Kazuo Fukuzumi

Transfer hydrogenation and transfer hydrogenolysis: VIII. Hydrogen transfer from amines to olefins catalyzed by heterogeneous and homogeneous catalysts

Abstract It was found that Pd-carbon, Pd-asbestos, and Pd-black have high catalytic activity in the hydrogen transfer from indoline to cycloheptene. RuCl 2 (PPh 3 ) 3 , RhCl 3 · 2H 2 O, IrCl 3 , (NH 4 ) 2 PdCl 4 , and RhH(PPh 3 ) 4 also showed high activity. The hydrogen-donating ability of organic compounds in the hydrogen transfer reaction catalyzed by Pd-carbon decreased in the order: indoline > formic acid > tetrahydroquinoline > piperidine > pyrrolidine > cyclohexene > N -methylpyrrolidine > di- n -propylamine > d,l -limonene > 1,2-dihydronaphthalene, etc. Though monoenes were hydrogenated efficiently, 1,3- and 1,5-cyclooctadiene were reduced to cyclooctene in high selectivity. The initial rate of the hydrogen transfer from indoline to cycloheptene was proportional to the amine concentration at first and then became independent of the amine concentration. The rate showed a maximum when the olefin concentration was varied. This result indicates the poisoning effect of the olefin.

Synergistic antioxidant effect of nucleic acids and tocopherols

Abstract and SummaryNucleic acids acted as synergists with tocopherols in inhibiting the oxidation of methyl linoleate. DNA and RNA enhanced the activity of tocopherols to different extents in the order α->γ->δ-tocopherol. Nucleic acids decreased the rates of consumption of tocopherol in the presence of oxi-dizing methyl linoleate. Nucleic acids also decreased the rate of oxidation of tocopherols by PbO2. The synergistic effect of nucleic acids seemed to be caused by hydrogen bond formation with tocopherols which protected toco-pherols from direct air oxidation.

Transfer hydrogenation and transfer hydrogenolysis—21 : Dehydrogenation of alcohols by quinones

Abstract Dehydrogenation of benzyl-type alcohols and hydroaromatic compounds by 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tetrachloro-p-benzoquinone were examined, and the hydrogen transfer from 1-phenyl-1-propanol to DDQ was investigated in detail. The yield of the propiophenone increased when solvents which would be expected to increase the concentration of the charge transfer complex between the alcohol and DDQ were used. Initial rates of the reaction in dioxane were proportional to the concentration of the hydrogen donor and that of the hydrogen acceptor. In the dehydrogenation of several para- or meta-substituted 1-phenyl-1-propanols at 60°, −3.30 was obtained as a value of reaction constant. Relative rates of the reaction of PhCH(OH)Et, PhCH(OD)Et, PhCD(OH)Et, and PhCD(OD)Et were 8.9,9.1,1.0 and 1, respectively. This result suggests that the transfer of the H atom attached to the α-carbon of the alcohol is the rate-determining step. This and some other results support a two-step ionic mechanism for the dehydrogenation of alcohols.

Transfer hydrogenation and transfer hydrogenolysis : XXII. Hyrogenolysis of triphenylphospine coordinated to transition metals by hydrogen transfer from organic compounds

Abstract When heated with some organic compounds, the triphenylphosphine ligand of RuH 2 (PPh 3 ) 4 , RhH(PPh 3 ) 4 , RuCl 2 (PPh 3 ) 3 , and RhCl(PPh 3 ) 3 were hydrogenolyzed almost completely to benzene and those of PtCl 2 (PPh 3 ) 2 , Pt(PPh 3 ) 4 , and PdCl 2 (PPh 3 ) 2 underwent this conversion to a considerable extent. In the reaction of RuH 2 (PPh 3 ) 4 in pyrrolidine the amount of the benzene formed was about three times as much as that of the triphenylphosphine consumed. Biphenyl was detected in the reaction of the Ru 11 -species. In the hydrogen transfer from 2-propanol and 2-propanol- d 8 no primary kinetic isotope effect was observed, and the cleavage and oxidative addition of PC bonds of phosphine ligands was inferred to be the rate-determining step of the reaction.

Study on the effect of antioxidants in the autoxidation of methyl nonconjugated octadecadienoates

Many studies have been published on the effect of antioxidants on unsaturated fatty acid esters but the differences of the effects of antioxidants on geometric isomers have never been investigated. In this study, methylcis-9,cis-12-octadecadienoate and itstrans isomer methyltrans-9,trans-12-octadecadienoate were used as methyl nonconjugated dienoates, and BHA, BHT, PG, NDGA, 4,4′-dihydroxy-3,5,3′,5′-tetratert-butyl diphenyl methane, L-thyroxine sodium salt,a-tocopherol and sesamol were used, as antioxidants. The differences of the effects of antioxidants on both geometric isomers were investigated by determining the induction period using the weighing method. Also determined were the infrared and ultraviolet spectra, peroxide values, conjugated diene contents, isolatedtrans double bond contents and molecular weights for the controls and the samples containing antioxidants. Thecis,cis isomer was more easily autoxidized and had a shorter induction period than thetrans,trans form. By the end of the induction period, no isolatedtrans double bond forms in thecis,cis isomer, but a considerable amount of isolatedtrans double bond decreased in thetrans,trans isomer. In general, the effects of antioxidants, except NDGA, on thecis,cis isomer were larger than thetrans,trans form.

