Tributylhexadecylphosphonium bromide

A 100-ml., two-necked flask is fitted with a reflux condenser, a gas inlet, and a magnetic stirrer. The flask is charged with 12.0 ml. (15 1 g, 0 1 mole) of 1-bromo-2,2-dimethylpropane (Note 1), aqueous sodium benzenethiolate (0.1 mole) (Note 2), and 1.67 g (0 0033 mole) of tributylhexadecylphosphonium bromide (Notes 3 and 4) This mixture is heated at 70° with vigorous stirring under... 

The tributylhexadecylphosphonium bromide was prepared by heating 0.1 mole of 1-bromohexadecane and 0.1 mole of tributyl-phosphine at 60-70° for three days, according to Starks procedure.2 The product, while hot, was poured into 300 ml. of hexane and the mixture was stirred for 15 minutes. After cooling of the mixture to 0°, a solid product crystallized and was filtered on a Buchner funnel and dried under reduced pressure. It had a melting point of 54-56° (84%). 

Tributylhexadecylphosphonium bromide Phosphonium, tributyl-hexadecyl-, bromide (8,9) (14937-45-2)... 

The first palladium catalyzed reaction reported in an ionic liquid, by Kaufmann in 1996, was a Heck reaction.15 A series of aryl bromides were efficiently coupled with n-butyl acrylate in tributylhexadecylphosphonium bromide ([Ci6PBu3]Br) and tetrabutylammonium bromide ([NBu4]Br) to afford the trans-cinnamates in yields of over 90% in some cases (Scheme 1). Product isolation was achieved by distillation from the ionic liquid or by solvent extraction. 

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