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To assess the polyhydroxyalkanoate (PHA)-biodegrading capacity of soil, numbers of aerobic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB/V)-degrading microorganisms (degraders) were estimated by the film-MPN method. The numbers of PHB/V degraders were estimated to be 4.3 × 105 per gram of dry garden soil, 5.06 × 105 per gram of dry paddy-field soil, and 3.87 × 105 per gram of dry river-bank soil. The degradations of PHB/V in suspensions of the three kinds of soil were investigated. It was found that the PHB/V-biodegrading capacity of the soil increased as the number of PHB/V degraders in the soil increased. The relationship between weight loss of PHB/V and proliferation rate of PHB/V degraders in garden soil suspension was investigated. The effect of glucose on the biodegradation of PHB/V in garden soil was also studied. The weight loss after one week in garden soil suspension supplemented with 20 mM of glucose (GSS-20G) was 2.60%, which was lower than that in garden soil suspension (GSS) (7.14%). After five weeks, the weight loss had increased to 24.97% in GSS-20G but only to 18.26% in GSS. The results showed that glucose played important roles in inhibition and acceleration of different biodegrading phases and finally accelerated the PHB/V biodegradation in soil suspension. Copyright © 2003 John Wiley & Sons, Ltd.

The effects of glucose and glycine on the biodegradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB / V) in a soil suspension were studied. Relationship between the weight loss of PHB / V and the proliferation rates of the degrading bacteria was investigated. The weight loss after 1 week was 2.60 ± 0.3% in the soil suspension supplemented with 20 mm of glucose (SSS-20G) and 4.76 ± 0.48% in that supplemented with 20 mm of glycine (SSS-20gly). These ratios were lower than that in the control soil suspension (CSS) (7.14 ± 0.93%). After 5 weeks, the weight loss had increased to 24.97 ± 2.25% in SSS-20G and 31.85 ± 2.55% in SSS-20gly but only to 18.26 ± 2.19% in CSS. Nutrients in PHB / V biodegradation play important roles in the inhibition and acceleration of different biodegrading phases and eventually accelerate the PHB / V biodegradation in the soil suspension.

A kinetic investigation on the hydrolysis of aryl(fluoro)(phenyl)-λ6-sulfanenitriles was carried out in some aqueous and mixed aqueous-organic solutions. The pH-rate profiles showed that the hydrolysis consists of pH-independent, acid-catalyzed and base-catalyzed reactions. The neutral hydrolysis of fluoro-λ6-sulfanenitriles was found to proceed via an SN1 or an S-nitrilosulfonium cation-like transition state, which is characterized by a large negative Hammett ρ-value (ρ = −1.76 in water; −1.85 in CH3CN/H2O(1/4, v/v); −2.35 in TFE/H2O (1/1, v/v)), relatively large m-values (ca. 0.83 for fluoro(diphenyl)-λ6-sulfanenitrile; ca. 0.82 for fluoro(p-nitrophenyl)(phenyl)-λ6-sulfanenitrile against the solvent ionizing power YOTs-values in acetonitrile–water), a common ion effect in TFE/H2O, and a small salt effect. The large negative activation entropies (−60 – −101 J K−1 mol−1) were presumed to be due to strong solvation of F− with H2O in the reaction systems. The ease of ion dissociation of the S–F bond was exa...

A Ralstonia sp. strain JC-64 that is capable of accumulating poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P[3HB-co-3HV]) from cottonseed oil and valeric acid was isolated. By using a high limiting-nitrogen (HLN) mineral medium as the medium for the second stage of the fermentation process and by adding the two carbon sources at different times, a range of copolymers with 12–62 mol% of 3HV were produced from a series of HLN mineral mediums containing different compositions of cottonseed oil and valeric acid by Ralstonia sp. JC-64. The melting temperature (T m ) of polyhydroxybutyrate from cottonseed oil was 174°C and that of P(3HB-co-3HV) with the highest 3HV-mol fraction (62%) was 81°C.

