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A study on the mechanism of the thermal decomposition of α- and β-heteroatoms substituted ethyl phenyl sulfoxides was carried out using 1-chloroethyl phenyl sulfoxide (1); two diastereomeric 1-acetoxyethyl (substituted phenyl) sulfoxides (2a) and (2b); and 2-chloroethyl phenyl, 2-bromoethyl phenyl, and 2-methoxyethyl phenyl sulfoxides (3, 4, 5). The rate of pyrolysis of 1 was 4.8 times faster at 160°C than that of ethyl phenyl sulfoxide used as a reference, while those of 2a and 2b were 107 and 155 times faster, respectively. The results indicate that the lone pair of electrons on the α-heteroatoms has a larger rate acceleration effect than the electronegativity of them. The substituent effects of the phenyl group of 2a and 2b gave positive Hammett ρ-values (ρ a = 0.76 and ρ b = 0.80 vs. σ). Activation parameters for 2a and 2b are as follows: 2a, ΔH ‡ = 112 kJmol−1, ΔS ‡ = −20 JK−1mol−1; 2b, ΔH ‡ = 107 kJmol−1, ΔS ‡ = −29 JK-1mol−1. Large deuterium kinetic isotope effects for 1-acetoxyethyl-2,2,2-d3 pheny...

The reaction of fluorodiphenyl-λ 6 -sulfanenitrile with primary alkyl- or aryl-amines in the presence of acid catalysts or tertiary- amines gave N-monosubstituted S, S-diphenylsulfodiimides effectively.

The reaction of an N-unsubstituted S, S-diphenyl-sulfimide with aldehydes or ketones in the presence of a borane-pyridine complex and acetic acid in benzene at 40 °C affords the corresponding N-alkyl- S, S-diphenylsulfimides. Since this reaction does not form the N,N-dialkylated aminosulfonium salt, this method provides a convenient preparation of N-monoalkylsulfimides without the necessity for a difficult separation of the products by column chromatography due to their similar R f values. The mechanism of formation is discussed.

The thermal decomposition and mass spectra of the N-phenyl- (1), N,N′-diphenyl- (2), and N,N′,N′-triphenylphosphoric triamides (3) were investigated. DTA-TG/DTG, TG-TRAP-GC/MS measurements, IR spectroscopic analyses, mass spectrometric analyses, HPLC analyses, and a kinetic study were carried out to investigate the thermal decomposition. From the analytical results, it was suggested that 1 decomposed while liberating ammonia and aniline, and condensed in several stages; its thermal products at about 160 °C contained 2. Compound 2 decomposed and condensed to form some condensed products at about 200 °C; its thermal products also contained 3. Compound 3 decomposed while liberating aniline to form a cyclic dimer, while the existence of other thermal products was also observed; the cyclic dimer further pyrolyzed in several stages, and 1 and 2 formed a similar condensed product in the 400 to 500 °C temperature range, though that for 3 was different. In addition, the apparent activation energy of the thermal de...

ポリアミド系樹脂に対し非常に有効な防燃剤であるメラミンシアヌレートの熱分解について研究を行った。メラミンシアヌレートは加熱により徐々に水素結合が伸び, 360℃ 付近でその水素結合の一部が切断される。この温度では,メラミンシアヌレートから対応する等モル量のメラミンとシアヌル酸が生じるわけではない。メラミンシアヌレートの熱分解はアソモニア,水,二酸化炭素,シアン酸,メラミソ,シアヌル酸のような揮発,または昇華化合物の形成を導く。これらのほかに揮発成分としてシアン酸アンモニウムやメラミンシアヌレートの形成が確認された。シアン酸アンモニウムはメラミソシアヌレートから直接生じたのではなく,熱分解で生じたアンモニアとシアン酸との気相反応によるものである。一方,メラミンシアヌレートはそれ自身が昇華して形成したのではなく,熱分解により発生したメラミンとシアヌル酸の気相反応で生じたものである。また,残留したメラミンシアヌレートは 420-450℃ で縮合し, 450℃ 以上で非晶質体へと転換した。メラミンシアヌレートの熱分解挙動を結晶構造,熱分解生成物の観点から議論した。

