Abstract: Toluene is virtually impossible to separate from similar boiling non-aromatic hydrocarbons by conventional rectification or distillation. Toluene can be readily separated from similar boiling non-aromatic hydrocarbons by using extractive distillation in which the extractive agent is a mixture of phthalic anhydride and/or maleic anhydride plus a suitable solvent. A typical mixture comprises phthalic anhydride, maleic anhydride and glycerol triacetate.

Abstract: Ethylbenzene and para-xylene and/or meta-xylene are difficult to separate by distillation because they boil only 2.3 C..degree. and 3.1 C..degree. apart. Ethylbenzene can be readily separated from the xylenes by using extractive distillation in which the extractive distillation agent is a mixture of pentachlorophenol admixed with certain chlorinated and/or oxygenated organic compounds boiling higher than the xylenes. A typical mixture comprises pentachlorophenol, benzene hexachloride and 1,2,4-trichlorobenzene.

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds and a new polymerization inhibitor therefor. The process comprises subjecting a vinyl aromatic compound to elevated temperatures in a distillation system in the presence of a new polymerization inhibitor comprising 2,6-dinitro-p-cresol. Also disclosed is a distillation method and apparatus for use with this inhibitor.

Abstract: The separation of butadiene-1,3 from other C-4 hydrocarbons of lesser degree of unsaturation by extractive distillation with alkoxynitrile or aqueous alkoxynitrile as selective solvent is carried out with improved selectivity, without appreciable formation of butadiene-1,3 polymer and with consequent savings in energy by adding to the alkoxynitrile or aqueous alkoxynitrile an organic cosolvent which is dimethyl sulfoxide, sulfolane, butyrolactone, N-methyl pyrrolidone, morpholine, or trimethyl phosphate and/or an inhibitor which is 2,4-dinitrophenol or 2,4-dinitro-ortho-cresol. The organic cosolvent is present in the selective solvent composition in an amount of 5 to 30 percent by weight and the inhibitor in an amount of 0.05 to 0.6 percent by weight.

Abstract: Formation of butadiene-1,3 polymer during the extractive distillation of a C-4 hydrocarbon mixture to separate and purify butadiene-1,3 using a solvent composition in which an alkoxynitrile is present in a proportion of 50-99 percent by weight, is decreased through inclusion in the solvent of a synergistic combination of 2,4-dinitrophenol and phosphoric acid, each in a proportion of 0.05 to 0.5 percent by weight.

Abstract: The removal of the polymerization inhibitor p benzoquinone from acrylic and methacrylic monomers is effectuated by adding to the inhibited monomers either prior to distillation or during distillation in a distillation zone, sufficient amounts of a monoalkyl substituted hydroquinone, a 2,5-dialkyl substituted hydroquinone or a dihydroxynaphthalene to prevent the benzoquinone from co-distilling with the monomer or to convert the benzoquinone in a distillation zone to a non-volatile compound during the distillation so that the converted benzoquinone returns to the feed flask.

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds which comprises subjecting such compounds to distillation conditions in the presence of an effective amount of a halo-6-nitro-p-cresol as a polymerization inhibitor.

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds and a new polymerization inhibitor therefor. The process comprises subjecting a vinyl aromatic compound to elevated temperatures in a distillation system in the presence of a new polymerization inhibitor comprising 2,6-dinitro-p-cresol.

Abstract: The invention relates to an improved process for removing water, under elevated temperature, from aqueous gel of water soluble polymer, such as polymer or copolymer of acrylamide and/or quaternary ammonium salts of dialkylaminoamlkylmethacrylate, to prevent from the deterioration of polymer properties. The process is accomplished by addition of polyhydric phenols, benzoquinones or derivatives thereof prior to removal of water.

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds and a new polymerization inhibitor therefor. The process comprises subjecting a vinyl aromatic compound to elevated temperatures in a distillation system in the presence of a new polymerization inhibitor comprising m-nitro-p-cresol.

Abstract: The present invention provides a process for purifying an organic isocyanate which comprises heating an organic isocyanate in admixture with a treating agent selected from the group consisting of a metal salt of mercaptobenzothiazol, a dithiocarbamic acid derivative, an alkyl-substituted phenol, a thio-bisphenol, and a triaryl phosphite at a temperature not lower than 100.degree. C and subsequently distilling the thusly treated mixture to recover a purified organic isocyanate.

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds which comprises subjecting such compounds to distillation conditions in the presence of an effective amount of a combination of phenothiazine and a phenolic compound, preferably tert-butylcatechol (TBC), as a polymerization inhibitor system in the presence of oxygen.

Abstract: In a process of extractive distillation, the combination of operating with two liquid phases in at least the uppermost trays of the column, preferably while maintaining the column operation at substantially an optimum reflux ratio, results in increased efficiencies and minimum requirements for selective solvent.

Abstract: A process for separating mixtures of close boiling alkenes and alkanes which employs catalytic dealkylation of alkylphenols.

Abstract: Styrene is inhibited against polymerization during the distillation thereof by incorporating therein, in an amount sufficient to inhibit polymerization thereof, the dinitrophenol solution recovered from styrene still residues or tars resulting from the distillation of styrene in the presence of dinitrophenol. The recovered dinitrophenol solution is a more effective polymerization inhibitor than dinitrophenol per se.

Abstract: A process for separating mixtures of close boiling, high-molecular weight alkenes and alkanes which employs phenoxide-catalyzed alkyl displacement.

Abstract: The present invention relates to the use of quinone alkides as polymerization inhibitors in a styrene purification process. The inhibitors are prepared by oxidizing hindered phenols to the corresponding quinone alkide.

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds and a new polymerization inhibitor therefor. The process comprises subjecting a vinyl aromatic compound to distillation conditions in a distillation system and adding to the system the new polymerization inhibitor comprising a mixture of N-nitroso diphenyl amine and a dinitro-O-cresol.