The hydrolysis of alkoxy(aryl)(phenyl)-λ6-sulfanenitriles in several buffer solutions was found to follow a good pseudo-first-order kinetic equation, giving the corresponding sulfoximides and alcohols (for the case of the hydrolysis of neopentyloxy-λ6-sulfanenitrile, giving a rearranged product, 2-methyl-2-butanol). The dependence of the rate of hydrolysis on the structure of the alkyl group showed the opposite trend to the usual SN2 character, i.e. Me < Pr < Bu ≈ Et < i–Pr, except for neopentyl. The pH-rate profiles indicated that the rate of hydrolysis is also first order in [H+] at pH more than 6.08, and trends to saturate at low pH. According to these kinetic results, a two-step reaction mechanism was proposed which involves a pre-equilibrium protonation on the nitrogen atom of the alkoxy-λ6-sulfanenitriles, followed by a rate-determining C-O bond cleavage via an SN2 or SN1 mechanism on the alkyl carbon atom depending on the structure of the alkyl group. From a double-reciprocal plot of 1/kobs vs. 1/[...

To develop a simple method to determine the degree of substitution (dS) for starch ester, we prepared starch acetate with various dS values (0—3) and examined the mode of starch-iodine complex formation for the starch acetate by monitoring the ultraviolet-visible (UV-vis) spectra and their Fourier-transform infrared (FT-IR) spectral changes. The effect of acetylation on the formation of the starch-iodine complex was investigated by monitoring the decrease in absorbance at 680 nm (blue value). The blue value decreased by increasing the standard dS value determined by NMR for starch acetate, but two different correlations between the blue values and the dS values were observed for the low- and highly-substituted starch acetate. The FT-IR spectra for starch acetate particles were measured using a diffuse reflection method. The peak areas and absorbances of the bands assigned to the acetyl group showed a poor correlation with standard dS values from the NMR. On the other hand, the FT-IR peaks assigned to sodi...

Previously we reported the novel thioaldehydes generation via thermolyses of phenacyl sulfoxides bearing some heteroaromatics. Thermolysis of sulfoxides (1a,b and 2a-4a) bearing other heterocycles such as thiadiazole, triazole, and tetrazole in the presence of 2,3-dimethyl-1,3-butadiene in dioxane at 100 degrees C led to the unexpected products 6-substituted-5,6-dihydro-3,4-dimethyl-2H-thiapyran 1-oxide (5a,b). These products were considered to be formed by the Diels-Alder reaction of the diene with the sulfines formed initially by the thermal decomposition of the sulfoxides. The rate acceleration and the improvement of the yield by addition of 1.5 equiv of triethylamine, especially in the case of ethoxycabonylmethyl sulfoxide 1c, was observed. The cis-trans selectivity for sulfine cycloadducts was also studied by NMR spectrometry. The reactions of alpha-substituted phenacyl sulfoxides 1d-f bearing a phenyl-substituted tetrazolyl group in the presence of the same diene were also studied.

In the study of the thermolysis of heteroaryl substituted sulfoxides, we examined the same reaction in the presence of several amines, such as aniline, benzylamine, and morpholine. In the case of 5-(1-phenyl)-1,2,3,4-tetrazolylsulfinylmethyl(dimethyl)phosphine oxide ( 1 ), the corresponding phosphinecarbothioamide 2 were unexpectedly obtained in moderate yields together with 1-phenyl-1,2,3,4-tetrazole ( 3 ). These products are considered to be formed by the addition reaction of amines to the sulfine formed initially and then elimination of H 2 O.

The thermal decomposition of melamine produces melame and meleme, while alkaline hydrolysis of melamine produces ammeline and ammelide. These four melamine derivatives were determined by high-performance cation-exchange chromatography using phosphate buffer as the eluent. The elution behavior during the isocratic and gradient elutions was examined and the determination was simultaneously achieved using photodiode array UV–Vis detection. An isocratic elution with 50 mM phosphate buffer (pH 2.5) seemed most suitable for the rapid and quantitative analysis. Three types of gradient elutions involving phosphate- and NaCl-concentrations, and pH also showed satisfactory separations for the melamine derivatives.

S-Alkoxy-S,S-diarylthiazynes were prepared by two methods: the alkaline hydrolysis of S,S-diaryl-N-halosulfilimines in aqueous alcohols and the reaction of S,S-diaryl-S-fluorothiazynes with sodium ...

