Coordination polymerization of ω-alkenoates and ω-epoxyalkanoates

As functional polymers have become more and more used, the need for a general synthesis of addition polymers with functional groups became greatly important. We have achieved the polymerization of ω-alkenoates with coordination initiators of the Ziegler-Natta initiation type using titanium trichloride-based transition metal initiators modified with dialkylaluminum chloride. To accomplish this polymerization required that the ω-alkenoates be precomplexed with dialkylaluminum chloride. High molecular weight homopolymers and copolymers with olefins have been obtained. The polymerization of ω-epoxyalkanoates with coordinative anionic polymerization systems based on triethylaluminum/water/acetylacetone (1.0/0.5/1.0) has also been accomplished. Homo- and copolymers of high molecular weight and of relatively narrow molecular weight distribution have been prepared. All polymers and copolymers of functional olefins and epoxides have been characterized and the study of the reactivity of the functional groups attached via a flexible spacer to the polymer main chain has been started. Special attention was given to the classical cationic copolymerization of trioxane with derivatives of ω-epoxyundecanoate to prepare novel functional polyoxymethylenes of potential commercial interest.     

Structural Factors Affecting the Basicity of ω-Pyridylalkanols, ω-Pyridylalkanamides and ω-Pyridylalkylamines

The present paper describes the preparation by conventional methods (when not available commercially) and the pK_a-determination of the α-, β- and γ-isomers of pyridylethanamide, 3-pyridylpropanamide. 4-pyridylbutanamide, 5-pyridyl-pentanamide, pyridylmethanol, 2-pyridylethanol, 3-pyridylpropanol, 4-pyridyl-butanol, 5-pyridylpentanol, pyridylmethylamine, 2-pyridylethylamine, 3-pyridyl-propylamine, 4-pyridylbutylamine, and 5-pyridylpentylamine. While a field effect accounts for many variations in pK_a as a function of chain length, marked inductive effects are operative in some methyl and ethyl homologs. The pK_a-decreasing influence of an intramolecular H-bond is also apparent in some lower homologs belonging to the α-series.     

Synthesis and structure of methyl-substituted 1,3-Dioxa-2-Silacylohexanes

The reaction of dimethyl(diethylthio)silane with 1,3-diols gave methyl-substituted 1,3-dioxa-2-silacyclohexanes.¹H and¹³C NMR spectroscopy were used to study the configuration and predominant conformations of the compounds studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 845–851, June, 1986.     

Time-resolved ESR and endor during the photolysis of ω,ω-dimethoxy-ω-phenyl-acetophenone

The ketone ω,ω-dimethoxy-ω-phenyl-acetophenone (DMPA) is an efficient initiator in UV-curing polymerization processes started by photochemically generated radicals. The short-lived radical intermediates created during the photolysis of DMPA have been investigated by time-resolved ESR and ENDOR spectroscopy taking advantage of a strong CIDEP effect.