-A-31 27 193. ~his lecture at the same ~ ~ 2 6 t~ 3 1~
- 4 - AGW2317 time documents the current intereYt which is evident in a process based on hydrogen peroxide giving improved yields of sulphenamide.
The object of the present invention wa~ thus to provide an environmentally friendly and economic process for the preparation of benzothiazolyl-2-~ulphenamides in high yield and with high selectivity, starting from 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-di~ulphide, corresponding amines and hydrogen peroxide in accordance with the general reaction eguation MBT + ~NRR' + H202 > MBT-NRR' ~ 2H20.
This object is achieved by a proces~ for the preparation of benzothiazolyl-2-sulphenamides, by reacting a 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide with a primary or secondary aliphatic or cycloaliphatic amine in the presence of hydrogen peroxide as oxidizing agent in an aqueous medium, characterized in that an aqueous hydrogen peroxide solution is metered at a temperature in the range from 30 to 70C into an aqueous suspension of the respective amine and the 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide in a ratio in the range between 1.0 and 1.5 mol of amine per mole of 2-merc:aptobenzothiazole or per equivalent of dibenzothiazolyl 2,2~-diRulphide.
It was very surprising in this context that high yields. are obtained ~ven, and. indeed preci~ely, with a sharply reduced excess of the amine starting compound, connected with the additional advantages of a saving on raw material in comparison with the high quantitie6 required according to DE-A-31 27 193, and an increa~ed selectivity.
~he 2-mercapt^ben~^~h;.- .~ or dibe~ia3 2,2'-disulphide to be reacted as startin~ince ~) according to the invention ma _ ~ple, be the
The object of the present invention wa~ thus to provide an environmentally friendly and economic process for the preparation of benzothiazolyl-2-~ulphenamides in high yield and with high selectivity, starting from 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-di~ulphide, corresponding amines and hydrogen peroxide in accordance with the general reaction eguation MBT + ~NRR' + H202 > MBT-NRR' ~ 2H20.
This object is achieved by a proces~ for the preparation of benzothiazolyl-2-sulphenamides, by reacting a 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide with a primary or secondary aliphatic or cycloaliphatic amine in the presence of hydrogen peroxide as oxidizing agent in an aqueous medium, characterized in that an aqueous hydrogen peroxide solution is metered at a temperature in the range from 30 to 70C into an aqueous suspension of the respective amine and the 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide in a ratio in the range between 1.0 and 1.5 mol of amine per mole of 2-merc:aptobenzothiazole or per equivalent of dibenzothiazolyl 2,2~-diRulphide.
It was very surprising in this context that high yields. are obtained ~ven, and. indeed preci~ely, with a sharply reduced excess of the amine starting compound, connected with the additional advantages of a saving on raw material in comparison with the high quantitie6 required according to DE-A-31 27 193, and an increa~ed selectivity.
~he 2-mercapt^ben~^~h;.- .~ or dibe~ia3 2,2'-disulphide to be reacted as startin~ince ~) according to the invention ma _ ~ple, be the
5~7 compounds mention~!5 724 on page 3, lines 34 / to S~e 3`, lines 64 to page 4, line 4 ~i~y. l~ref~3rably howevor, thc unoubotitutcd P~ q4 1~
~ ~ f~31~.~
- 5a - AGW2317 The 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide to be reacted as the starting substance in accordance with the invention may, for example, be the following compounds:
2-mercapto-4-methylbenzothiazole 2-mercapto-5-methylbenzothiazole :
2-mercapto-6-methylbenzothiazole 2-mercapto-4,5-dimethylbenzothiazole 2-mercapto-4-phenylbenzothiazole 2-mercapto-4-methoxybenzothiazole 2-mercapto-6-methoxybenzothiazole 2-mercapto-5,6-dimethoxybenzothiazole 2-mercapto-6-methoxy-4-nitrobenzothiazole 2-mercapto-6-ethoxybenzothiazole .
