KINETIC STUDIES ON THE ACID-CATALYZED PUMMERER REACTION OF α-(METHYLSULFINY)ACETOPHENONES

Abstract

The kinetic behavior of the acid-catalyzed Pummerer reaction of α-(methylsulfinyl)acetophenones in dilute hydrochloric acid has been studied in detail. The kinetic data were analyzed in the light of correlations between the reaction rates and acidity functions, activation parameters, solvent isotope effects, polar effects of substituents, etc. Moreover, ¹⁸O-tracer experiments were also carried out using acid media containing H₂ ¹⁸O. Based on these observations, a plausible mechanism for this reaction has been discussed.     

STUDIES ON THE REACTION MECHANISM OF ORGANIC HYDROPEROXIDE AND AMINE SYSTEM INITIATED POLYMERIZATION

The initiation mechanism of organic hydroperoxide and amine system has been investigatedsystematically in this paper. It has been confirmed from the IR spectra that organic hydro-peroxide could form hydrogen-bonded complex with amine. The reactive intermediate of theamine and its effect on initiating polymerization have been determined by using ESR techni-que, and further proved by the results of polymer end group analysis and graft copolymeri-zation of vinly monomer onto the amino-containig polymer. Finally, water, as one of the finalproducts of ROOH-amine reaction has been detected through chromatographic analysis, fromwhich the conversion reaction of the reactive intermediate is verified.     

STUDIES ON THE REACTION OF ORGANOTELLURONIUM SALTS

The structural studies of the telluronium saltrformation betweendibutyl telluride and secondary (?)-bromo compounds and the use of the obtai-ned salts for the olefination of carbonyl compounds were reported.     

KINETIC STUDIES ON THE POLYMERIZATION OF ACRYLONITRILE INITIATED BY METALLIC MAGNESIUM-NITRIC ACID SYSTEM

This article reports the polymerization kinetics of acrylonitrile initiated by metallic magnesiumnitric acid system. The rate of polymerization is independent of the amount of magnesium used; when the concentration of nitric acid is higher than acrylonitrile, the equation of polymerization kinetics may be expressed asR_p =1.91×10~5e~(-15000)/RT[Mg]~0 [AN]~(2.2) [HNO_3]~(0.45)The result of copolymerization of acyrlonitrile and methyl acrylate supports a free-radical mechanism.     

AB INITIO STUDIES ON THE REACTION MECHANISH OF CYCLOADDITION OF KETENE AND FORMALDEHYDE

The cycloaddition reaction of ketene and formaldehyde,lesding to 2-oxetanone,has been studied theoretically by means of RHF/3-21G.This reactionis believed to be nonsynchronous but concerted,taking place through a twistedfour membered ring transition state.Two types of frontier orbitalinteractions are involved in this reaction.The activation barrier iscalculated to be 123.1KJ/mol (MP2/3-21G result).     

STUDIES ON THE PHOTOCHEMICAL REACTION OF TERTIARY AROMATIC AMINES AND ALIPHATIC HALIDES——STRUCTURE OF THE PRODUCT AND MECHANISM OF THE REACTION

The photochemical reaction of aromatic amines in the presence of aliphatic halides and molecular oxygen were studied. There is a very obvious structural effect of amines on the photoreactions, and the purple products, formed only in the tertiary aromatic amines system, were proved to be amiuium radical salts, e. g. CH_3—(CH_3)_2Cl-by moans of UV, NMR and ESR spectroscopies electronic conductivity and chemical analysis. The purple product can oxidize the adrenaline to adrenochrome. The mechanism of the photoreaction and the oxidation were discussed.     

THE KINETIC STUDIES ON THE PHOTOISOMERIZATION OF 1,2-DISUBSTITUTED ETHYLENES

An NMR study on the kinetics of photoisomerization of some important 1,2-disubstitutedethylenes are presented in this study.     

MCSCF STUDIES ON THE IRC AND REACTION RATE CONSTANTS FOR THE DEHYDROGENATION REACTION OF VINYL RADICAL

The transition state(TS) and Intrinsic Reaction Coordinate (IRC) for the titled reaction were traced by means of MCSCF/6-31G (210 configurations). The reaction activation energy of this reaction is 140.2KJ/mol. The reaction rate constants of five temperetures were calculated by CVT involving the tunneling effects.     

STUDIES ON THE REACTION OF d-ACETAMIDCCINNAMAMIDE WITH TRIS(DIETHYLAMINO)PHOSPHINE

d-Acetamidocinnamamide do not react with P(OMe)_3, with P(NEt_2)_3 they give rise to 2-methyl-4-hydroxy-5-d-[bis(diethylamino)phosphoryl] benzyl imidazole.The pathway is studied for the formation of Ⅰ. The two intermediates(Ⅱ) are isolated.The structures of Ⅰ and Ⅱ are confirmed by IR, ~1H NMR, ~(31)P NMR, Ms.     

