ADDITION OF SULPHENYL CHLORIDES TO ACETYLENES. STRUCTURE OF THE INTERMEDIATE

Abstract

Sulphenyl chlorides react in sulphur dioxide with acetylenes to give thiirenium chlorides 1 which lead to the final adducts 2.     

A NEW TYPE OF PHOTOCHEMICAL ADDITION REACTION OF ELEMENTAL SULFUR TO OLEFINS

Abstract

Photochemical reactions of elemental sulfur with several olefins were studied. Irradiation of a mixture of elemental sulfur and norbornylene with 3500 Å light afforded 3,4,5-trithiatricyclo[5.2.1.0]decane (1) and 2,3-epithionorbornane (2). Similarly, several thiane derivatives (4–6) were found to be formed by the photolysis of a mixture of cyclohexene and sulfur.     

THE MECHANISM OF PHOTOCHEMICAL ADDITION OF CYSTEINE TO URACIL AND FORMATION OF DIHYDROURACIL

Abstract— A proposed mechanism for the photochemical addition of L -cysteine to uracil with the concurrent formation of dihydrouracil is shown to proceed through the triplet excited state of uracil which can abstract hydrogen atoms from cysteine to form dihydrouracil. This triplet state is the same one as that leading to photodimerization. The thiyl radicals generated add to ground state uracil molecules. The data permit a re-evaluation of the quantum yield for intersystem crossing of uracil in water which shows dimerization in aqueous solution to have a maximum efficiency of 56 per cent. The formation of the cross-adduct and dihydrouracil may be sensitized but the efficiency of the reaction is related to the ability of the sensitizer to be photoreduced and not to its triplet energy.     

硫化氢对二茂铁乙烯基芳酮亲核加成反应的研究

关于二茂铁基与羰基相连的α,β-不饱和劳酮和硫化氢的亲核加成反应,我们曾有过报导。研究表明,由于二茂铁基的影响使该类加成反应与Michael加成反应规则不同。本文继续研究三茂铁基与烯基相连的α,β-不饱和芳酮和硫化氢的亲核加成反应,制得了四种尚未见报导的β-二茂铁基-β-或α-巯基丙酰基芳烃:     

ON THE MECHANISM OF PHOTOCHEMICAL ALKYNE INSERTION INTO CYCLOPENTADIENYLIRONDICARBONYL DIMER: ALKYNE ADDITION TO A “TIED-BACK” Cp-Fe DIMER

Abstract

The photochemical insertion of phenylacetylene with the “tied-back” dinuclear complex [(η⁵-C₅H₄)₂SiMe₂]Fe₂(CO)₂(μ-CO)₂ (4) yields, by X-ray structural analysis, a dimetallacyclopentenone product entirely analogous to that obtained from the photochemical reaction of the alkyne with (η⁵ - C₅H₅)₂Fe₂(CO)₂(μ-CO)₂ (1). This result is interpreted as evidence for an alternative pathway for photochemical alkyne addition to 1. Attempts to identify the photochemical intermediates from 4 have been unsuccessful. A competition study between 1 and 4 indicates that photochemical alkyne insertion into 1 is preferred by approximate ratio of 2:1 over insertion into 4.     

溴代二苯酮与丙腈负离子的光诱导加成反应

<正> 芳香卤代物芳环上的卤原子在光诱导或电引发下可通过自由基链式亲核取代反应(S_(RN)|)而被有机负离子所取代。 我们以3-溴苯基-苯基-甲酮为底物,在丙腈碳负离子存在下进行光照,结果芳酮环上的溴原子未发生 S_(RN)|取代,而是在羰基上发生了光诱导加成反应,生成了未见文献报道的新化合物1-苯基-1-(3-溴苯基)-2-氰基丙醇-1(I)     

铁钴双金属催化剂上二氧化碳加氢合成低碳烯烃

研究了常压下铁钴双金属催化剂上二氧化碳催化加氢合成低碳烯烃的反应,考察了钴含量、反应温度对二氧化碳转化率、产物选择性的影响。结果表明,钴的添加有利于铁的碳化,提高了二氧化碳转化率,降低了一氧化碳选择性,提高了甲烷选择性,适量钴的添加促进了二氧化碳向烃的转化。在铁钴摩尔比６７∶３３,反应温度３５０℃,反应空速５０００ｍｌｇ－１ｈ－１条件下,二氧化碳转化率达到２８１％,Ｃ＋２选择性达到１１６％,烯烷比５     

PHOTOCHEMICAL ADDITION OF GLUTATHIONE TO URACIL AND THYMINE

Abstract —Irradiation (Λ > 240 nm) of thymine in aqueous solution in the presence of glutathione produces primarily 5-S-glutathione-5, 6-dihydropyrimidine and 5- S, S -glutathione-5, 6-dihydro-pyrimidine. These adducts are obtained in better yields when the irradiations (Λ > 280 nm) are carried out in the presence of triplet-state sensitizers. Reduction of 5- S, S -glutathione-5, 6-dihydropyrimidine with zinc dust in acetic acid yields the corresponding 5, 6-dihydropyrimidine. When thymine-glutathione adducts are heated in 6 N HCl for 2h, 5- S -cysteine-5, 6-dihydrothymine and 5- S, S -cysteine-5, 6-dihydrothymine are formed. Under these conditions, uracil-glutathione adducts are less stable and are converted to products other than uracil-cysteine adducts.     