2-mercapto-4-chlorobenzothiazole 2-mercapto-5-chlorobenzothiazole ::
2-mercapto-6-chlorobenzothiazole 2-mercapto-7-chlorobenzothiazole 2-mercapto-5-chloro-6-methoxybenzothiazole 2-mercapto-5-chloro-4-nitrobenzothiazole 2-mercapto-5-chloro-6-nitrobenzothiazole :
2-mercapto-4,5-dichlorobenzothiazole 2-mercapto-4,7-dichlorobenzothiazole 2-mercapto-5-nitrobenzothiazole 2-mercapto-6-nitrobenzothiazole 2-mercapto-4-phenylbenzothiazole 2-mercaptonaphthothiazole 2-mercapto-6-hydroxybenzothiazole dibenzothiazolyl 2,2'-disulphide bis(6-methylbenzothiazolyl) 2,2'-disulphide bis(4-methylbenzothiazolyl) 2,2'-disulphide bis(4-methoxybenzothiazolyl) 2,2'-disulphide bis(6 ethoxybenzothiazolyl) 2,2'-disulphide bis(5-chlorobenzothiazolyl) 2,2'-disulphide bis(5-chloro-4-nitrobenzothiazolyl) 2,2'-disulphide bis(3-chloro-5-nitrobenzothiazolyl) 2,2'-disulphide : .
bis(6-nitrobenzothiazolyl) 2,2'-disulphide -REPLAC~NgNT S~EET
212~33~
5b - AGW2317 However, it i~ preferred to employ un~ub~tituted 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide.
;
, :
~:
.,.~.,. . ~
~ ErLU~ hT 8~EEr~
2 ~ 2 6 ~ 3 t~ , 5 ~ V//qS~
-~ - A~;J2 317 ~2,2'-diJ~hld~ mploy~d -Of the amines to be reacted in accordance with the invention, cyclohexylamlne is preferably employed.
According to the invention, both the amine and ¦q~ the hydrogen peroxide can be used even in a very ~light stoichiometric excess over the quantity of 2-mercapto-benzothiazole or dibenzothiazolyl 2,2'-disulphide employed. A larger excess is possible but, from general economic considerations and al~o to guarantee the higher selectivitieE which are ~ought after, the amine excess should be below 50 mol% and the hydrogen peroxide exces~
should be preferably below 35 mol% and particularly preferably below 20 mol%, in each case based on the quantity of 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide employed.
It was in addition highly surprising that the invention can be successfully achieved using a suspension of the reaction mixture, because all of the prior art ~0 cited at the beginning with regard to the preparation of cyclohexylbenzothiazolylsulphenamide refers to the use of the reactants in solution (~ee e.g. DE-A-31 27 193, Patent Claim 1, section (b): "Oxidation of the resulting solution"). Since the production of such solutions is promoted by higher amine e~cesses, as used for example in DE-A-31 27 193, the low excess of amine according to the invention was thu~ expected to lead not only to a reduced product yield but also to a reduced solubility of the reactants in water, and also, to this extent, the proportion of amine according to the invention had not been rendered obvious. In fact, with the ratio of amine to 2-mercaptobenzothiazole according to the invention, u~ing quantities of water which are still economically practicable, it is only a suspension and not a solution which is obtained.
In addition to this, it wa~ al~o surprisingly determined that, in the context of the invention, higher quantities of water actually lead to a drop in the product yield. Therefore a total quantity of water in the ~"~ """"~ 2~,:',`~.,~`'-'""''^`"` ':'.'~':`
2 ~2 ~ 3 1;
~ ~ f~31~.~
- 5a - AGW2317 The 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide to be reacted as the starting substance in accordance with the invention may, for example, be the following compounds:
2-mercapto-4-methylbenzothiazole 2-mercapto-5-methylbenzothiazole :
2-mercapto-6-methylbenzothiazole 2-mercapto-4,5-dimethylbenzothiazole 2-mercapto-4-phenylbenzothiazole 2-mercapto-4-methoxybenzothiazole 2-mercapto-6-methoxybenzothiazole 2-mercapto-5,6-dimethoxybenzothiazole 2-mercapto-6-methoxy-4-nitrobenzothiazole 2-mercapto-6-ethoxybenzothiazole .