Effect of organic additives having functional groups in olefin metathesis

Abstract The dependence of product yields on the amount of various organic additives containing heteroatom functional groups was investigated for the metathesis of 2-heptene in benzene at room temperature catalyzed by WCl 6 SnBu 4 (1:1). Without additives, heptylbenzenes were major products, and 5-decene and 2-butene were minor ones. With increasing amounts of ethers, ketones, sulfides, pyridine, amines, a cyanide, an amide, a sulfoxide, a tertiary phosphine, and alcohols, the yield of 5-decene first increased markedly and that of heptylbenzene decreased; thereafter, the yield of 5-decene was also lowered. When reaction temperatures were elevated to 80 or 120 °C, the amount of the additives needed to inhibit metathesis increased. In particular, for ether and ester addition significant metathesis was observed even at an additive/catalyst ratio of 30. This suggests that the metathesis of unsaturated ethers and esters proceeds rather efficiently. A comparison of the relative ability of these additives to inhibit metathesis and alkylation shows that the active species in the former reaction are softer acids than those of the latter. It was shown that additives raise metathesis yields mainly by protecting the active species of metathesis from decay, although the inhibition of the alkylation may also have some effect on the yields. The decay of metathesis species takes place easily in a medium where the alkylation proceeds well.

Transfer hydrogenation and transfer hydrogenolysis: XII. Selective hydrogenation of fatty acid methyl esters by various hydrogen donors

The selective hydrogenation of methyl linoleate was studied using various organic compounds as hydrogen sources in the presence of homogeneous and metallic palladium catalysts. Complete selectivity to monoenes and relatively little formation of isolatedtrans double bonds were realized by the hydrogen transfer from L-ascorbic acid at 47% conversion of starting material to hydrogenation products. The hydrogenation bytrans-1,2-cyclohexanediol catalyzed by RuH2(PPh3)4 also showed rather high selectivity tocis-monoenes. In the reaction catalyzed by RuH2(PPh3)4, also showed rather high selectivity tocis-monoenes. In the reaction catalyzed by RuH2(PPh3)4, the presence of these hydroxy compounds increased the isomerization of methyl elaidate tocis-monoenes.

Olefin metathesis and side reactions with the binary systems of WCI6 and metal alkyls

Abstract The comparison of the behaviors of the WCl6-metal alkyl systems (metal alkyls are Bu4Sn, Et2Zn, Et3Al, and BuLi) was carried out in the metathesis of 2-heptene in benzene. The WCl6Et2Zn and the WCl6BuLi systems showed the sharp dependence of metathesis on the co-catalyst/WCl6 ratio, whereas the WCl6Bu4Sn and the WCl6Et3Al systems did the dull one. The yield of the Friedel-Crafts products, heptylbenzenes, increased with a decrease in the co-catalyst/WCl6 and the olefin/WCl6 ratios, though the WCl6BuLi system barely catalyzed this side reaction. A proper amount of dicyclopentadiene, phenylacetylene, ethyl ether, ethanol, and esters repressed the Friedel-Crafts reaction, and the metathesis products were obtained in high yield and high selectivity in the metathesis of 2-heptene catalyzed by the WCl6Bu4Sn system.

The effect of sensitizing dyes for photo as antioxidants on the autoxidation of methyl linoleate

The sensitizing dyes for photo which are cyanine homologues have been used as medicine and cosmetics. Their uses are widespread. The authors expected that these dyes might serve as antioxidants by a radical termination mechanism such as hydroperoxy radicals added to the many conjugated double bonds which exist in the dyes. Determination of the induction period by the weighing method confirmed that some sensitizing dyes for photo are available as antioxidants in the autoxidation of methyl linoleate. Therefore, these dyes may serve as new types of antioxidants.

Quantitative determination of methyl octadecadienoate hydroperoxides by infrared spectroscopy

The determination of peroxide values has been used for many years to estimate the concentration of the -OOH group in hydroperoxides formed during autoxidation of unsaturated fatty acid esters. Generally a considerable amount of a sample is required for this determination. The thiobarbituric acid test for estimating oxidative deterioration in various fats has also been used but mainly to determine malonaldehyde in an oxidized sample. From the IR spectra of fatty acid methyl esters, -OOH groups can be detected, but not estimated in general, because of association of the -OOH groups by hydrogen bonds. The present study shows that the -OOH group, even in small amounts of intact methyl octadecadienoate hydroperoxides, can be quantitatively determined by IR spectroscopy using a 1 cm cell (100 times the depth of usual cells) and a solution usually of concentration 1:100. Thus, a new quantative determination method for the -OOH group by IR spectroscopy has been developed.