IE920319A1

IE920319A1 - 2,5-diaryl-1,3,4-oxadiazole hydroxy acids and acetoxy acids,¹process for their synthesis

Info

Publication number: IE920319A1
Application number: IE920319A
Authority: IE
Original assignee: Atochem Elf Sa
Priority date: 1991-01-30
Filing date: 1992-01-30
Publication date: 1992-07-29
Also published as: FI920400A0; CA2060268A1; JPH06107615A; FI920400A; NO920355D0; FR2672050A1; EP0497678A1; NO920355L

Abstract

2,5-Diaryl-1,3,4-oxadiazoles containing hydroxy ester, hydroxy acid and acetoxy acid endings, of formula: in which R1 represents a hydroxyl or acetyl radical and R2 represents a carboxyl radical and where R1 and R2 preferably simultaneously occupy the 3 and 3' or 4 and 4' positions. The hydroxy esters are prepared by cyclisation of the corresponding diaromatic dihydrazide and the hydroxy acids are obtained by saponification of the above hydroxy esters.

Description

i 2,5-DIARIJ>l,3,4-OXADXAZOLB HYDROXY ESTERS, HYDROXY ACIDS AMD ACETOXY ACIDS, PROCESS FOR THEIR SYNTHESIS The present invention provides 2,5-diaryll,3,4«oxadlasole hydroxy esters, hydroxy aolds aad acetoxy acids, oi foznulai ‘wy' in which Ri represents a hydroxy or an acyloxy radical of fornula -OC(«=0)R3 in which R3 represents alkyl having 1 to 4 carbon atone and Rj represents a group of the fornula -COOR4 in which R4 ia hydrogen or alkyl having 1 to 4 carbon atone, where R3 and Ra preferably occupy positions 3 and 3* or 4 and 4' as well ae : the diarcaiatio dlhydrasidarof fornula» WT and salts of the above nentioned compounds.

Rl preferably represents hydroxyl or acetoxy 1$ and r2 preferably represents carboxyl or vethoxyoarbonyl.

The hydroxy esters oan be prepared by cyclisation of the corresponding diarooatio dihydrazide, and the hydroxy adds can be obtained by saponification of the above hydroxy esters. - 2 The hydroxy esters according to the invention can be prepared by cyclisation of the corresponding dihydrazide of formula: to the oxadiazole using SOC12 in the presence of traces 5 of pyridine.

The said dihydrazide may be obtained by condensation of ρ-, o- or m-hydroxybenzohydrazide: with the acid chloride of formula: ^for example according to the procedure of D.L. BRYDON, 10 J. S. FISHER, Polymer, vol 30 page 619 (1989).

The hydroxybenzohydrazide may be obtained in known manner by the reaction of hydrazine hydrate with a hydroxybenzoic acid ester such as methyl hydroxybenzoate.

The acid chloride may be prepared in a ι conventional manner by the reaction of thionyl chloride with a benaecnadljCJurboxyllo acid manoestar at room temperature, it being possible for the monoestar itaelf to be synthesised by monoeaponlflcatlon of the corresponding diester aooording to the procedure of B.W. BOSTS*, Industrial and Engineering Chemistry, Wl. 49, no. 10, page 1€91 (1997).

The hydroxy acids may be prepared by saponification of the previously synthesised hydroxf asters. Acylation of the hydroxy acids «ay be performed, e.g. In an acetic anhydride medium.

The 2,9-dlaryl**l,3,4-oxadiacole hydroxy adds and their acyloxy derivatives aooording to the invention may be used as monomers, in particular-for the synthesis >of thermotropic polymers.

The Bxaaples which follow further illustrate the present invention; Examples 1 to 3 illustrate the preparation of the starting materials.

She meaning of the abbreviations used 30 hereinafter is aa followsι M.p.· Melting point B.p.* Bolling point lit from the literature exp experimental.

EttHEX&JLt ;*4·:»ι<ίί|ίΐIS.QE gd EfiSCHXDBMIfiS A 0.S-1 stirred reactor equipped for reflux is charged with 1 mol (152 g) of methyl p-hydroxybenzoate in 100 cm3 of methanol. 1.5 mol (75 g) of 100% hydrazine hydrate are then run in at room temperature with stirring. When the introduction is complete, the medium is brought to reflux (» 9O’C) for 7 h until the ester has completely disappeared. When the reaction is complete, the mixture is cooled and the solid which is crystallised is filtered off. The product is washed with cold water and dried. 123 g of 99% pure hydrazide are obtained, equivalent to an 81% yield.

