Thiophenedicarboxylic acids

The present method for preparing aromatic dicarboxylic acids has been used to convert phthalic or isophthalic acid to tereph-thalic acid (90-95%) 2,2 -biphenyldicarboxylic acid to 4,4 -biphenyldicarboxylic acid 3,4-pyrroledicarboxylic acid to 2,5-pyr-roledicarboxylic acid and 2,3-pyridinedicarboxylic acid to 2,5-pyridinedicarboxylic acid. A closely related method for preparing aromatic dicarboxylic acids is the thermal disproportionation of the potassium salt of an aromatic monocarboxylic acid to an equimolar mixture of the corresponding aromatic hydrocarbon and the dipotassium salt of an aromatic dicarboxylic acid. The disproportionation method has been used to convert benzoic acid to terephthalic acid (90-95%) pyridine-carboxylic acids to 2,5-pyridinedicarboxylic acid (30-50%) 2-furoic acid to 2,5-furandicarboxylic acid 2-thiophenecar-boxylic acid to 2,5-thiophenedicarboxylic acid and 2-quinoline-carboxylic acid to 2,4-quinolinedicarboxylic acid. One or the other of these two methods is often the best way to make otherwise inaccessible aromatic dicarboxylic acids. The two methods were recently reviewed. ... 

The potassium salt of 2-thiophenecarboxyIic acid is rearranged to the potassium salt of 2,5-thiophenedicarboxylic acid and thiophene in the presence of CdO at 400°C. The free 2,5-thiophenedicarboxylic acid is stable up to 320°C. ... 

It has been shown that 2,3-thiophenedicarboxylic acid is preferentially esterified in the 2-position and the dimethyl ester is preferentially hydrolyzed in this position. The structure proof was difficult to achieve as rearrangements occurred. Thus both isomeric amides (195) and (196) were decarboxylized to the N-methylanilide of 3-thiophenecarboxylic acid (197). The same carbomethoxy benzoyl-thiophene, proved to be 2-carbomethoxy-3-benzoylthiophene (198),... 

In the desulfurization of 3-substituted thiophenes several stereoisomers may be formed in certain cases. Both meso and racemic compounds have been obtained from the desulfurization of 3,4-diaryl-substituted thiophenes. It is claimed, however, that only meso, -diphenyladipic acid is obtained upon desulfurization of 3,4-di-phenyl-2,5-thiophenedicarboxylic acid and only di-isoleucin from 3-thienylglycine. The formation of small amounts of dimeric products in the desulfurization has been discussed with reference to the mechanism of this reaction. ... 

Dibenzothiophenedicarboxylic anhydride and 1,2,3,4-tetrahydro-3,4-dibenzothiophenedicarboxylic acid have been synthesized from 3-vinyIbenzo[6]thiophene (Section IV,B,2). l,4-Dimethyl-2,3-dibenzo-thiophenedicarboxylic acid is formed via oxidation of the trioxide of thiaellipticine (128a) (Section VI,F, 1). 

Studies in the benzene series have been reported by Bock and Rittmeyer365 by carrying out the thermal fragmentations in the gas phase. Finally, few examples of the application of [2 + 2] cycloreversions in the preparation of thioketenes have been reported321. Irradiation in an argon-matrix of 2,3-thiophenedicarboxylic acid anhydride afforded, among other products, thioketene (76) in 20% yield. 

The dimethyl ester of 3,4-dimethyl-2,5-thiophenedicarboxylic acid (377) was converted into 4,6-dicyano-l//,3//-thieno[3,4-c]thiophene (379) via the known intermediate (378) <64JOCl9l9>. Compound (379) was tetrabrominated photochemically, leading to 4,6-dicyano-l,l,3,3-tetrabromo-1 //,3//-thieno[3,4-c]thiophene (380), which lost bromine upon heating in DMF, or with sodium iodide in acetone to give l,3-dibromo-4,6-dicyanothieno[3,4-c]thiophene (164) (94JOC2223) (Scheme 33). 

How would you use a similar approach to synthesize 2,5-thiophenedicarboxylic acid ... 

N. Trukhan, U. Mueller, J. Heimann, and A. Kindler (BASF), Metal-organic framework materials based on 2,5-furandicarboxylic acid or 2,5-thiophenedicarboxylic acid, WO 2011064307, 2011. 

---