Abstract: A process for the separation of metaxylene from aromatic C.sub.8 hydrocarbons, particularly from ethylbenzene and paraxylene, wherein a first phase is provided in which the mixture of aromatic hydrocarbons is selectively adsorbed, in vapor phase, into a catalytic bed consisting of zeolite of the Y type, preliminarily exchanged with potassium, and in a second phase a desorption is effected with a suitable solvent. The process, carried out at a temperature of 150.degree. to 200.degree. C. and preferably at atmospherical pressure, permits the recovery of metaxylene, substantially pure and at a concentration much higher than that of the starting mixture.

Abstract: The process for the preparation of 1,4-butynediol through the reaction of acetylene with formaldehyde in the presence of a catalytic metal, preferably copper, is improved by using, as the support of the catalytic metal, a molecular sieve or synthetic zeolite to which the catalytic metal is chemically bonded through an ion exchange reaction.There are obtained increased production rates and selectivity and the polymer of acetylene, namely cuprene, is essentially prevented from being formed.