Properties of the Product: M.p.° lit : 265eC B.p.’ exp : 258°C - decomposition EXAMPLE 2 - SYNTHESIS OF MONOMETHYL TEREPHTHALATE Procedure: According to B.W. HOTTEN, Industrial and Engineering Chemistry, Vol. 49, no. 10, p. 1691 (1957). 0.75 mol (145.5 g) of dimethyl terephthalate is placed in a 2-1 stirred reactor with 1,125 cm3 of toluene. The suspension is brought to 60°C until the terephthalate has dissolved completely. A methanolic potassium hydroxide solution [0.75 mol (49.4 g) of 85% KOH in 240 cm3 of methanol] is then run in. The introduction takes place in the course of 20 min and the mixture is then brought to reflux for a further hour. When the reaction is complete, the salt formed is filtered off and washed with portions of hot (50°C) toluene to remove the traces of diester. The salt is dried and acidified with 55 cm3 of 12 N HCl. The acid ester obtained is washed with water and dried. 129.5 g of product are obtained, eguivalent to a 95% yield from the diester.

Properties of the Product: -CH, M.p.’ lit : 221eC - 223°C M.p.° exp : 221eC - 223°C EXAMPLE 3 - SYNTHESIS OF THE ACID CHLORIDE OF METHYL TEREPHTHALATE Procedure: 0.2 mol (36 g) of monomethyl terephthalate is placed in a 250-cm3 reactor equipped for reflux, and 45 cm3 of SOC12 are then run in at room temperature. The medium is then brought to reflux until the evolution of S02 and HCl ceases (namely, approximately 4 h). When the reaction is complete, the excess SOC12 is distilled off and the acid chloride (39.5 g, equivalent to a 99% yield) is recovered.

Properties of the Product: —CM, P· ° lit ; 38eC - 40°C P· ’ exp : 53°C - 54°C P· • 135-137°C/12 mm Hg EXAMPLE 4 - SYNTHESIS OF THE DIHYDRAZIDE: 15 (4-hydroxvbenzovl)-2-(4-methoxycarbonvlbenzoyl)hydrazine Procedure According to D.L. BRYDON, J.S. FISHER, Polymer, Vol. 30, p. 619 (1989). 108 g (0.71 mol) of p-hydroxybenzohydrazide suspended in 790 cm3 of dioxane are placed in a 2-1 reactor equipped for reflux with 37.6 g (0.355 mol) of Na2CO3. 141.9 g (0.71 mol) of the abovementioned acid chloride dissolved in 350 cm3 of dioxane are then run in at room temperature. The introduction takes place in the course of 45' and the mixture is then brought to reflux at 70 eC for 9 hours until the acid chloride has disappeared. The medium is cooled to room temperature. The precipitate is filtered off, washed with 4% aqueous HCl solution to remove any remaining hydrazide and then rinsed twice with water. 184 g of a product of purity > 95% (1st crop) are thereby obtained. By concentration of the filtrate, an 87% total yield of pure (99%) product is obtained.

Properties of the Product; M.p.° exp : 238°C - 240°C NMR : in agreement with the structure in and 13C NMR EXAMPLE 5 - SYNTHESIS OF THE HYDROXY ESTER CONTAINING AN OXADIAZOLE UNIT: 2-(4-hydroxyphenyl)-5(4-methoxycarbonvlphenvl)-1,3,4-oxadiazole Procedure: 451.5 g of SOC12 and 9 g of pyridine are placed in a 1-1 reactor equipped for reflux, and 89.8 g (0.286 mol) of dihydrazide are then added portionwise at room temperature. The introduction takes 20 min. The mixture is then brought to reflux at 80°C for 5 h 55 min. The HCl and SO2 which are evolved are trapped and the unreacted SOC12 is distilled off. The solid product is drained and washed with water. 77 g of dry product of purity > 98% in NMR are thereby obtained, equivalent to a 90% yield.

Properties of the product; M.p.° exp ; 243eC - 244eC NMR s in agreement in *Η and 13C NMR Mic roanalys is C H N 0 Σ exp 62.67 4.00 9.25 22.65 98.57 theory 64.79 4.04 9.44 21.50 99.86 EXAMPLE 6 - SYNTHESIS OF THE HYDROXY ACID CONTAINING AN OXADIAZOLE UNIT: 2-(4-hvdroxyphenvl1-5(4-carboxvphenvl)-1,3.4-oxadiazole Procedure: 65 g (0.22 mol) of hydroxy ester suspended in 650 g of 1-propanol are placed in a reactor equipped for reflux. The mixture is brought to reflux and, in the course of 1 h 30 min, an aqueous potassium hydroxide solution (31 g in 100 g of H2O) is run in, refluxing then being maintained for 3 h 20 min.

It is checked by potentiometry that saponification is complete, and 43.5 cm3 of 12 N HCl are then added in the heated state. The product is filtered off and washed. Two crops are obtained, of 53.9 g and .21 g, giving an 80% yield of pure product.

