Methyl tert. alkyl ethers prodn. from tert. olefins - and methanol, by liq. phase reaction over a homogeneous acidic catalyst

摘要

Prepn. of ethers (I) comprises liquid phase reaction of a tert. olefin of formula RCH=CR'2 (II) (R = H or alkyl, R' = alkyl) with methanol in the presence of a homogeneous catalyst (III) free from heteropolyacid. (III) has formula HnAaDcOy.xH2O (A is P, B, Si, Ge, Sn, As, Sb, U, Mn, Re, Cu, Ni, Co, Fe, Ce, Th and/or Cr. D is Mo, W and/or V. a = 0.1-10, c = 6-18. n = 1 and is the no. of acidic H atoms in the catalyst. y = 10-70 and x = 0-40). Pref. A is P, Si or Ge, specifically (III) is H4SiMo12O40. - xH2O. Process avoids the corrosion problems associated with strong acid catalysts and minimises the amt. of by-product CH3OCH3 formed. In an example reaction of isobutylene and methanol over the specified catalyst at mole ratio 1:4 gave 81.5% isobutylene conversion and 100% selectivity for methyl tert. butyl ether.