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ChemicalBook CAS DataBase List Cyclopropyl bromide
4333-56-6

Cyclopropyl bromide synthesis

6synthesis methods
Bromocyclopropane has been prepared by the Hunsdiecker reaction by adding silver cyclopropanecarboxylate to bromine in dichlorodifluoromethane at ?29° (53% yield) or in tetrachloroethane at ?20° to ?25° (15–20% yield). Decomposition of the peroxide of cyclopropanecarboxylic acid in the presence of carbon tetrabromide gave bromocyclopropane in 43% yield. An attempt to prepare the bromide via the von Braun reaction was unsuccessful. Ten percent yields are reported for the photobromination of cyclopropane and the photochemical rearrangement of allyl bromide. Treatment of 1,1,3-tribromopropane with methyllithium prepared from methyl bromide furnishes a 60–65% yield of bromocyclopropane.
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Yield:4333-56-6 88%

Reaction Conditions:

with lead(IV) tetraacetate;lithium bromide in tetrachloromethane at 80;Inert atmosphere;Solvent;

Steps:

1-3 [Example 2] Synthesis of cyclopropyl bromide
The first step is to add 250ml carbon tetrachloride in a 500ml four-neck flask under nitrogen protection, then add 21.25g (0.25mol) cyclopropanoic acid and 110.8g (0.25mol) Pb(OAc)4, turn on the stirring, and increase the temperature. At 80°C, add 130.27g (1.5mol) of lithium bromide in batches, keep the reaction for 8h-10h, after the TLC detection reaction is over, filter out the white solid lead bromide, dry it for processing, and then rectify the organic phase under reduced pressure to obtain colorless Liquid cyclopropyl bromide 27.02g, purity 99.6%, yield 88%. In the second step, add 30.8g (0.4mol) of ammonium acetate into a 250ml four-necked flask, add 120ml of ethanol, turn on the stirring, heat to 60°C, and then add 90.7g (0.25mol) of the lead chloride obtained in the first step in batches. ), react for 6h, then add 86.25g (0.5mol) of m-CPBA (0.5mol) in batches and react for 6h, then cool down, filter out the white solid of the product, add the white solid to 200ml anhydrous chloroform, stir for 0.5h, filter, spin-dry the mother liquor The obtained white solid lead tetraacetate can be recycled and used.

References:

Zhonghao (Dalian) Chemical Design Yuan Co., Ltd.;Wang Kewei;Cai Xiaochuan;Zhao Wenwu;Tang Peikun;Han Jianguo CN111099958, 2020, A Location in patent:Paragraph 0013-0018

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