[C:1]1([C:7]2[S:8][CH:9]=[CH:10][CH:11]=2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.C([Li])CCC.[C:17](=[O:19])=[O:18].CCOCC>O1CCCC1.CCCCCC>[C:1]1([C:7]2[S:8][C:9]([C:17]([OH:19])=[O:18])=[CH:10][CH:11]=2)[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1
A solution of 2-phenylthiophene (16.0 g, 0.1 mole) in 100 ml anhydrous tetrahydrofuran (THF) is treated dropwise with a solution of n-butyl lithium (0.11 mole) in hexane (2 M solution). Thereafter the mixture is stirred for 1 hr. The resulting black solution is poured onto 50 g of solid CO2 covered with ether. When all the CO2 is evaporated, the mixture is treated with 200 ml of water, acidified with 10% HCl and extracted with ether. The extract is washed with 5% NaOH. The latter washings are cooled and rendered acidic with 20% HCl. The resulting precipitate is collected and recrystallized from 100 ml CCl4 to give 5-phenyl 2-thiophenecarboxylic acid, mp 180° C, γmaxCHCl 3 1665 cm-1, as yellow green crystals.
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