Yasuji Izawa

The photochemical sulphoxidation of n-hexane

Abstract The photochemical sulphoxidation of n-hexane in the presence of acetic anhydride giving hexanesulphonic acid has been examined. A maximum yield of 26% is obtained when the sulphoxidation is carried out with a molar ratio of n-hexane:acetic anhydride of 19:1. An increase in the reaction temperature of 28° serves to increase the yield, and for n-decane the limit is reached at about 80°. The reaction is sensitized with acetophenone or p-chloroacetophenone, while it is inhibited by 2,3-dimethylbutane or 1-hexene. Mechanisms involving simultaneous steps of chain reaction via persulphonate radical and a molecular mechanism via excited sulphur trioxide are discussed. The photochemical primary process in the radical chain seems to involve two simultaneous processes, i.e., the energy transfer from excited sulphur dioxide to substrate followed by the homolytic CH bond fission on one hand, and the formation of alkyl radicals by the abstraction of hydrogen with excited sulphur dioxide on the other.

The photoinduced reactions of benzyl methyl ketone

Abstract The photochemical reaction of benzyl methyl ketone (I) has been studied in n-hexane and t-butanol. The rearrangement products, o -methylacetophenone (II) and/or p -methylacetophenone (III), are obtained in poor yield, together with a reductive dimerization product, substituted pinacol (IV), and derivatives of benzyl radical, bibenzyl (V) and tolune (VI). The ratio of III to V tends to increase with lowering concentrations of reactants, but it is little affected by the irradiation time and reaction temperature.

The photochemical reactions of substituted acetones with triethyl phosphite

Abstract Photochemical reactions of substituted acetones with triethyl phosphite have been studied to investigate the chemical behaviour of the n-π* excited state of the CO group. UV irradiation of an ethereal solution of chloroacetone (Ia) and triethyl phosphite (II) at 20° gives vinyl phosphate (III) and ketophosphonate (IV), together with other by-products. The yield of IV decreases by addition of a radical scavenger, hydroquinone, whereas the yield of III is little affected. Addition of methanol and acetic acid suppresses the reaction. A similar reaction is possible with other substituted acetones. The ratio of [III]/[IV] varies with derivatives of acetones. A probable mechanism is discussed.

The photochemical addition of monochloramine to cyclohexene

Abstract The photochemical addition of monochloramine to cyclohexene in ether at 0° and −40° resulted in the 1:1 adduct, trans -2-chlorocyclohexylamine, together with trans -1,2-dichlorocyclohexane, rans -2-chlorocyclohexanol, 3-chlorocyclohexene, hexanenitrile, 3,3′-bicyclohexenyl and ammonium chloride. The effects of the reaction conditions on the best yield of trans -2-chlorocyclohexylamine (8·2%) was studied. The lower initial concentration of the reactants and the lower reaction temp are effective in raising the yield. A probable reaction scheme leading to the observed products is discussed.

Photochemical ethoxycarbonylmethylation of benzene with ethyl haloacetate in the presence of metallic halides

Abstract Photochemical ethoxycarbonylmethylation of benzene with ethyl haloacetate has been studied in the presence of SbCl 5 , AlCl 3 , ZnCl 2 or FeCl 3 . In all cases, ethyl phenylacetate (2·3–24·4%) was obtained as a sole photoproduct and diethyl succinate, which suggests the formation of an ethoxycarbonylmethyl radical, could not be detected. The similar reaction of toluene in the presence of ZnCl 2 gives ethyl p -tolylacetate (12·8%) without o - and m -isomers. A probable reaction pathway involving photochemical electrophilic substitution is discussed.

the photochemical amination of cyclohexane with hydrazine

Abstract The UV light-induced amination of cyclohexane in a liquid phase at room temp has been studied. The amination with hydrazine forming cyclohexylamine is possible, the best yield being 45% on the basis of hydrazine, one of the by-products being cyclohexanol. The effect of reaction conditions and photocatalysts on the yield of amination has been examined. Initial concentration of hydrazine is important and the lower concentration tends to raise the yield. Zinc oxide is an effective photocatalyst.

The photo-reductions of β-ketophosphonates in ethyl ether

Abstract The photo-reductions of dialkyl β-ketophosphonates and ethyl acetoacetate have been studied in detail. β-Ketophosphonates have been found to be photo-reduced efficiently to form corresponding β-hydroxyphosphonates, the quantum yields for disappearance of ketones being 0·6−0·7. By quenching experiments with piperylene, values for bimolecular hydrogen abstraction rate constants ( k r ) by triplet β-keto esters have been estimated. High quantum yields and k r , values observed in β-ketophosphonates are discussed in terms of intramolecular heavy atom effect and electronic configuration of n-π * triplet states of ketones.

A mechanistic approach to the photo-amination of cyclohexane with hydrazine

Abstract The UV light-induced amination of cyclohexane with hydrazine in a liquid phase at room temperature has been further studied. In addition to the cyclohexylamine produced, bicyclohexyl and cyclohexylhydrazine were detected as by-products. The presence of bicyclohexyl suggests a radical mechanism for the reaction. In spite of the formation of a small amount of cyclohexylhydrazine in this reaction, cyclohexylamine seems to be produced exclusively by coupling of ·NH2 with ·C6H11, because no appreciable amount of cyclohexylamine was detected in the photodecomposition products of cyclohexylhydrazine with or without hydrazine under similar conditions used for the photoamination. A probable mechanism is discussed.

Photochemical reactions of alkylbenzenes with boron tribromide

Abstract The photochemical reaction of toluene with boron tribromide followed by hydrolysis results in the formation of o - (12·7%) m - (7·5%), and p -tolueneboronic acids (54·8%) and a trace of ω-tolueneboronic acid. Ethylbenzene is similarly boronated to give o - (9·9%), m - (3·0%), and p -ethylbenzeneboronic acids (57·6%) together with α-(12·9%) and ω-ethylbenzeneboronic acids (2·6%). In the photoboronation of cumene, o - (1·9%), m - (4·5%), and p -cumeneboronic acids (73·6%) are obtained, but no α-cumeneboronic acid could be detected. Ring substitution, which may proceed via photochemical excitation of CT complexes between alkylbenzenes and boron tribromide, is favored. A small amount of side-chain boronated products is simultaneously obtained by a radical process involving a dibromoboryl radical (·BBr 2 ).

Preparation of Surfactants from Ether-Alcohol

オレフィンのオキソ反応のさい副生するエーテルアルコール (炭素数 15) を原料として, そのリン酸エステルナトリウム塩, 硫酸エステルアミン塩, ポリエチレンオキシド付加体と付加体の硫酸エステルナトリウム塩, およびポリプロピレンオキシド付加体などを合成した。リン酸化剤 (五酸化リン) 対基質とのモル比および温度によって, リン酸のモノアルキルエステルとジアルキルエステルの生成比率がどう変わるかを検討し, その関係式を立てた。またそれら生成物の表面張力, 界面張力, 浸透力, 起ホウカを測定し,その利用についても論及する。