Grignard Reagent Synthesis

The following is a synthesis that involves a Grignard reagent during part of the reaction to yield the final product of  Tris(2-PerFluorohexylethyl)tin hydride:

The Grignard reagent is used in step B of the sythesis to yield Tris(2-perfluorohexyl ethyl)phenyl tin.

This compound is made by frist dissolving Phenyltin trichlorid in dry benzene in a 100-mL, round-bottomed flask under argon at room temperature. The solution is slowly added to a 500-mL, three-necked flask containing the Grignard reagent at room temperature over 1 hour, while stirring.. The reaction mixture is heated at reflux overnight in an oil bath at 50°C, removed from the bath, and allowed to stand at ambient temperature for 4.5 hours, with stirring. The reaction mixture is diluted with ether, vacuum filtered into an Erlenmeyer flask, and hydrolyzed with saturated ammonium chloride solution. Excess magnesium solid is also hydrolyzed with saturated ammonium chloride separately. The mixture is transferred to a separatory funnel. The water layer is removed, and the organic layer is washed three times with 3% sodium thiosulfate. Theorganic layer is dried over magnesium sulfate and filtered under vacuum. The solvent is evaporated to dryness under reduced pressure using a rotovap. The impure product is redissolved in ether and transferred to a 50-mL pear-shaped flask. The ether is removed under reduced pressure. Kugelrohr distillation is peformed to remove a dimer impurity of (C6F13CH2CH2CH2CH2C6F13) at 0.02 mm, 100-120°C for 5 hours. The residue is further purified by column filtration over silica under pressure with hexane. The solvent is evaporated under reduced pressure to leave 17.2 g of pure compound as a colorless oil.

The spectral properties of product of product 1 are as follows: 1H NMR (CDCl3) δ:1.31 [t, 6 H, J = 8.3, 2J(119Sn-H) = 53.4], 2.31 (m, 6 H), 7.41 (s, 5 H) ; 119Sn NMR (CDCl3) − 11.7 ppm; IR (thin film) cm−1: 3100, 2950, 1238, 1190, 1144, 655 ; MS (m/z) 1161 (M+ - Ph), 891 (M+ -CH2CH2C6F13).

The spectral properties of product 3 are as follows: 1H NMR (CDCl3) δ: 1.16 [t, 6 H, J = 8.1, 2J(119Sn-H) = 53.4], 2.35 (m, 6 H), 5.27 (s, 1 H) ; 119Sn NMR (CDCl3) − 84.5 (1J(119Sn-H) = 1835) ;−1: IR (thin film) cm 1842, 1197 ; MS (m/z)1161 (M+ - H), 813 (M+ - CH2CH2C6F13).

Thin layer chromatography was performed using silica plates and eluting with

hexane. Potassium permanganate was used to visualize the spots. The Rf values for products 1 and 3 were 0.38 and 0.37, respectively.