Properties of the Product: M.p.° exp : 305’C - 308’C NMR : in agreement in *H and 13C NMR Microanalvs is C H N 0 Σ exp 63.32 3.62 9.68 23.47 100.09 theory 63.76 3.54 9.91 22.67 99.58 EXAMPLE 7 - SYNTHESIS OF THE ACETOXY ACID CONTAINING AN OXADIAZOLE UNIT; 2-(4-acetoxyphenyl)-5(^-carboxyphenvl)-1,3,4-oxadiazole Procedure: g (0.053 mol) of hydroxy acid in 94 g of acetic anhydride are placed in a reactor equipped for reflux. The mixture is brought to reflux for 30 min (llO’C). It is allowed to cool and the product is precipitated with water. 15.27 g of dry product are thereby obtained, equivalent to an 89% weight yield. Properties of the Product: M.p.°: 276°C - 277°C EXAMPLE 8 - SYNTHESIS OF THE DIHYDRAZIDE: 1-(3 hvdroxvbenzovl)-2-(4-methoxvcarbonvlbenzovl)hydrazine This compound is obtained in a 90% yield according to the procedure of Example 4, by replacing p-hydroxybenzoic acid by m-hydroxybenzoic acid.

M.p.° exp: 226° - 228°C NMR: in agreement with the structure in *H and C NMR.

EXAMPLE 9 - SYNTHESIS OF THE HYDROXY ESTER CONTAINING AN OXADIAZOLE UNIT: 2-(3-hvdroxyphenvl)-5(4-methoxycarbonvlphenyl)-1,3.4-oxadiazole This compound is obtained according to Example in an 84% yield, starting with the dihydrazide of Example 8.

M.p.’ exp : 225’ - 229’C NMR: in agreement with the structure 1H and 13C NMR.

EXAMPLE 10 - SYNTHESIS OF THE HYDROXY ACID CONTAINING AN OXADIAZQLE UNIT: 2-f3-hvdroxyphenvl)-5(4-carboxvphenvl)-1,3.4-oxadiazole This product is obtained according to Example 6 in an 81% yield, starting with the hydroxy ester of 15 Example 9.

COOH M.p.’ exp : 312’ - 316’C NMR: in agreement with the structure in XH and C NMR.

Claims

1. A diaromatic dihydrazide whiah corresponds to the formula» or a salt thereof.

2. 1- (4-Hydroxybenzoyl) -2-(4-methoxycarbonylbenzoyl)-hydrazine.

3. 1-(3 -Hydroxybenzoyl )-2-(4 -me thoxycarbonylbenzoyl)-hydrazine.

4. λ 2,8-diaryl-*l,3,4~oxadlazole hydroxy ester, hydroxy aoid or acetoxy aoid which corresponds to the formula:

in which Κχ represents a hydroxyl or acyloxy radical of formula -O-C(«O)R 3 in whiah R 3 represents alkyl having 1 to 4 carbon atoms and R2 represents a group of ths formula -COOR4 in which R4 is hydrogen or alkyl having 1 to 4 carbon atoms; or a salt thereof.

5. An ester or aoid according to claim 4 in which Μχ represents hydroxyl or acetoxy.

12

6. An ester or acid according to claim 4 or B la which R 2 represents carboxyl or aethoxycatbonyl.

7. An eater or acid according to any one of claims 4 to 6 in whioh Rj and Rj oooupy the positions 3 and 3’ or 4 and 4'·

8. An eater or acid according to claim 4 specifically identified herein.

9. Process for preparing a dlarcmatlo dihydraside aa claimed in olaia 1/ which comprises condensing Ρ-» or - hydrcxybenzoio acid with an add ahlorlde of formula;

10. Process according to olaia 7 substantially aa described in Example * 4 car 8.

11. λ diaromatic dihydrazide aa defined in claim 1 whenever prepared by a process as claimed in olaia 9 or 10.

12. Process for preparing a diaryloxadiasole acid cr eater ee claimed In any one of claims 4 to 8 which compriaee cyolieing e diaromatic dihydrazide ea claimed in any one cf claims l to 3 and 9 using thionyl chloride.

13. Process according to claim 12 which ia carried out in the presence cf pyridine.

14. Process according to claim 12 or 13 substantially as described in Example · s or 7.

- 13 IB. λ diary loxadiasole it old or aster as defined in olala 4 whenever prepared by a prooeee as olaiaed in any one of claisa 12 to 14.

is. Process for preparing a diaxyloxadiasole hydroxy add as olaiaed in any one of olaias 4 to 8 whioh ooaprises saponifying a hydroxy ester aa olaiaed in any one of oleins 4 to 8 and 15.

17. Process aooording to alaia 18 substantially as described In Bxaaple 6 or 10.

18. a diaryloxadiatole hydroxy acid as defined in elaia 4 whenever prepared by a prooeee aa olaiaed in olala 18 or 17.

15. process for preparing a diaryloxadiasole acetoxy aold as olaiaed in any one of olaias 4 to 8 which ooaprises aoetylating a hydroxy aold as olaiaed In any one of olaias 4 to 8 and 18.

ao. Process aooording to olala 19 vhioh is carried out in an acetic anhydride mediua.

21. Process aooording to olala 19 substantially as described in Bxaaple 7.

22. λ diaryloxadiaxole acetoxy aold whenever prepared by a process as olaiaed in any one of olaias 19 to

21.

23. Use of a hydroxy aold or acetoxy add or salt thereof aa olaiaed in any one of olaias 4 to 8, IS, 18 and 22 as a aonoaer in the preparation of a polyaer.