Showing papers on "Methyl vinyl ketone published in 1971"

The Codimerizations of Styrene with Vinyl Compounds Catalyzed by Olefin-palladium(II) Chloride Complexes

Abstract: The codimerization of styrene with vinyl compounds catalyzed by di-μ-chloro-dichlorobis(styrene)dipalladium(II), (Pd(C6H5CH=CH2)Cl2)2, was investigated in a homogeneous system under mild conditions. The reaction of styrene and methyl acrylate carried out at 50°C for 6 hr yielded 220% codimers, 169% dimers of methyl acrylate, and 18% dimers of styrene, on the basis of the palladium(II) used. The codimerizations of styrene with vinyl acetate and with methyl vinyl ketone gave 50% codimer and 125% codimers respectively. When nitroethylene and n-butyl vinyl ether were used as the vinyl compound, no codimers were formed. The codimerization of styrene-d3 with ethylene was also carried out. The reaction mechanism involving the five-coordinate hydridopalladiumolefin intermediate was proposed and discussed in the terms of the distribution of deuterium in the codimer of styrene-d3 and ethylene, the functional group effects of vinyl compounds, and solvent effects on the codimerization.

Imidization reaction in polyvinylamides

Abstract: Depending on their method of preparation, polyvinylamides can have nitrogen contents which vary from the theoretical value to considerably lower values. Cyanamer P-250, a polyacrylamide, manufactured by American Cyanamid Corporation, had a nitrogen content of 17.67% compared to the theoretical value of 19.7%. A polyacrylamide prepared in dioxane at 60°C and initiated by benzoyl peroxide, had a nitrogen content of only 15.5%. These low values are ascribed to loss of ammonia via intramolecular imide formation. We have found that when the intramolecular imidization reaction in poly acrylamide and in polymethacrylamide is driven to completion by heating the polymers in dilute solution, very close to 33% of the amide groups remain unreacted. Thus, unlike poly(methyl vinyl ketone) and poly(vinyl chloride), the poly-vinylamides do not obey Flory's statistical calculation for the random reaction of 1,3 groups in a head-to-tail polymer which predicts isolation of only 13.53% of the vinyl residues. Of the various possible explanations, the hypothesis of larger ring formation seems the most plausible, since specific interactions have been shown to exist between widely spaced amide groups in low molecular weight diamides. The infrared spectra of polyacrylimide and polymethacrylimide are presented and compared with those of the corresponding polyvinylamides. When the nitrogen content of polyacrylamide falls to the 14.9–15.4% N range due to imide formation, the polymer becomes water-insoluble. Because imidization stiffens the polymer chain and introduces weakly acidic groups, the imide content of a polyvinylamide should affect its compatibility with other polymeric systems.

Natural skin coating of the apple and its influence on scald in storage: IV.—Oxidation products of α‐farnesene

Abstract: Among the products of aerial oxidation of a-farnesene are carbonyl compounds of lower molecular weight. Several of these have been analysed, as free compounds or derivatives, with the aid of gas chromatography and mass spectrometry. Some of the identified compounds are known to have no effect on scald but three of them, pyruvaldehyde, methyl vinyl ketone and 6-methyl-5-hepten-2-one, require further study.

Reaction of methyl vinyl ketone with 1-pyrrolidin-1-ylisobutene

Abstract: Methyl vinyl ketone reacts with 1-pyrrolidin-1-ylisobutene to give the tricyclic diketone (2; R = Me). The reaction proceeds through the bisenamine (4; R = Me) formed by self-condensation of the intermediate dienamine (3).

Reactions of Trialkylboranes

Abstract: Diborane reacts with unhindered olefins to form trialkylboranes. In this chapter, several recently discovered carbon–carbon bonds forming reactions of trialkylboranes are presented. Carbon monoxide at atmospheric pressure reacts readily with trialkylboranes at 100–125° to give products that can be oxidized conveniently to trialkylcarbinols. The reaction is sensitive to the presence of water, which inhibits the migration of the third alkyl group and leads to dialkyl ketones. The convenience of the hydroboration reaction combined with the use of carbon monoxide at atmospheric pressure provides the most accessible route to many trialkylcarbinols. Trialkylboranes react rapidly with methyl vinyl ketone to yield methyl ketones of the indicated structure. Only one of the three alkyl groups of borane is converted into product in this process.