リン酸二水素グアニジニウム(1)およびリン酸水素ニグアニジニウム(2)の熱分解を検討した。比較のため炭酸ニグアニジニウム(3)と硝酸グアニジニウム(4)の熱分析も行った。TG-DTA 測定では 4 種の試料間に類似性がほとんど観測されなかったが,熱分解で発生した揮発成分の GC/MS 測定では, 4 種共に水,アンモニア,イソシアン酸,二酸化炭素などが検出された。さらに 1 ,2 の揮発成分を冷却固化し, MS および IR にて分析した結果,同様なグアニジソ誘導体の形成が確認された。 1,2 の熱分解残留物の IR 測定では, 300℃ までは異なるスペクトルを示したがそれ以降では同一のスペクトルを示したことから, 300℃ までにグアニジニウムイオン部位の熱分解でビグアニドやアミジノ尿素等のグアニジンおよび尿素誘導体が形成,分解し,ほぼ完全にグアニジニウムイオン部位が消失することが示唆された。さらに 500℃ 以降では,縮合生成したポリリン酸の分解による五酸化ニリソの形成が推測された。また, TG 曲線から算出された活性化エネルギーからも熱分解過程が検討され, 1,2 では重量損失約 20% で活性化エネルギーが最高値となり,その段階における脱水縮合とグアニジニウムイオン部位の熱分解の重複が示唆された。

ワキシコーンスターチ糊液の老化を示差走査熱量測定(DSC)と粉末 X 線回折を用いて研究した。DSC は -15℃ から 15℃ ,および 30 から 100℃ の温度範囲で測定した。糊化直後の糊液では 0℃ 付近に鋭い吸熱ピークが観測され,これ以外に吸熱は観測されなかった。長期放置して糊液が老化すると 50℃ 付近に再糊化の吸熱ピークが観測され,また 0℃ 付近の吸熱ピークは二つに分かれた。これら両者の吸熱ピークは互いに関連しており,ともに老化の結果であると考えられる。一方,糊液を凍結させて放置したところ, 72 日経過しても老化に起因する吸熱ピークは観測されなかった。また,老化した糊液中のワキシコーンスターチの X 線回折を測定すると B 型の結晶構造の回折線が観測された。また 3 種類の濃度の糊液を調製し,老化挙動を比較したところ,老化の速度は著しく影響を受けたのに対し,デンプン乾物量換算した吸熱量はほぼ一定の値になった。このことは糊液老化の機構が濃度により影響を受けないことを示している。これらの結果から糊化,老化の際のワキシコーンスターチの分子構造の変化を提案し,模式図として示した。

The pyrolysis of trimethylsilyl derivatives of saccharides (1) was investigated by DTA-TG, MS, GC/MS and TG-GC/MS. The DTA-TG/DTG curves showed that the pyrolysis of 1 occurred in one stage. The exothermic peaks were due to sublimation or thermal decomposition by vaporization. The cleavage mechanism by electron impact of 1 was classified into four categories: 1) stepwise elimination of the side-chain, 2) cleavage of the side-chain, 3) cleavage of the pyranose ring, and 4) cleavage of the pyranose ring and side-chain at the same time. The mass-spectrum for 1 revealed the main common four fragment ions, such asm/z 73, 191, 204 and 217, with cleavage of the pyranose ring. These fragment ions were detected with a similar retention time in the gas cromatogram by GC/MS or TG-GC/MS. The retention time for 1 increased in the sequence aldopentose

Reaction of 2-methyl-2-propanesulfenic acid (1) with methyl arenesulfenates (2) gave S-aryl 2-methyl-2-propanethiosulfinates quantitatively, and kinetic investigation was carried out. Second-order rate dependence (first-order in methyl benzenesulfenate (2a) and first-order in the sulfenic acid (1)) was observed, and a small activation enthalpy (ΔH‡ = 28 kJ mol−1) and a large negative activation entropy (ΔS‡ = −130 J K−1 mol−1) were obtained. Kinetics for the reaction of trans-decalin-9-sulfenic acid (3) with the sulfenates 2 under acidic conditions in methanol–water gave the observation of the second-order dependence, a small activation enthalpy (ΔH‡ = 30.5 kJ mol−1), a large negative activation entropy (ΔS‡ = −140 J K−1 mol−1), a large negative Hammett ρ-value (ρ = −1.39) and no solvent isotope effect (kMeOH/kMeOD = 1.10—1.14 in the range of 15.64—29.98 °C). Kinetics for acidic hydrolysis of the sulfenate 2 under the same conditions afforded the similar activation parameters (ΔH‡ = 40.7 kJ mol−1, ΔS‡ = −...