2-mercapto-4-chlorobenzothiazole 2-mercapto-5-chlorobenzothiazole ::
2-mercapto-6-chlorobenzothiazole 2-mercapto-7-chlorobenzothiazole 2-mercapto-5-chloro-6-methoxybenzothiazole 2-mercapto-5-chloro-4-nitrobenzothiazole 2-mercapto-5-chloro-6-nitrobenzothiazole :
2-mercapto-4,5-dichlorobenzothiazole 2-mercapto-4,7-dichlorobenzothiazole 2-mercapto-5-nitrobenzothiazole 2-mercapto-6-nitrobenzothiazole 2-mercapto-4-phenylbenzothiazole 2-mercaptonaphthothiazole 2-mercapto-6-hydroxybenzothiazole dibenzothiazolyl 2,2'-disulphide bis(6-methylbenzothiazolyl) 2,2'-disulphide bis(4-methylbenzothiazolyl) 2,2'-disulphide bis(4-methoxybenzothiazolyl) 2,2'-disulphide bis(6 ethoxybenzothiazolyl) 2,2'-disulphide bis(5-chlorobenzothiazolyl) 2,2'-disulphide bis(5-chloro-4-nitrobenzothiazolyl) 2,2'-disulphide bis(3-chloro-5-nitrobenzothiazolyl) 2,2'-disulphide : .
bis(6-nitrobenzothiazolyl) 2,2'-disulphide -REPLAC~NgNT S~EET
212~33~
5b - AGW2317 However, it i~ preferred to employ un~ub~tituted 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide.
;
, :
~:
.,.~.,. . ~
~ ErLU~ hT 8~EEr~
2 ~ 2 6 ~ 3 t~ , 5 ~ V//qS~
-~ - A~;J2 317 ~2,2'-diJ~hld~ mploy~d -Of the amines to be reacted in accordance with the invention, cyclohexylamlne is preferably employed.
According to the invention, both the amine and ¦q~ the hydrogen peroxide can be used even in a very ~light stoichiometric excess over the quantity of 2-mercapto-benzothiazole or dibenzothiazolyl 2,2'-disulphide employed. A larger excess is possible but, from general economic considerations and al~o to guarantee the higher selectivitieE which are ~ought after, the amine excess should be below 50 mol% and the hydrogen peroxide exces~
should be preferably below 35 mol% and particularly preferably below 20 mol%, in each case based on the quantity of 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide employed.
It was in addition highly surprising that the invention can be successfully achieved using a suspension of the reaction mixture, because all of the prior art ~0 cited at the beginning with regard to the preparation of cyclohexylbenzothiazolylsulphenamide refers to the use of the reactants in solution (~ee e.g. DE-A-31 27 193, Patent Claim 1, section (b): "Oxidation of the resulting solution"). Since the production of such solutions is promoted by higher amine e~cesses, as used for example in DE-A-31 27 193, the low excess of amine according to the invention was thu~ expected to lead not only to a reduced product yield but also to a reduced solubility of the reactants in water, and also, to this extent, the proportion of amine according to the invention had not been rendered obvious. In fact, with the ratio of amine to 2-mercaptobenzothiazole according to the invention, u~ing quantities of water which are still economically practicable, it is only a suspension and not a solution which is obtained.
In addition to this, it wa~ al~o surprisingly determined that, in the context of the invention, higher quantities of water actually lead to a drop in the product yield. Therefore a total quantity of water in the ~"~ """"~ 2~,:',`~.,~`'-'""''^`"` ':'.'~':`
2 ~2 ~ 3 1;
- 6 - AGW2317 reaction mixture of 2000 g per mole of 2-mercaptobenzo-thiazole should not be exceeded. The proce~s according to the invention i8 preferably carried out with a total quantity of water of not more than 1500 g and, particularly preferably, not more than 1000 g per mole of 2-mercaptobenzothiazole. Total quantity of water should be understood here as the ~um of the water used for the reaction mixture and the water formed chemically by the reaction.
It is of particular advantage, however, that the process according to the invention can be carried out even with surprisingly low quantities of water and thus that high space/time yields can be achieved. With regard to the quantity of water in the lower range, it iB
apparently only essential for the succe~s of the invention that the solid particles ~uspended in water form a stirrable suspengion.
The concentration of the aqueous hydrogen peroxide solution employed in the process according to the inven~ion can be varied within wide limitæ. They should not be too low, in order not to lower the yields by relatively high quantitieg of water. Relatively highly concentrated hydrogen peroxide golutions lead to a drop in the product selectivity and should also be avoided on 25 safety grounds. Concentrations employed with advantage in the proce~s according to the invention are therefore in the range from 5 to 30% by weight of hydrogen peroxide.
