摘要
全氟异丁烯是热解法生产四氟乙烯与六氟丙烯的剧毒副产物,通常焚烧销毁。其综合利用途径是用甲醇处理得到八氟异丁基甲基醚,八氟异丁基甲基醚可以转化为六氟丙酮、１,１,１,３,３,３－六氟丙烷、１,１,１,３,３－五氟丙烯、九氟异丁基甲基醚、α－(三氟甲基)芳基乙酸等有用含氟产品。
The present paper introduces and reviews the property and comprehensive utilization of perfluo-roisobutylene (PFIB). PFIB (( CF3)2C=CF2 ) is a by-product in the manufacture of tetrafluoroethylene and hexafluoropropylene by pyrolysis of chlorodifluoromethane and tetrafluoroethylene. It is a kind of highly toxic, colorless gas and is usually burned as waste product. Because of the drainage of π-electrons by fluorine atoms,the electron density at the double bond decreases. As a consequence, PFIB is a good electrophile and nucleophilic additions occur readily with a variety of nucleophiles available such as alcohols, ammonia, second amines,etc. The addition reactions are usually accompanied by second reactions, mainly elimination of hydrogen fluoride. Among those reactions, the addition of methanol is of great importance. Since the reaction is carried out in a very simple way and the yield is generally very good, methanol is widely used to remove PFIB to form PFIB-methanol adduct. In practice, PFIB-methanol adduct is a mixture of adduct (2H-octafluoroisobutyl methyl ether) and addition-elimination product (hep-tafluoroisobutenyl methyl ether), and the toxicity is relatively lower compared with PFIB. But usually PFIB-methanol adduct is destroyed as waste product too. Because gaseous PFIB is too dangerous to deal with, almost all research work that has been done to make the comprehensive utilization of PFIB begins with PFIB-methanol adduct. PFIB-methanol adduct can be converted to useful and commercially valuable fluorine-containing products. Hexafluoroacetone or its hydrate is produced by oxidizing heptafluo-roisobutenyl methyl ether with permanganate or ozone. 1,1,1,3 , 3 , 3-hexafluoropropane and 1,1,1,3,3-pentafluoropropylene are formed by reacting PFIB-methanol adduct with water and trialkyl amine or water alone. Nonafluoroisobutyl methyl ether is prepared by fluorinating PFIB-methanol adduct with fluorine. α,α-bis (trifluoromethyl) arylacetic acid ester is obtained by treating heptafluoroisobutenyl methyl ether with ozone and aromatic compounds, α,α-bis(trifluoromethyl) arylacetic acid ester can be converted to the corresponding carboxylic acid salt under the action of the base and water, followed by decarboxylation to form an olefinic compound, and further by hydrolysis to form α-(trifluoromethyl) arylacetic acid. These are reviewed in the present paper.
出处
《安全与环境学报》
CAS
CSCD
2001年第1期37-40,共4页
Journal of Safety and Environment
