Abstract: A method of preparing 2,6-di-tert.butylphenol comprises alkylation of phenol with isobutylene at a temperature within the range of from 100.degree. to 110.degree. C in the presence, as a catalyst, of phenyloxyorthotertbutylphenoxyhydroaluminum acid of the formula:[(OC.sub.6 H.sub.5).sub.n (ortho-tert.C.sub.4 H.sub.9 C.sub.6 H.sub.4 O).sub.m Al]Hwhereinn = 1 to 3;m = 1 to 3;n + m = 4.The method of the present invention makes it possible to increase the product yield to 80% by weight and to conduct the process under atmospheric pressure.

Abstract: A method of inhibiting the thermopolymerization of isoprene or butadiene in the process of isolation thereof by extractive distillation from a mixture of hydrocarbons obtained in dehydrogenation of isopentane and butane. The method of inhibiting includes, prior to the introduction of said mixture of hydrocarbons and a polar extractant into an extractive distillation metal apparatus, treating the surface of the apparatus with a 1-25% aqueous solution of passivators, viz. nitrites, sulphites or phosphates of alkali metals at a temperature of 20.degree.-100.degree.C. The mixture of hydrocarbons and the polar extractant with an inhibitor of isoprene or butadiene thermopolymerization introduced into the polar extractant are then fed into said apparatus in an amount of 0.01-1% of the extractant weight. The present method makes it possible to reduce markedly the formation of isoprene and butadiene and, hence, to prevent the plugging of the extractive distillation apparatuses with the aforementioned thermopolymers.

Abstract: A method of producing 2,6-dialkyl- and 2,6-diaralkyl-substituted derivatives of p-cresol of the general formula ##SPC1##Wherein R signifies an alkyl group having from 4 to 12 carbon atoms or ##SPC2##Comprising subjecting phenol to alkylation with olefines having from 4 to 12 carbon atoms or with styrene at a temperature of 50.degree.-150.degree.C in the presence of a catalyst, namely, aluminum, taken in an amount of 0.1-5 wt.% of phenol. 2,6-Dialkyl phenol or 2,6-diaralkyl phenol resulting after from the alkylation is treated with a mixture of formaldehyde and dimethylamine or with a product of their interaction having the formula ##EQU1## at a temperature of 20.degree.-100.degree.C with subsequent catalytic hydrogenolysis of N,N-dimethyl(3,5-dialkyl-4-hydroxybenzyl)/amine or N,N-dimethyl(3,5-diaralkyl-4-hydroxybenzyl/amine at a temperature of 80.degree.-200.degree.C., molar ratio of hydrogen to the product being treated of 1-5:1 and space velocity of 0.1-2 hour.sup..sup.-1.