The thermal behavior and the cleavage mechanism of the electron impact for 5-phenoxymethyl-3-phenylcarbamoyl-2-oxazolidinones derivatives were investigated by the thermal analysis and mass spectrometry. The values of the activation energy were between 90 and 150 kJ mol−1. The rate of thermal decomposition under a nitrogen atmosphere was rapid compared to the rate under an air atmosphere. The distinctions between the products of pyrolysis and EI-mass fragmentation patterns were investigated from the thermogravimetry-trap-gas chromatography/mass spectrometry measurement.

The reaction of S,S-diphenyl-S-methoxythiazyne with various thiols gave methyl sulfides. Kinetic investigations support a mechanism involving an initial protonation of the thiazyne nitrogen with thiol followed by a nucleophilic attack of thiolate anion on the methyl group.

S,S-Diaryl-S-fluorothiazynes, Ar2SF(≡N), were prepared by the reaction of S,S-diaryl-N-bromosulfilimines with tetrabutylammonium fluoride. The thiazyne structure was assigned by the spectral data, physical properties, and is consistent with reactions with sodium alkoxides and primary amines. The thiazyne prepared previously by Clifford et al. is doubtful.

Reaction of S,S-diaryl-S-fluorothiazynes6) with cyclic secondary amines gave novel thiazynes, the corresponding S-aminothiazynes in good yields. Spectroscopic studies, measurement of pKa values, pyrolysis and alkylation reactions of the aminothiazynes were carried out.

Reaction of 2-methyl-2-propanesulfenic acid (1) with methyl arenesulfenates (2) gave S-aryl 2-methyl-2-propanethiosulfinates quantitatively, and kinetic investigation was carried out. Second-order rate dependence (first-order in methyl benzenesulfenate (2a) and first-order in the sulfenic acid (1)) was observed, and a small activation enthalpy (ΔH‡ = 28 kJ mol−1) and a large negative activation entropy (ΔS‡ = −130 J K−1 mol−1) were obtained. Kinetics for the reaction of trans-decalin-9-sulfenic acid (3) with the sulfenates 2 under acidic conditions in methanol–water gave the observation of the second-order dependence, a small activation enthalpy (ΔH‡ = 30.5 kJ mol−1), a large negative activation entropy (ΔS‡ = −140 J K−1 mol−1), a large negative Hammett ρ-value (ρ = −1.39) and no solvent isotope effect (kMeOH/kMeOD = 1.10—1.14 in the range of 15.64—29.98 °C). Kinetics for acidic hydrolysis of the sulfenate 2 under the same conditions afforded the similar activation parameters (ΔH‡ = 40.7 kJ mol−1, ΔS‡ = −...

Thermolysis of phenacyl sulfoxide bearing some nitrogen-containing heterocycles in the presence of 2,3-dimethyl-1,3-butadiene led to 6-benzoyl-5,6-dihydro-3,4-dimethyl-2H-thiapyran. This product was considered to be formed by the Diels-Alder reaction of the diene with thioaldehyde formed initially by the thermal decomposition of the sulfoxide.

Reaction of S,S-diaryl-S-fluorothiazynes6) with cyclic secondary amines gave novel thiazynes, the corresponding S-aminothiazynes in good yields. Spectroscopic studies, measurement of pKa values, pyrolysis and alkylation reactions of the aminothiazynes were carried out.

2-Methyl-2-propanesulfenic acid readily undergoes self-condensation to give S-t-butyl 2-methyl-2-propane-thiosufinate. Rates of the reaction were measured in aqueous acetonitrile solution by use of NMR and UV spectroscopy. The reaction is second order in the substrate. The half-life in a neutral aqueous solution is about 150 hours at 35°C when the initial substrate concentration is 0.003 M. The rate is proportional to acid concentration in the range 0.004–0.2 M. In alkaline solution, the main reaction is self-condensation but some side reactions also seem to occur. The disappearance of the substrate does not follow satisfactory second-order kinetics, but the second-order rate constants obtained by the time-lag method show a maximum around pH 10–11. The pKa (10.47) of the sulfenic acid was obtained at 14°C from a sig-moid curve of the initial absorbances (240 nm) determined by extrapolation of the time-dependent curve.