The time within which the aqueous hydrogen peroxide solution is metered into the reaction mixture has an effect in the process according to the invention:
the longer the e chosen metering times, the higher the product yields. Metered addition is preferably carried out within a period of at leagt 60 minutes and, particularly preferably, of at least 150 minutes. In this manner the yields achieved are egsentially greater than 90%, based on 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide employed.
A~ already mentioned, the reaction temperature in the process according to the invention ha~ an effect on 3 ~
It is of particular advantage, however, that the process according to the invention can be carried out even with surprisingly low quantities of water and thus that high space/time yields can be achieved. With regard to the quantity of water in the lower range, it iB
apparently only essential for the succe~s of the invention that the solid particles ~uspended in water form a stirrable suspengion.
The concentration of the aqueous hydrogen peroxide solution employed in the process according to the inven~ion can be varied within wide limitæ. They should not be too low, in order not to lower the yields by relatively high quantitieg of water. Relatively highly concentrated hydrogen peroxide golutions lead to a drop in the product selectivity and should also be avoided on 25 safety grounds. Concentrations employed with advantage in the proce~s according to the invention are therefore in the range from 5 to 30% by weight of hydrogen peroxide.
The time within which the aqueous hydrogen peroxide solution is metered into the reaction mixture has an effect in the process according to the invention:
the longer the e chosen metering times, the higher the product yields. Metered addition is preferably carried out within a period of at leagt 60 minutes and, particularly preferably, of at least 150 minutes. In this manner the yields achieved are egsentially greater than 90%, based on 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide employed.
A~ already mentioned, the reaction temperature in the process according to the invention ha~ an effect on 3 ~
- 7 - AGW2317 the selectivity. It i8 advantageously in the range from 30C to 70C; the best results in accordance with the invention are achieved at reaction temperatures in the range from 40C to 60C. The product yields obtained above 70~ and ~elow 30C are poorer; in the latter case this i8 surprisingly linked with the increa~e formation of by-products (e.g. ~ulphite, ~ulphate and sulphinic and sulphonic acids of 2-mercaptobenzothiazole).
The process according to the invention can be carried out very simply. Auxiliaries such as catalysts or solvents are not required. The addition of water-miscible solvents, such as alcohols, may be advantageous under certain circumstances, for example in order to improve the stirrability of the reaction mixture. ~owever, it is preferred to operate without additional solvents and to choose a quantity of water ~uch that a stirrahle mlxture of the starting compounds is formed, in the form of a fine, homogeneous suspension; for example 2 parts by weight of water per part by weight of 2-mercaptobenzo-thiazole/amine mixture.
In general, the 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide and the amine are mixed with water in a reaction vessel and heated to reaction temperature, for example 50C. However, it is likewise also possible initially to introduce the salt formed from 2-mercaptobenzothiazole and the respective ~mine, especially cyclohexylamine. In this latter case, it is then only necessary to supply the quantity of amine required for the particular stoichiometric excess which 30 i8 desired. The aqueou~ hydrogen peroxide solution is then metered at a uniform rate into the stirred mixture, with the content of the reaction vessel continuing to be maintained at reaction temperature. When metered addition is complete there i6 a relatively short post-reaction phase, for example about 30 minutes, at the same temperature. The reaction mixture i8 then cooled to room temperature and the solid reaction product is filtered off and washed with water, optionally after preliminary wa~hing with a mixture of the particular amine employed
The process according to the invention can be carried out very simply. Auxiliaries such as catalysts or solvents are not required. The addition of water-miscible solvents, such as alcohols, may be advantageous under certain circumstances, for example in order to improve the stirrability of the reaction mixture. ~owever, it is preferred to operate without additional solvents and to choose a quantity of water ~uch that a stirrahle mlxture of the starting compounds is formed, in the form of a fine, homogeneous suspension; for example 2 parts by weight of water per part by weight of 2-mercaptobenzo-thiazole/amine mixture.
