Patent ID: 7294288

Claim:
A process for preparing a regioregular poly (3-substituted thiophene) having a regioregularity of≧95% head-to-tail (HT) couplings, comprising providing a 3-substituted thiophene having chloro and/or bromo groups in 2-position and 5-position, wherein the substituent in 3-position is an organic group which when it is an unsubstituted and unmodified straight chained or branched alkyl has 5 or more C-atoms, reacting said thiophene with magnesium in a solvent comprising a linear ether or a mixture of linear ethers to form a regiochemical Grignard intermediate or a mixture of regiochemical Grignard intermediates, and polymerizing the Grignard intermediate by adding a suitable catalyst.