申请人:AMERICAN CYANAMID COMPANY
公开号:EP0234353A1
公开(公告)日:1987-09-02
The present invention relates to
a process for production of α,α,αʹ,αʹ-tetramethyl xylylene diisocyanates which comprises:
(a) reacting a diisopropenyl benzene and isopropenyl-α,α-dimethylbenzyl urethane with an excess of methyl carbamate in the presence of moderate heat and an acid catalyst to convert the olefins to urethanes,
(b) neutralizing said catalyst in the resultant mixture,
(c) stripping unreacted methyl carbamate from the neutralized mixture,
(d) thermally cracking the stripped mixture to convert urethanes to isocyanates whereby a mixture including tetramethyl xylylene diisocyanate and isopropenyl dimethylbenzyl isocyanate is obtained,
(e) recovering methanol from said mixture during thermal cracking.
(f) separating isopropenyl-dimethylbenzyl isocyanate and tetramethyl xylylene diisocyanate from the cracked mixture,
(g) reacting said isopropenyl dimethylbenzyl isocyanate and methanol to form isopropenyl-dimethylbenzyl urethane and,
(h) recycling said isopropenyl-dimethylbenzyl urethane so formed and said stripped methyl carbamate to said reaction with diisopropenyl benzene.
本发明涉及
一种生产α,α,αʹ,αʹ-四甲基二异氰酸酯的工艺,包括
(a) 将二异丙苯和异丙烯基-α,α-二甲基苄基氨基甲酸酯与过量的氨基甲酸甲酯在中等热量和酸催化剂存在下反应,将烯烃转化为氨基甲酸酯、
(b) 在生成的混合物中中和所述催化剂、
(c) 从中和混合物中剥离未反应的氨基甲酸甲酯、
(d) 对汽提混合物进行热裂解,将氨基甲酸乙酯转化为异氰酸酯,得到包括四甲基二异氰酸酯和异丙烯基二甲基苄基异氰酸酯的混合物、
(e) 在热裂解过程中从所述混合物中回收甲醇。
(f) 从裂解混合物中分离异丙烯基二甲基苄基异氰酸酯和四甲基二异氰酸酯、
(g) 使所述异丙烯基二甲基苄基异氰酸酯和甲醇反应生成异丙烯基二甲基苄基氨基甲酸乙酯、
(h) 将形成的异丙烯基二甲基苄基氨基甲酸乙酯和脱除的氨基甲酸甲酯回收,与二异丙烯基苯反应。