Utilization of Zinc Dust for a Core Monomer 2-Bromo-3-hexylthien-5-ylzinc Bromide: Its Synthesis and Application for the Preparation of Regioregular Poly(3-hexylthiophene)

Table 1

Summary of the study.

Entry	Oxidative addition^a			Polymerization^b
	Solvent	Additive^c	Conversion^d	Solvent	Results
					Yield^e	NMR^f	Mw^g	PDI^g
1	THF	I2	No insertion	—^h
2	DMSO	I2	No insertion	—^h
3	NMP	I2	96% (80 : 20)	NMP	No polymerization
4	DMA	I2	94% (82 :  18)	DMA	50%	>97%	10,000	1.4
5	DMA	I2/LiBr	99% (85 : 15)	DMA	51%	>97%	12,000	1.5
6	DMA	I2/LiBr	98% (85 : 15)	DMA/THF (1 : 1)	62%	>97%	13,000	1.5
7	DMF	I2/LiBr	96% (84 : 16)	DMF	No polymerization
8	DMF	I2/LiBr	96% (84 : 16)	DMF/THF (1 : 1)	40%	>96%	5,000	1.3

aCarried out at refluxing temperature for 24 h, b0.3 mol % Ni(dppe)Cl₂ used, c5.0 mol % I₂/1.0 eq LiBr used, dcalculated by GC, eisolated yield based on monomer, fregioregularity: calculated by the integration of 2-methylene proton in ¹H NMR spectrum, gdetermined by GPC analysis (eluent: THF; calibration: polystyrene standards), and hnot available to perform.