Amberlyst ether formations

Formation of Acetals and Ketals. The protection of carbonyl groups as acetals or ketals is a necessary requirement for the manipulation of many multifunctional molecules. Amberlyst 15 and Dowex 50 are excellent acidic catalysts for such transformations. When trlethyl orthoformate (eq 1) is used, enol ether formation from a,/3-unsaturated carbonyls can also occur. 

The absorption of isobutene in subazeotropic aqueous ethanol, to give ETBE and tert-butyl alcohol (TBA) was investigated [58]. The experiments were conducted in a stainless steel autoclave of one liter capacity. The catalyst used was Amberlyst-15, which is an acidic, macroporous cation exchange resin, in the form of spherical beads. In the ETBE synthesis reaction using ethanol and isobutene, the side reactions are the dimerization of isobutene to form diisobutene and the formation of diethyl ether. These byproducts show a tendency to increase with an increase in reaction temperature. Hence, the... 

A mixture of cis- and truns-1-methoxycyclododecenes was prepared in 98% yield from cyclododecanone by a modification of Claison s method of ketal formation. Amberlyst-15 is a superior catalyst for the preparation of enol ethers and acetals. 

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