Ethyl(Substituted phenyl)sulfonium dicyanomethylides (1) were prepared and pyrolyzed in sealed tubes in benzene. The rate for pyrolysis of the substrate was correlated in a good first-order kinetic equation (γ = 0.999). The rate constant was 11.4 × 10−4s−1 at 150°C. Pyrolysis of (1) was found to proceed about 3 times faster than that of ethylphenylsulfonium bis(methoxycarbonyl)methylide (2). Activation parameters calculated from the Arrhenius equation were as follows: ΔH‡ = 128 (KJ/mol), ΔS‡ = 1.7 J/K/mol (150°C, γ = 0.999), in which the magnitude of activation enthalpy was almost the same as that of (2), while the activation entropy was considerably larger compared with that of ethyl phenyl sulfoxide (-75.1 J/K/mol). Thus, the S—Cα bond of (1) was found to be looser in the transition state. The reactivities of sulfonium ylides, sulfoxides and sulfilimines estimate the magnitude of the activation entropies of the substrates. Substituent effect on the phenyl group afforded a positive Hammett p-val...

The pyrolysis of tetraphenyl imidophosphate (1) was investigated by DTA—TG, IR, 1H- and 31P-NMR, mass spectroscopy, and TG—GC/MS. The DTA—TG/DTG curve showed that the pyrolysis of 1 occurred in one stage. Compound 1 melted at about 110°C and pyrolyzed to polyphosphates accompanied by a weight loss of about 70% in the temperature region from 250 to 450°C. The results of IR, 1H and 31P NMR and TG—GC/MS confirmed that this weight loss could be attributed to the cleavage of the PN bond accompanying the formation of diphenyl phosphoramidate (2) and to the liberation of pyrolysis intermediate substances such as phenol, triphenyl phosphate (3), triphenyl N-(diphenoxyphosphoryl)imidophosphate (4), hexaphenoxycyclotriphosphazene (5), diphenyl hydrogen phosphate (6), and 2. Cleavage of PO(Ph) or (P)OPh bonds is characteristic of fragmentation in the high mass spectrum of 1. Subsequently, the fission species transform to other species forming new compounds. The activation energy of the pyrolysis of 1 was estimated to be 111 kJ mol−1, and that for 2 and 3 to be 151 and 220 kJ mol−1, respectively.

S,S-Diaryl-S-fluorothiazynes, Ar2SF(≡N), were prepared by the reaction of S,S-diaryl-N-bromosulfilimines with tetrabutylammonium fluoride. The thiazyne structure was assigned by the spectral data, physical properties, and is consistent with reactions with sodium alkoxides and primary amines. The thiazyne prepared previously by Clifford et al. is doubtful.

Thermal degradation of poly[1,3-phenylenebis(methylene) adipamide] (MXD-6) was investigated by DTA-TG, FT-IR, TG-GC/MS, and mass spectroscopy. The DTA-TG/DTG curve showed that the thermal decomposition of MXD-6 occurred in two stages. MXD-6 melted at about 235°C and decomposed to the oligomer or monomer with a weight loss of about 40% in the temperature region from 330 to 400 °C during the first stage. A TG effluent gas was collected in a cold trap and then directly injected into a GC for separation, the MS for an unequivocal identification. The eleven effluent compounds from the thermal degradation of MXD-6 were identified. The main fragmentation mechanism by electron impact for MXD-6 consisted of two processes: simple cleavage and a rearrangement reaction. The activation energy of the thermal decomposition was estimated to be 230 during the first stage and 150 kJ mol−1 during the second stage. From the value of the activation energy in each stage, the kinetic data for MXD-6 was elucidated.

The reaction of fluorodiphenyl-λ 6 -sulfanenitrile with primary alkyl- or aryl-amines in the presence of acid catalysts or tertiary- amines gave N-monosubstituted S, S-diphenylsulfodiimides effectively.

The reaction of an N-unsubstituted S, S-diphenyl-sulfimide with aldehydes or ketones in the presence of a borane-pyridine complex and acetic acid in benzene at 40 °C affords the corresponding N-alkyl- S, S-diphenylsulfimides. Since this reaction does not form the N,N-dialkylated aminosulfonium salt, this method provides a convenient preparation of N-monoalkylsulfimides without the necessity for a difficult separation of the products by column chromatography due to their similar R f values. The mechanism of formation is discussed.