CaO固硫反应机理研究的新进展

CaO固硫反应的机理研究一直是高温钙基固硫的难点，最近研究认为CaO固硫反应分为两个阶段：前期为表面化学反应阶段，后期为产物层扩散控制阶段。前期反应生成的CaSO4不仅堵塞了CaO颗粒之间的微孔，也逐渐包覆了CaO颗粒，致使后阶段固硫反应转化率明显降低。传统上认为是SO2和O2通过CaSO4产物层向内扩散与CaO进行反应，依此机理提出了核收缩模型和等效粒子模型。新的研究结果认为，固硫反应后期的产物层扩散控制阶段，主要发生的反应是Ca2+通过产物层CaSO4扩散至表面与SO2和O2进行反应，而与传统的机理不同。本文主要介绍了两种实验技术在CaO固硫机理研究中的应用，并在实验现象基础上，对固硫机理提出了新认识。最后对在CaO中添加了不同添加剂能明显提高固硫率的试验数据作了新的机理解释。     

STEREOCHEMISTRY OF THE ADDITION OF PENTAFLUOROTHIOPHENOL TO ALKENES AND ACETYLENES

Abstract

Leong and Peach (J. Fluorine Chem., 6, 145 (1975) have shown that at room temperature pentafluorothiophenol readily reacted with 1-hexene and phenylacetylene forming adducts, the reactions following anti-Markovnik type regio-selectivity, and suggested a free radical mechanism.     

高反差显影机理

剂或显影液中添加防灰雾剂或麟化合物。分析这两种化合物提高反差的作用机理就不难看出高反差显影在机理上存在着共同的特点。本文着重高反差显影共同特点的讨论,有关防灰雾剂及麟化合物在高反差显影过程中作用机理的详细讨论将在另文中进行。     

显影机理的正电子化学研究

采用正电子湮没技术(PAT)研究了照相明胶中的自由体积空穴在显影过程中的作用机理,为显影过程中银丝的生成机理探讨了一个新的模式,并为感光科学的研究拓展了一种新的研究技术和手段.结果表明:明胶的自由体积空穴的平均尺寸在显影过程中基本保持不变.照相明胶的自由体积空穴在电子密度空间限制了银离子还原为银原子的过程,并使得银原子的沉积生长以丝状的形式进行.照相明胶大分子结构和组份的复杂性导致了其自由体积空穴在空间分布无序混乱性,可能正是这种无序混乱性导致了银丝缠绕成团的松散空间结构.     

PHOTOCHEMICAL ADDITION OF AMINO ACIDS AND PEPTIDES TO DNA

Abstract— The quantum yields for photochemical addition of twenty of the amino acids commonly occurring in proteins to denatured calf thymus DNA have been determined in deoxygenated phosphate buffer at λ 254 nM and pH 7 using a fluorescamine assay technique. Fifteen were found to be reactive, with cysteine, lysine, phenylalanine, tryptophan and tyrosine being the most reactive. Alanine, aspartic acid, glutamic acid, serine and threonine were unreactive. Analogous quantum yields for a series of eighteen peptides of the form glycyl X (X being one of the commonly occurring amino acids) were also determined, along with the corresponding quantum yields for L-alanyl-L-alanine, L-alanyl-L-tryptophan, L-seryl-L-seryl-L-serine, L-threonyl-L-threonyl-L-threonine, and L-cystine- bis -glycine. All of the peptides were found to be reactive. The modified amino acids N^ε-methyllysine, N^ε, N^ε, N^ε-trimethyllysine and N^ε-acetyllysine, all occurring in minor amounts in the histone group of chromosomal proteins, were also found to be reactive as was N^α-acetyllysine. The quantum yields for photoaddition of a selected group of amino acids and peptides to denatured DNA and native DNA are compared. In some cases higher quantum yields for photoaddition to denatured DNA are observed while in other cases the reverse is true. The effect of oxygen on the quantum yields for photoaddition of selected peptides to DNA was examined. While for most systems studied the amount of reaction in aerated systems was less than in deoxygenated systems, in the case of glycyl-L-phenylalanine the reverse was true.     

磷酸钙骨水泥水化机理研究进展

本文综述了Ca(H2PO4)2·H2O-Ca3(PO4)2-Ca4(PO4) 2O,Ca4(PO4)2O-CaHPO4,α-Ca3(PO4)2-少量β-TCP、HAP,β-Ca3(PO 4)2-CaHPO4·H2O-CaCO3及α-Ca3(PO4)2-Ca(H2PO4)2·H2O -CaCO3等几种主要磷酸钙骨水泥体系的特点和水化机理研究进展.     

