Dichloroacetic Acid → Methacrylic Acid

関与物質

反応手順

To a solution of 2.96 g (3.43 mL, 17 mmol) of 1-methoxy-1-trimethylsiloxy-2-methyl-1-propene and 0.5 mL of tetrabutylammonium biacetate hexahydrate (0.04 M in THF) in 40 mL of THF was added dropwise 35.0 g (39.7 mL, 261 mmol) of trimethylsilyl methacrylate. During the course of the addition the temperature of the reaction mixture rose slowly to 33° C. To increase the rate of polymerization, an additional 0.5 mL of tetrabutylammonium biacetate hexahydrate (0.04 M in THF) was added. After all of the monomer had been added, the temperature slowly rose to 47° C. during 1 hr. When the temperature began to fall, the addition of 19.4 g (19.2 mL, 102 mmol) of 2-phenylethyl methacrylate (purified by passage over a column of basic alumina under argon) was begun. An additional 0.25 mL of tetrabutylammonium biacetate hexahydrate (0.04 M in THF) was added. During the addition the temperature rose from 42° C. to 44° C. When the addition was complete and the temperature began to fall, 0.25 mL of tetrabutylammonium biacetate hexahydrate (0.04 M in THF) was added, and 16.7 g (16.7 mL, 67.8 mmol) of ethoxytriethylene glycol methacrylate (obtained from Polysciences, Inc., Warrington, Pa.; purified by passage over a column of basic alumina under argon) was added dropwise from an addition funnel. Since little temperature change was observed, an additional 0.25 mL of tetrabutylammonium biacetate hexahydrate (0.04 M in THF) was added to insure completion of the polymerization. Analysis of an aliquot of the solution by 1H nmr showed that there was no residual monomer present. To the viscous solution of poly(trimethylsilyl methacrylate [57 mol %]-b-2-phenylethyl methacrylate [26 mol %]-b-ethoxytriethylene glycol methacrylate [17 mol %]) was added 50 mL of THF and 70 mL of a 0.5 volume % solution of dichloroacetic acid in aqueous methanol (prepared from 7.5 mL of dichloroacetic acid, 1030 mL of methanol, and 470 mL of water). The resulting mixture was refluxed for 4 hr and evaporated in a rotary evaporator under reduced pressure. The residual polymer was dried for 48 hr in a vacuum oven at 80° C. to give 46.5 g of poly(methacrylic acid [57 mol %]-b- 2-phenylethyl methacrylate [26 mol %]-b-ethoxytriethylene glycol methacrylate [17 mol %]). 1H NMR analysis of the product showed that no trimethylsilyl ester groups remained.

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