The preparation methods are as follows.
Farks method (diazoacetate method)
Isobutene and trichloroacetaldehyde are condensed into enol under the catalysis of AlCl3, and then subjected to acetylation, zinc powder reduction and acid-catalyzed isomerization to obtain conjugated dienes, namely 1, 1-dichloro-4-methylpentadiene-[1,3], and finally react with methyl diazoacetate (ethyl ester) under the catalysis of copper powder to obtain methyl dichlorochrysanthemum (ethyl ester. 002$S phase mode method
From 2-methylbutene [2] alcohol [1](isopentenol) and methyl acetate (ethyl ester), in the presence of an acidic catalyst such as propionic acid, the condensation Clasen rearrangement is carried out to generate 3, 3-dimethylpentene [4] acid methyl (ethyl) ester [bentine acid methyl (ethyl) ester], the latter and carbon tetrachloride are down-regulated in the presence of benzoyl, 3-dimethyl -4,6,6, 6-tetrachlorohexene [5] acid methyl (ethyl) ester, and then dehydrochlorination in the presence of sodium methoxide, cyclization to form methyl dichlorochrysanthemum acid (ethyl ester).
Phantom-Kulalaifa
From 1,1, 1-trichloro-2-hydroxy-4-methylpentene [4], that is, the enol generated from isobutene and trichloroacetaldehyde in the Farkas method mentioned above, it is catalyzed by p-methylbenzene sulfonic acid Isomerization to obtain 1,1, 1-trichloro-2-hydroxy-4-methylpentene-[3], which is then condensed with trimethyl (ethyl) orthoacetate, 3-Dimethyl -4,6, 6-trichlorohexene [4] acid methyl (ethyl) ester, also produces partial dichlorobutyrolactone during the reaction. 3, 3-dimethyl -4,6, 6-trichlorohexene [4] acid methyl (ethylene) ester is cyclized in the presence of sodium ethoxide to form dichlorochrysanthemum acid methyl (ethylene) ester, and dichlorobutyrolactone can be used in hydrogen chloride or thionyl chloride to open the ring in a (ethylene) alcohol solution to form 3, 3-dimethyl -4,6, 6-trichlorohex, re-cyclizing to obtain methyl (ethyl) dichlorochrysanthemum acid ester.
Vinylidene chloride method
It is similar to the phase mode method, but the raw materials used are different. It avoids the reaction of enol and orthoacetate to form methyl benzoate. The preparation of methyl dichlorochrysanthemum from methyl benzoate is the same as the phase mode method.
Use isoprene as a raw material to react with two molecules of hydrogen chloride to generate 1, 3-dichloro-3-methylbutane, and then react with vinylidene chloride to generate 1,1, 5-trichloro-3, 3-dimethylpentene [1], and then hydrolyze with concentrated H2SO4 or alkali to obtain 5-chloro-3, 3-dimethylpentanoic acid, which is esterified with methanol in acidic medium to generate the corresponding 5, methyl 3-dimethylpentanoate, and then dehydrochlorinated with sodium methoxide to obtain methyl 3, 3-dimethylpentene [4] acid, that is, methyl bentine acid.
Cyclobutanone method
Acrylonitrile and carbon tetrachloride under pressure, using Cu as a catalyst, carry out a telomerization reaction to generate 2,4,4,4, 4-tetrachlorobutyronitrile, further hydrolysis, acylation to generate 2,4,4, 4-tetrachlorobutyryl chloride, and then in the presence of triethylamine, pressure dehydrochlorination to generate enone, and then react with isobutylene under pressure to generate 2-chloro-2-tr, 3-Dimethylcyclobutanone, in the presence of triethylamine, is rearranged by Cine to obtain 2-trichloroethyl -3, 3-dimethyl-4-chlorocyclobutanone, and then rearranged by Favorski to obtain 3-trichloroethyl -2, 2-dimethylcyclopropane carboxylic acid, and then treated with alkali to dehydrochlorination to obtain dichlorochrysanthemum acid.
NRDC method
The Wittig reaction of methyl caronate and triphenylmethylene phosphine dichloride was carried out to obtain methyl dichlorochrysanthemum.