The protective effect of guanidine hydrochloride (Gu-HCl) on the retrogradation of waxy corn starch (WCS) gel was studied using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and solid-state 1H nuclear magnetic resonance (NMR). The areas of the endothermic peaks on DSC curves attributed to re-gelatinization of WCS gels became small and shifted to lower temperature with increasing Gu-HCl contents; finally, the endothermic peak for WCS gel containing 40% Gu-HCl disappeared, indicating that the WCS gel remained in the gelatinized state. The solid-state 1H NMR and FT-IR spectra for retrograded WCS gels showed significant changes compared with those for gelatinized WCS gels. In the process of retrogradation, these spectral changes should imply the formation of intra- and intermolecular hydrogen bonds of WCS and the increase of free water molecules. However, the 1H NMR and FT-IR spectra for a WCS gel containing 40% Gu-HCl did not show such changes along with the progre...

The pyrolysis of triphenyl (diphenoxyphosphinyl)phosphorimidate ( 1 ) was investigated using differential thermal analysis-thermogravimetry (DTA-TG), thermogravimetry-mass spectrometry (TG-MS), infrared spectroscopy (IR), mass spectrometry (MS), high performance liquid chromatography (HPLC) and the 31 P nuclear magnetic resonance method ( 31 P NMR). The cleavage of 1 by electron impact (EI) was also investigated, the results were used to elucidate the pyrolysis process. Compound 1 decomposed on heating to form phenol, triphenyl phosphate, hexaphenoxycyclotriphosphazene, octaphenoxycyclotetraphosphazene, triphenyl [ N -(diphenoxyphosphinyl)- P , P -diphenoxyphosphinimyl]phosphorimidate and longer-chain phosphazene compound (PhO) 2 P(O)NP(OPh) 2 NP(OPh) 2 NP(OPh) 3 . In mass spectrometric analysis, 1 was cleaved by the elimination of a phenoxyl radical, similar to pyrolysis, the formation of the ion assigned to triphenyl phosphate was observed.

Thermal reactions of phenacyl sulfoxide bearing heterocycles, such as a 2-benzothiazolyl or N-oxypyridyl group, in the presence of 2,3-dimethyl-1,3-butadiene afforded 6-benzoyl-5,6-dihydro-3,4-dimethyl-2H-thiapyran in good yield. This product is considered to be formed by the Diels−Alder reaction of a diene with thioaldehyde formed initially by the decomposition of sulfoxides.

粉末X線回折とフーリエ変換赤外分光分析(FT-IR)を用いて研究した.粘度は保存期間とともに増加した.一方,糊化前にGu-HC1を添加しても粘度は保存期間とともに増加し,添加量が多いほど粘度は低かった.膨潤した粒子の相互作用により,それら粒子は水素結合により網目構造を形成する.デソプンの粘度の増加率の長期的な増加は可逆的な結晶化と,貯蔵中の粒子間内の分子間水素結合と関係する.そこでこれらの老化した糊液の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.また糊化直後と老化後の糊液のFT-IRを測定すると,水素結合を示す3000-3800cm-1の波数でピークの相違を観測し,五つのピークがこの波数内で重なり合っていた.これらの結果から老化の際に,Gu-HC1がワキシコーンスターチの分子構造に与える変化を提案し,模式図として示した.

Combustion tests show that polyamide-6 (PA-6) mixed with melamine is self-extinguishing. The thermal degradation process in PA-6 is modified strongly by the presence of melamine, so that the temperature of decomposition is lowered and the composition of the resulting volatile products is changed. On the other hand, melamine is not effective for either polypropylene (PP) or low-density polyethylene (LDPE). Activation energies based on thermogravimetry (TG) curves for the thermal decomposition of each sample at different heating rates are in the range of about 88.1 to 263 kJ mol −1 . The fluctuations found in activation energies indicates that a charring mechanism may contribute to the overall process. Minor amounts of thermal decomposition products other than ϵ-caprolactam were also evolved from the pure PA-6, their formation being suppressed in mixtures with melamine. The charring process occurs in parallel with the volatilization of decomposition products of PA-6, on which melamine seems not to have a significant effect. It appears evident that, compared with PP and LDPE, PA-6 is much more susceptible to thermal decomposition in the presence of melamine.

Meleme, one of thermal decomposition products of melamine, ws analyzed satisfactorily by high-performance cation-exchange chromatography using 20 m M phosphate buffer as eluent. The elution behavior of meleme and melamine at various pH values (pH 2.0–6.0) was examined and the determination was accomplishes simultaneously using photodiode array UV-Vis detection.