In general, the 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide and the amine are mixed with water in a reaction vessel and heated to reaction temperature, for example 50C. However, it is likewise also possible initially to introduce the salt formed from 2-mercaptobenzothiazole and the respective ~mine, especially cyclohexylamine. In this latter case, it is then only necessary to supply the quantity of amine required for the particular stoichiometric excess which 30 i8 desired. The aqueou~ hydrogen peroxide solution is then metered at a uniform rate into the stirred mixture, with the content of the reaction vessel continuing to be maintained at reaction temperature. When metered addition is complete there i6 a relatively short post-reaction phase, for example about 30 minutes, at the same temperature. The reaction mixture i8 then cooled to room temperature and the solid reaction product is filtered off and washed with water, optionally after preliminary wa~hing with a mixture of the particular amine employed
- 8 _ 21 f~ 6 3 3 ~ AGW2317 and water. By di~tillation of the mother liquor, it is possible to recover the amine and also, if de~ired, unreacted 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide.
The purity is determined by titration, HPLC and the melting point.
The product which i8 obtainable by the process according to the invention without additional purification measures is distinguished by a high purity, with values of more than 98%.
The process according to the invention meets essential criteria for an environmentally friendly and economic process for the preparation of N-cyclohexyl-benzothiazolyl-2-sulphenamides: effluent pollution i8 largely avoided, in particular by the absence of ~y-products and auxiliaries, such as catalysts and - in general - solvents too; an environmentally acceptable oxidizing agent is employed; the starting compounds are simple chemicals used in a low stoichiometric excess, in a simple reaction carried out at atmospheric pressure to give a pure end product in yields and selectivities which are high and are superior in comparison to the prior art.
The present invention is illu~trated in more detail by the Experimental ~xamples which follow.
~xample 1 175 g of 95.5% strength 2-mercaptobenzothiazole (1 mol), S00 g of water and 118 g of cyclohexylamine (1.2 mol) were thoroughly mixed in a 1 1 reactor with stirrer, reflux condenser and metering device. The resulting fine suspension of the cyclohexylamine salt of 2-mercaptobenzothiazole was brought to 50C and reacted, with intensive stirring, with a 12.6% strength aqueous hydrogen peroxide solution ~1.1 mol) which was metered in over the course of 5 h. The reaction temperature was maintained at a steady 50C during this procedure.
Stirring was subsequently continued for a further 30 min at the same temperature. The mixture was cooled to room temperature, and the precipitate was filtered off and 2 ~
The purity is determined by titration, HPLC and the melting point.
The product which i8 obtainable by the process according to the invention without additional purification measures is distinguished by a high purity, with values of more than 98%.
The process according to the invention meets essential criteria for an environmentally friendly and economic process for the preparation of N-cyclohexyl-benzothiazolyl-2-sulphenamides: effluent pollution i8 largely avoided, in particular by the absence of ~y-products and auxiliaries, such as catalysts and - in general - solvents too; an environmentally acceptable oxidizing agent is employed; the starting compounds are simple chemicals used in a low stoichiometric excess, in a simple reaction carried out at atmospheric pressure to give a pure end product in yields and selectivities which are high and are superior in comparison to the prior art.
The present invention is illu~trated in more detail by the Experimental ~xamples which follow.
~xample 1 175 g of 95.5% strength 2-mercaptobenzothiazole (1 mol), S00 g of water and 118 g of cyclohexylamine (1.2 mol) were thoroughly mixed in a 1 1 reactor with stirrer, reflux condenser and metering device. The resulting fine suspension of the cyclohexylamine salt of 2-mercaptobenzothiazole was brought to 50C and reacted, with intensive stirring, with a 12.6% strength aqueous hydrogen peroxide solution ~1.1 mol) which was metered in over the course of 5 h. The reaction temperature was maintained at a steady 50C during this procedure.
Stirring was subsequently continued for a further 30 min at the same temperature. The mixture was cooled to room temperature, and the precipitate was filtered off and 2 ~
- 9 - AGW2317 washed with a 10% strength aqueous cyclohexylamine solution and then with water and dried.
In this way 250.2 g were obtained of a product which, in its analytical data (elementary analysi~, IR, lH NMR) is identical with cyclohexylbenzothiazolyl-sulphenamide.
The mother liquor also contained 403 g ofunreacted 2-mercaptobenzothiazole. The degree of conver~ion of 2-mercaptobenzothiazole was thu~ 97.4% and the yield of cyclohexylbenzothiazolylsulphenamide wa~
94.8% of theory.
The purity of the cyclohexylbenzothiazolyl-sulphenamide product i~ 99.1% (titration according to Lichty, J. Applied Chem., 2 (1963), 26), the melting point 100-101C.