Kinetics for the alkaline hydrolysis of S,S-diaryl-N-bromosulfilimines were carried out in aqueous methanol. The observed pseudo-first-order rate constants were found to give a linear correlation w...

Four kinds of 2-oxazolidinone derivatives, (1) [5-phenoxymethyl-3-phenylcarbamoyl-2-oxazolidinone (1a), 2,4-bis(2-oxo-3-oxazolidin-3-ylcarbonylamino)toluene (1b), N,N′-bis(2-oxo-3-oxazolidin-3-ylcarbonyl)-1,6-hexanediamine (1c), and 1,4-bis(3-phenylcarbamoyl-2-oxo-5-oxazolidin-5-ylmethoxy)benzene (1d)], were prepared with the addition of 2-oxazolidinone, 5-phenoxymethyl-2-oxazolidinone (2), and 1,4-bis(2-oxo-5-oxazolidin-5-ylmethoxy)benzene (3) to mono- or diisocyanates by using N,N-dimethylformamide or benzene as solvents and 1,4-diazabicyclo[2.2.2]octane as a catalyst. Compound 1 was found to be thermally stable by thermal analysis. DSC curves of these compounds revealed an endothermic peak due to melting, except for 1d which was obtained from 3. The main fragmentation mechanism by electron impact for 1 was found to consist of two processes: simple cleavage and a rearrangement reaction. Further, each process was followed by cleavage modes. The proportion of fragment ions containing the benzene ring in t...

Thermal decomposition of diphenyl phosphoramidate (1)and phenyl phosphordiamidate (2) was investigated by DTA-TG, IR, 1H NMR, 31P NMR, mass spectroscopy, and TG-GC/MS. The DTA-TG/DTG curve showed that the thermal decomposition of 1 occurred in one stage. Compound 1 melted at about 150°C and decomposed to polyphosphates accompanied with a weight loss of about 60% in the temperature region of 200 to 350°C. It was confirmed from the results of IR, 1H NMR, and TG-GC/MS that this weight loss in TG of 1 is attributed to the liberation of ammonia and phenol and to the production of an insoluble polyphosphate through triphenyl phosphate or a soluble oligophosphate. The fragment ions of diphenyl ether (m⁄z 170) and aniline (m⁄z 93) were recognized in the mass spectrum of 1. This result indicates that phenyl radical and hydrogen atom in both samples transfer between three oxygen atoms and a nitrogen atom around a phosphorus atom. The activation energy of the thermal decomposition was estimated to be 151 kJ mol−1 fo...

Eleven 1,3,5-triazine derivatives were investigated by the use of a thermal-analysis techniques. These compounds showed a remarkable difference in pyrolytic behavior and decomposed thermally by a cleavage of the triazine ring and the liberation of water, isocyanic acid, and carbondioxide. The pyrolysis products were separated and identified by a gas chromatograph coupled to a mass spectrometer. All of the obtained information led to the proposal of a thermal degradation mechanism for the triazine derivatives, which is presented here. The main pyrolysis and fragmentation by electron impact mechanisms were classified into four categories, respectively.

5-(N-p)-Toluenesulfonyl)iminothianthrenes, whose sulfur atoms are oxidized to a sulfoxide or sulfone at the 10-position, were hydrolysed readily in high yield to N-unsubstituted-sulfilimines by using concentrated H2SO4. During hydrolysis, 10-monoxy-5-N-unsubstituted-sulfilimines were obtained as a separable mixture of the cis and trans isomers. The stereochemical interconversion of these compounds was studied under both hydrolytic and thermal conditions and their structures were elucidated by using X-ray crystallography.

The reaction of S,S-diphenyl-S-methoxythiazyne with various thiols gave methyl sulfides. Kinetic investigations support a mechanism involving an initial protonation of the thiazyne nitrogen with thiol followed by a nucleophilic attack of thiolate anion on the methyl group.

The structure of a compound formed during the alkaline hydrolysis of S,S-diphenyl-N-halosulfilimines to the corresponding sulfoximine in methanol was assigned to PhS(OMe)(≡N)Ph, S,S-diphenyl-S-methoxythiazyne, on the basis of spectroscopic analyses and chemical reactions.