粘度法研究壳聚糖对外加盐的敏感性

聚电解质的特性粘度对外加盐的响应是反映聚电解质对外加盐敏感性的一个重要特征，通过分别测定壳聚糖在不同小分子强电解质（ＮａＣｌ、ＫＣｌ、ＣａＣｌ２、ＢａＣｌ２）和相同小分子强电解质（ＮａＣｌ）但不同离子强度的稀溶液粘度，得到：（１）壳聚糖特性粘度与外加盐的离子强度的平方根的倒数成正比；（２）不同小分子强电解质中阳离子对壳聚糖特性粘度的影响次序是Ｎａ＋＞Ｋ＋＞Ｂａ２＋＞Ｃａ２＋．同时，测算了壳聚糖在不同外加盐浓度中的Ｍａｒｋ Ｈｏｕｗｉｎｋ方程参数α，发现其值皆大于０５，得到了壳聚糖分子链的僵硬性参数Ｂ的值为００７４，揭示了壳聚糖具有较大的分子链刚性和抗盐性能．     

1,2-ARYL MIGRATION AND EXPERIMENTAL EVIDENCE FOR A TWO-STEP MECHANISM IN THE ELECTROPHILIC ADDITION OF BENZENESULFENYL CHLORIDE TO OLEFINIC SYSTEMS

Abstract

Reactions of 2-methyl-3-arylbut-1-en-3-ols (VIII) with benzenesulfenyl chloride were found to give both normal adducts (IX and X) and 1,2-rearrangement products (ketones XI). Yields of XI depend on the electron-releasing effect of the substituents in the benzene ring of VIII. Fairly good correlation of the rate constants with ω° are found, resulting in a ρ ω° equal to -0.83. Tetraethylammonium and especially lithium perchlorate addition were found to lead to a sharp increase in the quantity of the rearrangement products (XI). Solvolysis of the adducts IX and X produced enhanced yields of XI as compared with the addition reactions. These facts are clearly consistent with (i) the occurrence of a 1,2-aryl migration in the fast non-limiting step and (ii) suggest a two-step mechanism involving an intermediate with a low degree of positive charge development at the carbon atoms in the rate-determining step.     

固载化催化剂在烯烃氧化合成醛酮中的应用

总结了固载化催化剂在烯烃氧化合成醛酮中的应用。着重介绍了钯配合物固载在无机载本上,钯盐和杂多化合物固载在无机载体上,钯盐固载在化催化剂在烯烃氧化合成醛酮中的应用。对负载型液相催化剂,负载型水相催化剂,负载型熔融盐Wacker催化剂,活性C固载的Pd膜及Pt膜催化剂催化烯烃氧化合成醛酮也作了简单介绍。     

PHOTOCHEMICAL ADDITION OF L-LYSINE TO 1,3-DIMETHYL-4-THIOURACIL*

Irradiation of an aqueous solution of 1,3-dimethyl-4-thiouracil (1) in the presence of l -lysine ( 2 ) with a high-presure mercury lamp through a Pyrex filter gave a 1:1 mixture of two photoproducts. One of the products was isolated in a pure form, which on treatment with acetic anhydride-pyridine yielded the starting material 1. Based on the spectral data (¹H and ¹³C NMR) and the chemical reaction, the structure of the photoproduct was assigned to 3. The photochemical reaction is considered as a nucleophilic addition of l -lysine to photoexcited 1.     

PHOTOCHEMICAL ADDITION OF AMINO ACIDS AND PEPTIDES TO POLYURIDYLIC ACID

Abstract— The quantum yields for photochemical addition of glycine and the L-amino acids commonly occurring in proteins (excluding proline) to polyuridylic acid have been determined in deoxygenated phosphate buffer at pH 7, using a fluorescamine assay technique. All twenty amino acids were found to be reactive, with cysteine, tryptophan, phenylalanine, tyrosine, arginine, lysine and methionine being the most reactive. The analogous quantum yields for a series of eighteen dipeptides of the form glycyl X (X being one of the commonly occurring amino acids, including proline), of L-alanyl-L-tryptophan, of the tripeptides L-seryl-L-seryl-L-serine and L-threonyl-L-threonyl-L-threonine, of the tetrapeptide L-cystine- bis -glycine, and of the lysine derivative N_α-acetyllysine were also measured. All were found to be reactive toward photoaddition to poly U.     

KINETIC STUDIES ON THE ADDITION OF p-TOLUENESULFINIC ACID TO BENZYLIDENEACETOPHENONES

Abstract

Kinetics of the addition of p-toluenesulfinic acid to p-substituted benzylideneacetophenones has been investigated. The reaction was second order, first order each in the concentration of sulfinic acid and chalcone. Effects of the p-substituents on the reaction rate were small (rho = 0.4). The reaction was strongly acid catalyzed.