E~ample 2 The procedure of Example 1 i~ followed, but the hydrogen peroxide solution is metered in over the course of 3.5 h. Cyclohexylbenzothiazolylsulphen~m;de was obtained in a yield of 92.6% of theory (purity 98.5%).
Example 3 The procedure of Example 1 was followed, but the hydrogen peroxide solution was metered in over the course of 1 h. Cyclohexylbenzothiazolylsulphenamide was obtained in a yield of 89.5% of theory.
Example 4 The procedure of Example 2 was followed, but the reaction temperature was increa~ed to 60C. Cyclohexyl-benzothiazolylsulphenamide was obtained in a yield of 3Q 93.4% of theory (purity 98.2%).
Example 5 In this Example, dibenzothiazolyl 2,2'-disulphide is employed instead of 2-mercaptobenzothiazole.
In the reaction apparatus described in Example 1, 332 g of dibenzothiazolyl 2,2'-disulphide (0.5 mol), 212633~) ` - 10 - AGW2317 1.2 mol of cyclohexylamine and 640 g of water were reacted with intensive stirring and heated to 50C. At this temperature 140 g of aqueous hydrogen peroxide ~olution tO.55 mol) were metersd in over the course of 3.5 h. The product was separated off as in Example 1 and recovered in a yield of 96.7% of theory (purity 98%).
Bxample 6 The procedure of Example 2 was followed, but the 2-mercaptobenzothiazole and cyclohexylamine were initially introduced in 630 g of water, and the hydrogen peroxide was metered in as a 24.6% strength solution (1.1 mol in 152 g of solution).
Cyclohexylbenzothiazolylsulphenamidewasobtained in a yield of 90.4% of theory (m.p. 100-101C).
Example 7 The procedure of Example 1 was followed, but only 1.1 mol of cyclohexylamine were employed.
Cyclohexylbenzothiazolylsulphenamide was recovered in a yield of 92.8% (m.p. 100--101C).
20 Example 8 -The procedure of Bxample 1 was followed, but at a reaction temperature of 40C. Cyclohexylbenzothiazolyl-sulphenamide was obtained in a yield of 92.1% of theory (m.p. 99-101C).
Example 9 The procedure of Example 1 was followed, but at a reaction temperature of 30C. The yield of cyclohexyl-benzothiazolyl~ulphenamide was 87.1% and the degree of conversion of 2-mercaptobenzothiazole was 93.8% of theory (m.p. 99-101C). -~xample 10 This ~xample shows the strong influence of the quantity of water on the yield of product.
2 ~ 633fo The procedure of Example 1 was followed, but the quantity of water for preparing the suspension of mercaptobenzo-thiazole and cyclohexylamine was increased from 500 g to 750 g. The yield of product obtained in thi~ case was only 83~ (m.p. 99-101C). -Bxample 11 (Comparative Example) Example 1 of DE-A-31 27 193 was reworked: in a 250 ml glass reactor, 59.9 g of 50% strength aqueous cyclohexylamine and 0.1 mol of 2-mercaptobenzothiazole were heated to 85C with vigorous ~tirring, with the resulting cyclohexylamine sAlt of 2-mercaptobenzothiazole going largely into solution. After the mixture had been cooled to 45C, 92 g of 5% strength hydrogen peroxide (0.135 mol) were metered in over the course of 60 min with vigorous stirring. Stirring was continued for 30 min at the qame temperature, and then the reaction mixture was cooled to room temperature, and the precipitate was filtered off, washed with 10~ ~trength cyclohexylamine solution and water, and dried. Cyclohexylbenzothiazolyl-sulphenamide was obtained in a yield of 75.6% of theory(melting point 99-100C; purity (Lichty titration) 97.6%).
In this way 250.2 g were obtained of a product which, in its analytical data (elementary analysi~, IR, lH NMR) is identical with cyclohexylbenzothiazolyl-sulphenamide.
The mother liquor also contained 403 g ofunreacted 2-mercaptobenzothiazole. The degree of conver~ion of 2-mercaptobenzothiazole was thu~ 97.4% and the yield of cyclohexylbenzothiazolylsulphenamide wa~
94.8% of theory.
The purity of the cyclohexylbenzothiazolyl-sulphenamide product i~ 99.1% (titration according to Lichty, J. Applied Chem., 2 (1963), 26), the melting point 100-101C.