Thermolysis of phenacyl sulfoxide bearing some nitrogen-containing heterocycles in the presence of 2,3-dimethyl-1,3-butadiene led to 6-benzoyl-5,6-dihydro-3,4-dimethyl-2H-thiapyran. This product was considered to be formed by the Diels-Alder reaction of the diene with thioaldehyde formed initially by the thermal decomposition of the sulfoxide.

Hydrolysis of trans-9-decalyl methoxymethyl sulfoxide with 7% perchloric acid in MeOH–H2O (2 : 1) gave crystalline trans-decalin-9-sulfenic acid whose structure was confirmed by IR, NMR and mass spectrometry; addition to methyl propiolate affording methyl trans-3-(trans-9-decalylsulfinyl)acrylate.

The effect of pyrolysis of the acyl group substituted on a-position carbon in S-ethyl group of ethyl phenyl sulfoxide was investigated by using two kinds of substrates, l-ethoxycarbonylethyl phenyl sulfoxide (1) and l-ethoxycarbonyl-l-methylethyl phenyl sulfoxide (2) together with 2-methoxycarbonylethyl phenyl sulfoxide (4). The rate of pyrolysis of (1) was found to be about 740 ∼ 890 times faster than that of ethyl phenyl sulfoxide (5), while (2) was 5700 times faster. The rate enhancement effect on α-ethoxycarbonyl group was larger than that on β-methoxycarbonyl group. Large deuterium kinetic isotope effect (k 11/k D = 5.5 for PhS(O)C(CD3)2CO2Et (3)) was observed. Activation energy for (2) is about 110 kJ/mol, which is just about the same as that of (5) (108 kJ/mol), while activation entropy lies in ca. 1 Jdeg−1 mol−1. Hammett plot for substituted (2) gave ρ = 0.69. These kinetic results reveal that the pyrolysis of the sulfoxides proceeds via a loose transition state involving advanced C-S bon...

In order to obtain information concerning the reaction mechanism of the pyrolysis of a sulfoxide bearing an electron-withdrawing substituent on the β-position in the S-ethyl group of ethyl phenyl sulfoxide, 2-(substituted phenyl)ethyl aryl sulfoxides(1) and 2-cyanoethyl (substituted phenyl) sulfoxides(2) were pyrolyzed. The rate-enhancing effect of the β-phenyl group of 1 was small. The activation enthalpy and entropy of 1 were found to be 110 kJ mol−1 and −45 JK−1 mol−1, respectively. Hammett plots for 1 gave positive trends for the substituents, both on the β-phenyl group (ρ=0.76) and on the S-phenyl group (ρ=0.32), though the ρ-value of the latter was about half of the former. On the other hand, the Hammett plot for 2 did not give a straight line, but a concave curve in which a series of substituents from the p-OCH3 to p-Cl groups gave a negative trend (ρ=−0.49), while the p-NO2 group afforded a positive trend. The pyrolytic rate of 2 was found to be about 23-times faster than that of 1 at 100 °C. The ...

1,3-Bis(1-hydroxyalkyl)-2-imidazolidinones (1) were prepared by the reaction of imidazolidinone with propyl-, butyl-, isobutylaldehyde. They were unstable and moisture-sensitive substances, except for 1,3-bis(1-hydroxybutyl)-2-imidazolidinone (1c). In the decomposition by the electron impact of 1 and the dimer of 1c, the molecular ion peak of 1 was not detected. The fragmentation of the imidazolidinone ring was considered to take place after a successive cleavage of the two side chains of 1. The pyrolysis reaction of 1 was found to be a thermal decomposition via a molten state after a condensation reaction. The order of the pyrolysis was calculated on the basis of DSC curves. The condensation stage for 1c apparently obeyed 1/2-order kinetics. From the dependence of the velocity on the temperature in DTA and the thermogravimetric analysis, the activation energy of decomposition was calculated; the value for the former was 67 and the latter 73 kJ mol−1. The mechanism of pyrolysis was supported by the result...