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

Temperature-responsive changes in catalytic properties of enzymes modified with a temperature-responsive polymer, poly(N-isopropylacrylamide) (PIPA), were examined. PIPA with a carboxyl group at its end was prepared using 2,2′-azoisobutyronitrile as initiator in the presence of 3-mercaptopropionic acid as a chain transfer reagent. After being activated by the coupling with N-hydroxysuccinimide, PIPA was directly bound to enzymes such as acid phosphatase and trypsin. The catalytic activities of the modified enzymes showed a bending point in their Arrhenius plots at about 33°C due to a coil-globule transition of PIPA chains. The ratio of amidase- and esterase-activities of trypsin modified with PIPA chains was largely affected by the changes in temperature. As for the semi-enzymatic synthesis of N-benzoyl-L-arginylglycinamide, secondary hydrolysis of the peptide product observed with free trypsin was effectively suppressed in modified trypsin at 45°C (above the transition temperature), and the peptide was obtained with higher conversion.

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‡ = −...

A significant formation of 8-hydroxydeoxyguanosine (8-OHdG) was observed in photoirradiation of “photo-Fenton reagent” (1) with calf thymus DNA in maximum yield of 1.1%. The ten-fold enhancement of the formation of 8-OHdG compared to the control level was observed in photoirradiation of L5178Y cells with 1. The 8-OHdG formation well corresponds to the site specific DNA-cleaving activity of 1 upon photoirradiation.

A macromonomer was prepared from succinimido methacrylate and poly(N-isopropylacrylamide) (PIPA) with an amino end group. The macronomer (MA-PIPA) obtained shows a temperature-responsive transition phenomenon from coil to globule in water at about 36°C. For the copolymer of MA-PIPA with acrylamide (ratio of monomer residues of N-isopropylacrylamide (IPA) and acrylamide (AAm) 10:3), the transition temperature of the PIPA chain was the same as that of the macromonomer, whereas the transition temperature of a linear copolymer of IPA and AAm (ratio of the monomer residues 10:3) was much higher than that of PIPA (52°C). Microspheres were prepared by emulsion polymerization of the macromonomer and styrene in the presence of sodium dodecylsulfate. The microspheres obtained show a temperature responsiveness in the critical flocculation concentration. The macromonomer prepared here can be used as a component of temperature-sensitive devices in various forms.

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.

Thermal reactions of phenacyl sulfoxide bearing heterocycles, such as a 2-benzothiazolyl or N-oxypyridyl group, in the presence of 2,3-dimethyl-1,3-butadiene afforded 6-benzoyl-5,6-dihydro-3,4-dimethyl-2H-thiapyran in good yield. This product is considered to be formed by the Diels−Alder reaction of a diene with thioaldehyde formed initially by the decomposition of sulfoxides.

In the study of the thermolysis of heteroaryl substituted sulfoxides, we examined the same reaction in the presence of several amines, such as aniline, benzylamine, and morpholine. In the case of 5-(1-phenyl)-1,2,3,4-tetrazolylsulfinylmethyl(dimethyl)phosphine oxide ( 1 ), the corresponding phosphinecarbothioamide 2 were unexpectedly obtained in moderate yields together with 1-phenyl-1,2,3,4-tetrazole ( 3 ). These products are considered to be formed by the addition reaction of amines to the sulfine formed initially and then elimination of H 2 O.

Previously we reported the novel thioaldehydes generation via thermolyses of phenacyl sulfoxides bearing some heteroaromatics. Thermolysis of sulfoxides (1a,b and 2a-4a) bearing other heterocycles such as thiadiazole, triazole, and tetrazole in the presence of 2,3-dimethyl-1,3-butadiene in dioxane at 100 degrees C led to the unexpected products 6-substituted-5,6-dihydro-3,4-dimethyl-2H-thiapyran 1-oxide (5a,b). These products were considered to be formed by the Diels-Alder reaction of the diene with the sulfines formed initially by the thermal decomposition of the sulfoxides. The rate acceleration and the improvement of the yield by addition of 1.5 equiv of triethylamine, especially in the case of ethoxycabonylmethyl sulfoxide 1c, was observed. The cis-trans selectivity for sulfine cycloadducts was also studied by NMR spectrometry. The reactions of alpha-substituted phenacyl sulfoxides 1d-f bearing a phenyl-substituted tetrazolyl group in the presence of the same diene were also studied.

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.

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.

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...