Kunio Itabashi

A Facile Synthesis of Thioacids by Hydrolysis of 1-(Acylthio)ethaniminium Chlorides

A facile method for the preparation of thioacids in moderate to good yields has been developed by hydrolysis of 1-(acylthio)ethaniminium chlorides under a liquid-liquid two phase system consisting of benzene and a sodium hydroxide aqueous solution at room temperature. We have achieved facile preparation of these compounds without use of toxic compounds such as hydrogen sulfide.

Reaction of Phthalic Thioanhydride with Aliphatic Amines

Phthalic thioanhydride (PTA) was allowed to react with aliphatic amines in ether at room temperature to give 1:2 adducts in good yields(Ta1e 1). Upon heating the 1:2 adduct above its fusion point, phthalic acid diamide was produced with evolution of hydrogen sulfide, The 1:2 adduct was decomposed by acid to produce PTA. ln the case of the reaction of PTA with aromatic amines, such an adduct was not formed. The reaction with aniline did not give an adduct but N-phenyl phthalimide.

Hydrogenations of Benzyl Alcohol, Benzaldehyde and Benzonitrile with the Molybdenum Trisulfide Catalyst

三硫化モリブデン触媒を用い,ベンジルアルコール(I),ベンズアルデヒド(II)およびベンゾニトリル(III)の,水素圧30kg/cm2,温度160～250℃における水素化反応について検討した。これら試料はいずれも水素化開裂をうけ易く,主としてトルエンを生成したが,一方においては二量体を副生した。特にIIからはペンゾイン,meso-ヒドロベンゾイン,trans-スチルベンおよびビベンジルのような二量体が比麟的に多く副生した。みかけの初期反応速度はII>III>Iの順で,Arrheniusの式にしたがって求めたみかけの活性化エネルギーはそれぞれI:E160～220℃=14.3kcal/mol,II:E160～190℃=8.5kcal/mol,III:E200～250℃=3.9kcal/molであった。反応あ初期においては,これら水素化反応はいずれの場食も水素圧に関してほぼ1次であり,また試料濃度に関してはそれぞれIIはほぼ1/2次,IおよびIIIは0次であった

Pressure-catalytic hydrogenation of Organic Compounds by Molybdenum Sulfide Catalyst. XIII

The reaction of preparing dodecanthiol by catalytic hydrogenation (reductive thiolation reaction) of dodecanoic acid with sulfur, in cyclohexane under pressure has been investigated by using MoS3 catalyst.The reaction was proceeded above 200°c and gave dodecanthiol as the main product with a small amount of di-dodecyl disulfide as a by-product. It was advantageous to heat at about 250°c for this reaction and the amount of sulfur had great effect on the velocity of reaction. In case of 3.0 molar ratio of surfur with the reaction time of 240 min at 250°c, 90% yield of the thiol was obtained. It, was indicated from the result of similar reaction on dodecanoic anhydride and hydrogenation of thiododecanoic acid that the reducive thiolation reaction of dodecanoic acid consisted of the formation of thionic acid from reaction of H2S with dodecanoic acid and its rapid cleavage into the thiol.

Pressure-hydrogenation of Organic Compounds by Molybdenum Sulfide Catalyst. X

Catalytic reduction of p-toluenesulfonic acid derivatives and p-toluenesulfinic acid with molybdenum sulfide catalyst at high prsssure and their reductive cleavages have been investigated.Although the temperature of reaction became higher in order of p-toluenesulfonyl chloride, sulfinic acid, ethyl ester, amide, 4nd phenyl ester, even the last phenyl ester was almost completely cleaved to toluene at 300°C and it was indicated that the reduction was proceeded much easier than sulfonic acid.The final product was toluene and the yield was higher than 80% in case of amide and phenyl ester but the yield was lower in case of chloride, ethyl ester and sulfinic acid.By consideration of the fact that p-thiocresol and di-p-tolyl disulfide were obtained as the intermediate products in each case, the reductive cleavage was assumed to proceed through the following reductive condensation reactions: p-toluenesulfonic acid derivatives→sulfinic→acid→disulfide→thiocresol→toluene.

Pressure-hydrogenation of Organic Compounds by Molybdenum Sulfde Catalyst. VI

Ctalytic reduction of dithiodiglycolic acid was carried out with molybdenum sulfide catalyst at high pressure.The reaction was started at around 100°C with an initial pressure of hydrogen at 50 atm and gave thioglycolic acid as a main product.The maximum yield was 64.3% at 130°C but it was mixed with unreacted sample.Reduction to acetic acid was accompanied with an increase of temperature and nearly all was converted into acetic acid at 180°C.Comparison of the resul with that of general disulfides indicated that the cleavage of S-S bond of dithiodiglycolic acid was proceeded at low temperature and the mercapto group of thioglycolic acid formed also showed a tendency of cleavage to acetic acid the yield of thioglycolic acid was low for this reason. Comparison of result oi similar reduction of β-dithiodipropionic acid indicated that a characteristic reductive reaction of dithiodiglycolic acid was assumed to the effect of carboxy, group in α-position against the sulfur atom.

Pressure-hydrogenation of Organic Compounds by Molybdenum Sulfide Catalyst.VIll

Conditions for obtaining of η-dodecylmercaptan (2) by the reduction of di-η-dodecyl disulfide (1) with pressure in the presence of molybdenum trisulfide (MoS3) catalyst have been investigated.The cleavage of (1) to (2) began at around 1200C, the yield of (2) reached to above 92% at 120-200°C and dodecane was formed above 250°C. An increase of reaction temperature and initial pressure was effective for acceleration of reaction, gave a slight increase in yield of (2) and decreased the amount of unreacted (1).There was practically no side-reaction product and this method is considered to be an excellent one as the yield of (2) exceeded 95%.Nearly the same results were obtained by using recovered MoS3, MoS2 and (NH4) 2MoS4 catalysts, while using of MoO3 was unsatisfactory as it required to heat at high temperature for reaction.

Pressure-hydrogenation of Organic Compounds by Molybdenum Sulfide Catalyst. V

Catalytic reduction of disulfides consisting of a pair of the same octyl, dodecyl, benzyl, phenyl or p-tolyl radicals was carried out with molybdenum trisulfide catalyst and hydrogen with an initial pressure at around 100 atm at various temperatures. Each of these disulfides showed the cleavage of S-S bond at 130-140°C and gave mercaptans with good yield.The mercaptans formed in the intermediate stage were further decomposed at above 200°C to give hydrocarbons and the cleavage was almost completed at around 300°C.The same results were obtained by use of mercaptans as the sample.

Pressure-hydrogenation of Organic Compounds by Molybdenum Sulfide Catalyst.II

Catalytic reduction of α-naphthonitrile with molybdenum sulfide was carried out in liquid phase with pressure.Reaction at above 240°C with an initial pressure at 100 atmospheres of hydrogen yielded approximately 90% of α-methylnaphthalene. Heating with the temperature at below 200°C resulted in the recovery of starting material while the reaction above 200°C gave mostly α-methylnaphthalene. In either case, the yield of amine was very small and it was found that the nitrile group was cleaved to methyl group.There was no formation of naphthalene by the liberation of nitrile group.Similarly, benzonitrile yielded toluene in good yield.