1,3-dibromo-2,2-dimethoxypropane

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Properties of substance:

1,3-dibromo-2,2-dimethoxypropane

Group of substances:

organic

Empirical formula (Hill's system for organic substances):

C₅H₁₀Br₂O₂

Structural formula as text:

(BrCH2)2C(OCH3)2

Synthesis 1:

Reference: Gallucci, R. R., & Going, R. Chlorination of aliphatic ketones in methanol / Journal of Organic Chemistry. - 1981. - Vol. 46, No. 12 pp. 2537 [doi: 10.1021/jo00325a019]

CH₃COCH₃ + 2Br₂ + 2CH₃OH → BrCH₂C(OCH₃)₂CH₂Br + 2HBr + H₂O

Bromine (27.6 g) was added dropwise to a solution of acetone (5.0 g) in methanol (100 mL). Initially the reaction was rapidly decolorized but then slowly turned dark red-brown. A sample was worked up 1 h after bromine addition by adding the reaction mixture to an aqueous solution of sodium bisulfite, then extracting with methylene chloride, and washing the organic layer with water. After the solution was dried over anhydrous magnesium sulfate, gas chromatographic analysis showed bromoacetone (38.9%), 1,1-dibromoacetone (13.4%), 1,3-dibromoacetone (28.1%), and both the 1,1-and 1,3-dibromo ketals (4.2% and 9.4%). 1,3-Dibromo products predominated (1,3 vs. 1,1, 68:32).

After being stirred for 24 h the reaction mixture contained almost no free ketone (9.2% 1,1 and 2.6% 1,3). 1,3-Dibromoacetone dimethyl ketal was the major product (64%) with 24% 1,1-dibromo ketal and 15% 1,1,2-tribromoacetone dimethyl ketal. Cooling of the crude reaction mixture to 0 °C resulted in crystallization of the dimethyl ketal of 1,3-dibromoacetone.

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