摘要:
The invention relates to a new process for the preparation of carboxylic acid chlorides by phosgenation of the corresponding carboxylic acid in the presence of a catalyst.This process is characterized in that the said catalyst is chosen from the compounds represented by the formulae ##STR1## in which R.sub.1 to R.sub.6, which are identical of different, denote: aliphatic, alicyclic, araliphatic or aromatic radicals,or form, in pairs, with the nitrogen atom to which they are attached or with the N-C-N group, a 5- or 6-membered heterocyclic ring.The process applies to most carboxylic acids.The acid chlorides obtained are known and used to produce radical polymerization initiators or pesticides.
摘要:
The invention relates to a process for the preparation of methyl 1,1-dichloromethyl ether or of ethyl 1,1-dichloromethyl ether, according to which methyl formate or ethyl formate is reacted with phosgene, diphosgene, triphosgene or oxalyl chloride or one of their mixtures, at a temperature of between 40.degree. C. and 100.degree. C., in the presence of a catalyst chosen from the group consisting of trisubstituted phosphine oxides and sulphides, trisubstituted phosphine dichlorides, formamides, the products of reaction of formamides with chlorinating agents and mixtures thereof. The 1,1-dichloromethyl ethers are obtained in a high purity. They are useful especially for performing the formylation of aromatic compounds.
摘要:
The subject of the invention is a new process for the preparation of alkyl thiochloroformates.The process according to the invention consists in reacting phosgene with a mercaptan in the presence of a catalyst which is a hexaalkylguanidinium chloride or the corresponding hydrochloride of general formula: ##STR1## in which R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 represent alkyl radicals containing 1 to 4 carbon atoms and in which n may take either the value 0 or the value 1.The preferred catalysts are hexamethylguanidinium chloride and its hydrochloride.The process according to the invention enables very pure alkyl thiochloroformates to be obtained with milder operating conditions and simplified purification operations.
摘要:
The disclosure relates to a process for the synthesis of substituted or unsubstituted aliphatic, cycloaliphatic or araliphatic chloroformates by reaction of the corresponding alcohol with phosgene, diphosgene and/or triphosgene. The reaction is carried out under a pressure of between 15×103 Pa and 85×103 Pa and at a temperature of between −30° C. and +50° C. The process is particularly well suited to the preparation of menthyl chloroformate and benzyl chloroformate.
摘要:
Silica-based substrate surface-modified by grafting covalent links of organic polysubstituted guanidinium groups, and preferably polyakylguanidinium groups. These substrates can be obtained by reacting silica with a polyalkylguanidinium anion, the silanol residual groups of silica being optionally treated with hexamethyldisilazane to stabilize the substrates. These substrates can be used as chlorination and esterification catalysts.