Substituted (RS,SR)-1-phenylethyl phenyl sulfoxides (threo) (XC6H4S(O)CH(CH3)C6H4Y) and some substituted (RR,SS)-sulfoxides (erythro) were prepared and kinetic investigation for the thermal decomposition was carried out at 80.0, 90.0, and 100.0 °C in dioxane. Hammett plots for threo-XC6H4S(O)CH(CH3)C6H5 gave positive ρ-values (ρX=0.60–0.64 at three temperatures), while those for threo- and erythro-C6H5S(O)CH(CH3)C6H4Y snowed V-shape lines with bottoms at the m-OCH3 substituent though the effects of the substituents are small. Meanwhile, large kinetic isotope effects for threo- and erythro-C6H5S(O)CH(CD3)C6H4Y (Y=H, p-OMe, m-Cl) (kH⁄kD=4–6) were observed at all temperatures. The activation energies were in the range of 104–121 kJ mol−1 for all sulfoxides, while the activation entropies were relatively large (7–37 J K−1 mol−1) and were correlated with Hammett σ-values to give small negative trend. Reactions of all erythro-isomers examined were 2–3 times faster than those of the corresponding threo-isomers. ...

The effect on the pyrolysis of the carbonyl group substituted at the α-position in the S-cycloalkyl ring in cycloalkyl phenyl sulphoxides was investigated by using 2-oxocyclohexyl phenyl sulphoxide (1) and 2-oxo-3-methylcyclohexyl phenyl sulphoxide (2). The rates of reaction were correlated with a first-order kinetic equation (r = 0.999). A very large rate enhancement in the pyrolysis of (1) and (2) was observed in comparison with that of ethyl phenyl sulphoxide (3), namely, the relative rates of (1) and (2) were about 2100 and 1600 times larger than that of (3), respectively. The activation energies calculated for (1) and (2) were 108 and 109 kJ/mol, respectively, and their activation entropies were both ca. −11 J K−1 mol−1. A solvent effect on the pyrolysis was not observed, as in the pyrolysis of other sulphoxides. From the results, it was concluded thatthe rate enhancement on substituting a carbonyl group was due to mainly the conjugative effect of the carbonyl group with the double bond developed in the transition state during the pyrolysis.

1,6-Bis(2-oxooxazolidin-3-ylcarbonylamino)hexane (1) was prepared from 2-oxazolidinone and hexamethylenediisocyanurate using triethylenediamine as a catalyst in benzene. A TG effluent gas is collected in a cold trap and then directly injected into a GC for separation, the MS for unequivocal identification. The 13 effluent compounds from the thermal degradation of 1 were identified.

あらかじめ反応系に水を添加した場合には反応の進行の途中で反応速度が増大した。この増速点では反応系の比電導度が増大した。水の添加量が 1mlから 10mlまで増大するにしたがって, 反応が増速点に達するまでに脱水された tert-ブチルアルコール (TBA) は約 27% [(生成オレフィン/使用TBA)mol×100] (触媒 1mol に対して脱水された TBA が 4mol に相当) 値から次第に低下した。添加量が 10ml 以上では増速点は消失した。脱水反応速度に対する水の影響を検討した結果 logk と log[H20]との間にほぼ良好な直線関係がえられた。この関係から水の関与次数として1反応 (反応開始から増速点までの過程) では約 0.3, 反応 (増速点以降の過程) では約 0.2 がえられ, それらの符号はともに負であった。反応次数は両反応過程とも TBA 濃度に対しては1次,触媒濃度に対しては I 反応過程では約3次, II 反応過程では約3.4次であった。反応系に, 副生する水を捕捉する試薬を添加した場合には増速点は認められなかった。そしてその速度式は TBA および触媒の各濃度に対しておのおの1次であることが判った。これらの結果から, 本反応の機構に対する水の作用を考察した。

イソブチルアルコールと無水塩化アルミニウムの反応について, 無水塩化アルミニウム使用量が AlCl3/ROH モル比で 0.30～0.05 の範囲について検討した。その範囲内では, 反応生成物はジクロルアルミニウムイソブトキシドのみで塩化アルミニウム使用量に無関係であった。塩化水素の発生速度より反応の次数, 速度定数, 活性化エネルギーおよび, それらから熱力学的諸量を求めた。また反応系の可視, 紫外および赤外吸収スペクトルを測定した結果, 可視吸収スペクトル λmax 365mμ の強度が, 反応の初期において, 時間とともに増大するのが認められた。これらの結果から反応機構について検討した。