N. I. Shuikin

Chemistry of 1,3-bifunctional systems - Communication 3. Synthesis of substituted 1,3-dioxanes in the presence of cation-exchange resins

1. The authors have studied catalytic and thermal conversions of 1,3-dioxane, 2-alkyl, and 2,2-di-alkyl-1,3-dioxanes in a microreactor in a gas-liquid chromatograph. The effects of temperature, the carrier gas and the structure of the initial dioxane on the splitting rate of the dioxane ring have been studied. 2. An increase in the number of substituants in the 2 position of the dioxane ring and in the molecular weight of the alkyl substituent speeds up conversion. On platinized thermolyte conversion is much faster in hydrogen than in helium. 3. The dioxane ring isomerizes in hydrogen predominantly with opening of the ring at the 3,4 bond.

Reactions of diols and epoxides

1. Various methods for the preparation of 3,3-dialkyl(and aryl)oxetanes were investigated. 3,3-Dimethyloxetane was prepared from the corresponding diol, from the corresponding chlorohydrin acetate, and for the corresponding m-dioxane. The highest yield (54%) was obtained by the use of the chlorohydrin acetate. 2. 3,3-Dimethyloxetane was prepared in 25–30% yield from 5,5-dimethyl-m-dioxane. 3,3-Diethyl-oxetane was synthesized from the cyclic carbonate of the corresponding diol and from the corresponding chlorohydrin acetate, and 3-methyl-3-propyloxetane and 3-butyl-3-ethyloxetane were synthesized from the corresponding chlorohydrin acetates. Yields 70–80%. 3. The various methods of synthesis and their mechanisms are discussed.

Reactions of diols and epoxides Communication 10. Synthesis of 3-alkyl- and 3-aryl-oxetanes

New synthesis of 3-methyl-, 3-ethyl-, 3-propyl-, 3-isopropyl-, 3-butyl-, 3-t-butyl-, 3-cyclohexyl-, 3-phenyl-, and 3-benzyl-oxetanes are described, and their more important physical constants are given. These cyclic ethers can be prepared in fairly good yields (40–60%) from the corresponding chloro acetates.

Diols and epoxides Communication 8. Reactions of isomeric γ-chloro butanol acetates with potassium hydroxide

1. The reactions of 4-chloro-2-butanol acetate (I) and 3-chloro-1-butanol acetate (II) with potassium hydroxide were investigated. From (I) 1,3-epoxybutane is formed in 80–85% yield, but from (II) the yield of 1,3-epoxybutane is low (about 7%), and propene (about 55%), trans-2-buten-1-ol (about 6%), and 3-buten-1-ol (about 17%) are formed. 2. The course of the transformations of a γ-chloro alkanol acetate under the action of caustic alkali is essentially determined by the structure of the compound. For a system with the chlorine atom in a primary position, the main course is the formation of the β-epoxide by the mechanism of intramolecular nucleophilic exchange. In the case of a compound with the chlorine atom in a secondary position the main course is the formation of an olefin and an oxo compound. These two main processes pass through the intermediate stage of a chloroalkoxide. 3. The two main reactions may be accompanied by bimolecular nucleophilic exchange processes—the formation of a 1,3-diol and unsaturated alcohols. In the case of γ-chloro alkanol acetates, with increase in the order of the carbon atom carrying the chlorine atom the intramolecular nucleophilic exchange reaction is displaced toward 1,4- and 1,2-elimination.

Synthesis of γ-keto alcohols and dihydrofurans from 2-furanpropanols

A method was developed for the preparation ofγ-keto alcohols and hence 2,3-dihydrofurans by the catalytic hydrogenation of 2-furanpropanols over platinized charcoal at 220° with formation of acetic esters ofγ-keto alcohols, from which as a result of methanolysisγ-keto alcohols and dialkyldihydrofurans are formed.

Isomerization of tetrahydropyrans

1. The transformations ofα-alkyl-,α-phenyl-, andα-cyclohexyltetrahydropyrans in the vapor phase on a Pt-C catalyst at 340–350° were investigated. 2. α-Alkyl- andα-phenyltetrahydropyrans not only isomerize at the C-O bond, but also undergo partial decomposition to formaldehyde and the corresponding olefin (10–20%). 3. The isomerization ofα-alkyltetrahydropyrans proceeds 70% at the C-O bond not next to the side substituent, and 20% at the other C-O bond, while that ofα-phenyltetrahydropyran proceeds to an extent of 60% at the bond away from it. 4. The cyclohexane ring is dehydrogenated to benzene before isomerization of the tetrahydropyran ring.

Synthesis and isomerization of 2-n-propyl-5-phenyltetrahydrofuran

1. The synthesis of 2-n-propyl-5-phenyltetrahydrofuran was accomplished by catalytic hydrogenation of 1-furyl-3-phenylpropanol-3 in the vapor phase on Pt-C at 220°. 2. 2-n-Propyl-5-phenyltetrahydrofuran is isomerized on Pt-C at 300° with opening of the ring at bothC-O bonds: 48% at the bond next to the phenyl radical, and 10% at the bond next to the propyl radical.

Synthesis of γ-diketones by the method of conjugated hydrogenolysi s

1-Furylbutanol-3 and 1-furylpentanol-3 undergo conversions as the result of conjugated hydrogenolysis with hydrogenation in the vapor phase on skeletal Ni-Al at 240°-the former to hexanedione-2,5, heptanedione-2,5, and octanedione-2,5 in a total yield of 30%, the latter to heptanedione-2,5, octanedione-3,6 and nonanedione-3,6, in the same total yield.