E~ample 2 The procedure of Example 1 i~ followed, but the hydrogen peroxide solution is metered in over the course of 3.5 h. Cyclohexylbenzothiazolylsulphen~m;de was obtained in a yield of 92.6% of theory (purity 98.5%).
Example 3 The procedure of Example 1 was followed, but the hydrogen peroxide solution was metered in over the course of 1 h. Cyclohexylbenzothiazolylsulphenamide was obtained in a yield of 89.5% of theory.
Example 4 The procedure of Example 2 was followed, but the reaction temperature was increa~ed to 60C. Cyclohexyl-benzothiazolylsulphenamide was obtained in a yield of 3Q 93.4% of theory (purity 98.2%).
Example 5 In this Example, dibenzothiazolyl 2,2'-disulphide is employed instead of 2-mercaptobenzothiazole.
In the reaction apparatus described in Example 1, 332 g of dibenzothiazolyl 2,2'-disulphide (0.5 mol), 212633~) ` - 10 - AGW2317 1.2 mol of cyclohexylamine and 640 g of water were reacted with intensive stirring and heated to 50C. At this temperature 140 g of aqueous hydrogen peroxide ~olution tO.55 mol) were metersd in over the course of 3.5 h. The product was separated off as in Example 1 and recovered in a yield of 96.7% of theory (purity 98%).
Bxample 6 The procedure of Example 2 was followed, but the 2-mercaptobenzothiazole and cyclohexylamine were initially introduced in 630 g of water, and the hydrogen peroxide was metered in as a 24.6% strength solution (1.1 mol in 152 g of solution).
Cyclohexylbenzothiazolylsulphenamidewasobtained in a yield of 90.4% of theory (m.p. 100-101C).
Example 7 The procedure of Example 1 was followed, but only 1.1 mol of cyclohexylamine were employed.
Cyclohexylbenzothiazolylsulphenamide was recovered in a yield of 92.8% (m.p. 100--101C).
20 Example 8 -The procedure of Bxample 1 was followed, but at a reaction temperature of 40C. Cyclohexylbenzothiazolyl-sulphenamide was obtained in a yield of 92.1% of theory (m.p. 99-101C).
Example 9 The procedure of Example 1 was followed, but at a reaction temperature of 30C. The yield of cyclohexyl-benzothiazolyl~ulphenamide was 87.1% and the degree of conversion of 2-mercaptobenzothiazole was 93.8% of theory (m.p. 99-101C). -~xample 10 This ~xample shows the strong influence of the quantity of water on the yield of product.
2 ~ 633fo The procedure of Example 1 was followed, but the quantity of water for preparing the suspension of mercaptobenzo-thiazole and cyclohexylamine was increased from 500 g to 750 g. The yield of product obtained in thi~ case was only 83~ (m.p. 99-101C). -Bxample 11 (Comparative Example) Example 1 of DE-A-31 27 193 was reworked: in a 250 ml glass reactor, 59.9 g of 50% strength aqueous cyclohexylamine and 0.1 mol of 2-mercaptobenzothiazole were heated to 85C with vigorous ~tirring, with the resulting cyclohexylamine sAlt of 2-mercaptobenzothiazole going largely into solution. After the mixture had been cooled to 45C, 92 g of 5% strength hydrogen peroxide (0.135 mol) were metered in over the course of 60 min with vigorous stirring. Stirring was continued for 30 min at the qame temperature, and then the reaction mixture was cooled to room temperature, and the precipitate was filtered off, washed with 10~ ~trength cyclohexylamine solution and water, and dried. Cyclohexylbenzothiazolyl-sulphenamide was obtained in a yield of 75.6% of theory(melting point 99-100C; purity (Lichty titration) 97.6%).
Claims (10)
1. Process for the preparation of benzothiazolyl-2-sulphenamides, by reacting a 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide with a primary or secondary aliphatic or cycloaliphatic amine in the presence of hydrogen peroxide as oxidizing agent in an aqueous medium, characterized in that an aqueous hydrogen peroxide solution is metered at a temperature in the range from 30 to 70°C into an aqueous suspension of the respective amine and the 2-mercaptobenzothiazole or dibenzothiazolyl 2,2'-disulphide in a ratio in the range between 1.0 and 1.5 mol of amine per mole of 2-mercapto-benzothiazole or per equivalent of dibenzothiazolyl 2,2'-disulphide.
