Profft, Elmar; John, Peter published the artcile< Studies on thiophene. XII>, Recommanded Product: 4,5-Dichlorothiophene-2-carboxylic acid, the main research area is .
The transformation of 2,3-dichloro-5-(chloromethyl)thiophene (I) to 2,3-dichlorothiophene-5-acetonitrile (II) and 2,3-dichlorothiophene-5-acetic acid (III) was studied. As II was not formed from I + KCN in Me2CO, the reaction was carried out in EtOH-H2O. In 1 hr. 67 g. I was added to a boiling solution of 31 g. KCN in 50 cc. H2O and 20 cc. EtOH, and the mixture boiled for 5 hrs. and cooled, and 200 cc. H2O was added. The aqueous phase was separated and extracted twice with Et2O, which was combined with the oily product, dried over Na2SO4, and distilled at 99-104°/1 mm. Washing with cold petr. ether yielded 10.2 g. II, yellow prisms, m. 45°. Saponification of I was best done by acidic hydrolysis in MeOH. A slow current of dry HCl was led through 10 g. II in 30 cc. MeOH. A solid intermediate was formed. After saturation with HCl, 30 cc. H2O was added, whereupon the mixture was kept 3 days. A yellowish oil separated (III Me ester), b16 124-8°, from which III was obtained with 20% aqueous KOH and purified from NaHCO3 solution to give 1.5 g., m. 106° (petr. ether). Hydrogenation of 5 g. II with 1.3 g. LiAlH4 in 20 cc. Et2O yielded 2,3-dichloro-5-(2-aminoethyl)thiophene. As this compound was unstable, it was isolated as 1.8 g. benzoyl derivative, m. 120°. The high reactivity of I was shown by adding 44 g. I to 5 g. Na and 64 g. CH2(CO2Et)2 in 150 cc. EtOH. The Et ester of bis(2,3-dichlorothienyl)malonic acid (IV) (42 g.), m. 121°, was obtained. Even when smaller amounts of CH2(CO2Et)2 were used, no monosubstituted ester was obtained. Saponification of the Et ester yielded the acid (IV), C13H8Cl4O4S2, m. 171°, which was characterized as the dichloride, m. 137°, diamide m. 285°, di(ethylamide), m. 232° and di(butylamide), m. 221°. At 180° IV decarboxylated, to give 82% β,β’-bis(2,3-dichlorothienyl)isobutyric acid, m. 117°, which was characterized by the amide, m. 144°, butylamide, m. 128°, anilide, m. 199° and 2-naphthylamide, m. 183°. I (2 g.) was kept 6 days with 1.05 g. diethanolamine in 15 cc. Et2O. H2O was added and the acidified solution extracted with Et2O, made alk., and extracted again. The Et2O solution was dried with Na2SO4 and 0.8 g. N-(2,3-dichlorothenyl)diethanolamine-HCl precipitated with dry HCl, m. 138°. From the residue N,O-bis(2,3-dichlorothienyl)diethanolamine-HCl was isolated, m. 163°. In the same way N,N-bis(2,3-dichlorothenyl)ethanolamine-HCl, m. 202°, was obtained from 2 g. I and 1 g. ethanolamine in 15 cc. Et2O; in this reaction no O-substituted compounds could be isolated. 2,3-Dichloro-5-thiophenealdehyde was transformed by a Cannizzaro reaction into the alcohol and 2,3-dichlorothiophenecarboxylic acid (V). V was characterized by its amide, m. 165°, butylamide, m. 83°, ethanolamide, m. 153°, anilide m. 181°, 2-naphthylamide, m. 191° as well as the Me ester, m. 60°.
Journal fuer Praktische Chemie (Leipzig) published new progress about 31166-29-7. 31166-29-7 belongs to class chlorides-buliding-blocks, and the molecular formula is C5H2Cl2O2S, Recommanded Product: 4,5-Dichlorothiophene-2-carboxylic acid.
Referemce:
Chloride – Wikipedia,
Chlorides – an overview | ScienceDirect Topics