2. Process according to Claim 1, characterized in that the total quantity of water in the reaction mixture does not exceed 1500 g per mole of 2-mercaptobenzothia-zole or per equivalent of dibenzothiazolyl 2,2'-disulphide.
3. Process according to Claim 2, characterized in that the total quantity of water in the reaction mixture does not exceed 1000 g per mole of 2-mercaptobenzo-thiazole or per equivalent of dibenzothiazolyl 2,2'-disulphide.
4. Process according to one or more of Claims 1 to 3, characterized in that the hydrogen peroxide is employed in a quantity of below 1.35 mol per mole of 2-mercaptobenzothiazole or per equivalent of dibenzo-thiazolyl 2,2'-disulphide.
5. Process according to Claim 4, characterized in that the hydrogen peroxide is employed in a quantity of less than 1.2 mol per mole of 2-mercaptobenzothiazole or per equivalent of dibenzothiazolyl 2,2'-disulphide.
6. Process according to one or more of Claims 1 to 5, characterized in that the aqueous hydrogen peroxide solution is metered in over a period of at least 60 minutes.
7. Process according to Claim 6, characterized in that the aqueous hydrogen peroxide solution is metered in over a period of at least 150 minutes.
8. Process according to one or more of Claims 1 to 7, characterized in that the reaction is carried out at a temperature in the range from 30°C to 70°C.
9. Process according to Claim 8, characterized in that the reaction is carried out at a temperature in the range from 40°C to 60°C.
10. Process according to one or more of Claims 1 to 9, characterized in that the amine employed is cyclo-hexylamine.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4142693.2 | 1991-12-21 | ||
| DE4142963 | 1991-12-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2126336A1 true CA2126336A1 (en) | 1993-07-08 |
Family
ID=6448128
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2126336 Abandoned CA2126336A1 (en) | 1991-12-21 | 1992-12-16 | Process for producing benzothiazolyl-2-sulphenamides |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0618911A1 (en) |
| CA (1) | CA2126336A1 (en) |
| WO (1) | WO1993013084A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8173762B2 (en) | 2009-07-07 | 2012-05-08 | Bayer Materialscience Ag | Process for the preparation of polycarbonate |
| CN106699685A (en) * | 2016-12-22 | 2017-05-24 | 蔚林新材料科技股份有限公司 | Method for preparing N-cyclohexyl-2-benzothiazole sulfonamide serving as rubber vulcanization accelerator |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SK285660B6 (en) * | 2001-08-10 | 2007-05-03 | Duslo, A. S. | Process of production of N-alkyl-2-benzthiazolylsulfeneimides and method of their purification |
| DE10307138A1 (en) * | 2003-02-20 | 2004-09-02 | Bayer Ag | Process for the preparation of storage-stable benzothiazolylsulfenamides |
| CN100404518C (en) * | 2005-05-31 | 2008-07-23 | 中国石油天然气集团公司 | Method and equipment for preparing 2 - benzothiazole sulphenamide |
| CN110627740A (en) * | 2019-09-30 | 2019-12-31 | 山东尚舜化工有限公司 | Novel environment-friendly production method of accelerator CBS without waste salt and wastewater |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4258197A (en) * | 1979-06-08 | 1981-03-24 | Pennwalt Corporation | Manufacture of sulfenamides |
| DE3440801A1 (en) * | 1984-11-08 | 1986-05-15 | Bayer Ag, 5090 Leverkusen | METHOD FOR PRODUCING STORAGE-STABLE BENZOTHIAZOLE SULFEN AMIDES |
-
1992
- 1992-12-16 CA CA 2126336 patent/CA2126336A1/en not_active Abandoned
- 1992-12-16 WO PCT/EP1992/002917 patent/WO1993013084A1/en not_active Application Discontinuation
- 1992-12-16 EP EP93901029A patent/EP0618911A1/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8173762B2 (en) | 2009-07-07 | 2012-05-08 | Bayer Materialscience Ag | Process for the preparation of polycarbonate |
| CN106699685A (en) * | 2016-12-22 | 2017-05-24 | 蔚林新材料科技股份有限公司 | Method for preparing N-cyclohexyl-2-benzothiazole sulfonamide serving as rubber vulcanization accelerator |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1993013084A1 (en) | 1993-07-08 |
| EP0618911A1 (en) | 1994-10-12 |
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