STUDIES ON POLYHALOALKANES Ⅳ. THE REACTION OF POLYFLUOROALKYL IODIDES WITH SILVER(I) SALTS

The conversion of polyfluoroalkyl iodides into the corresponding carboxylic acids by the reaction with silver (I) salts is described.     

PRELIMINARY STUDIES ON THE KINETIC RESOLUTION OF METHYL ERYTHRO-PHENYLGLYCERATE AND METHYL t-EPOXYCINNAMATE BY PLE

PLE(pig liver esterase) catalyzed hydrolysis of the title compounds demonstrated that the α-carbon with S configuration hydrolyzed faster than the R configuration and α-carbon controlled the stereoselectivity. The preliminary results showed that the highest ee obtained were only 40-48%.     

STUDIES ON THE VOLTAMMETRIC BEHAVIOR OF EU(Ⅲ)-ALDOPENTOSE AND EU(Ⅲ)-D-RIBOSE-L-AMINO ACIDS COMPLEXES

The rate of voltammetric reduction of Eu(Ⅲ)in acetate solutionwas increased by the formation of a complex with ribose,lyxose orarabinose.If a ternary complex of Eu(Ⅲ)-D-ribose-L-phenylanaline formed onthe surface of mercury electrode,the redox process of Eu(Ⅲ)became morereversible than that of Eu(Ⅲ)-D-ribose in solution phase.     

STUDIES ON THE OXIDATION AND GRAFT COPOLYMERIZATION OF POLY(ETHER-URETHANE)

A new method of graft copolymerization of acrylamide (AAM) on poly(ether-urethane) (PEU) which was prepared from poly(tetramethylene ether) glycol (PTMG), 4,4'-diphenylmethane diisocyanate (MDI) and ethylene diamine or butanediol extender was investigated. Hydroperoxide group was first introduced onto the surface of PEU through photo-oxidation in the presence of hydrogen peroxide, then it was reacted with ferrous ion or N,N-dimethyl toluidine (DMT) to initiate AAM graft copolymerization on PEU surface. The graft reaction could be carried out effectively at low temperature. The formation of graft copolymer has been verified by its water absorption % and the scanning electron microscopy photographs. Some model compounds of PEU soft segment and hard segment were synthesized in order to clarify the site of graft reaction. The results of oxida-tion and graft copolymerization of model compounds showed that this graft copolymerization possesses higher selectivity, and it takes place predominately at the polyether segments, because the ether linkage in soft segment is very sensitive to oxidation and can form hydroperoxide easily. Thus, the grafting site appears to be at α-carbon of the ether linkage.     

STUDIES ON THE ORGANOSILICON REACTIVE INTERMEDIATES——Ⅳ.GENERATION AND REACTION OF CYCLOPROPYLPHENYLSILYLENE BY PHOTOCHEMICAL METHOD

In the chemistry of silylene and carbene,owing to the special abilities of cyclo-propyl containing silylenes and carbenes,they have attracted many organic chemistsattention.In carbene chemistry,the ring-expansion and fragmentation of cycloprop-ylphenylcarbene gave out the cyclobutene derivative and alkyne and ethylene.Inorder to find out the reaction products of its counterpart silylene,the cyclopropylp-henylsilylene was investigated.     

STUDIES ON THE MESOZOIC MARGINAL ARC SYSTEM OF THE SOUTHEAST COAST AND TAIWAN IN CHINA

The southeast coastal Zhejiang, Fujian, Guangdong provinces and Taiwan in China comprised an important area in ancient Asia where the Yenshanian continental margin magmatic arc well developed in the late Mesozoic time. It is believed that the oceanic trench and subduction zone are situated on the east side of the Central Range in Taiwan. It seems unlikely that the so-called Hercynian-Indosinian ancient island arc folded system would have occurred in this region.     

THEORETICAL STUDIES ON THE CYCLOADDITION REACTION OF FLUOROKETENE WITH ETHYLIDENIMINE

ＴＨＥＯＲＥＴＩＣＡＬＳＴＵＤＩＥＳＯＮＴＨＥＣＹＣＬＯＡＤＤＩＴＩＯＮＲＥＡＣＴＩＯＮＯＦＦＬＵＯＲＯＫＥＴＥＮＥＷＩＴＨＥＴＨＹＬＩＤＥＮＩＭＩＮＥＴＨＥＯＲＥＴＩＣＡＬＳＴＵＤＩＥＳＯＮＴＨＥＣＹＣＬＯＡＤＤＩＴＩＯＮＲＥＡＣＴＩＯＮＯＦＦＬＵ...     

STUDIES ON THE TOTAL SYNTHESIS OF MAYTANSINOIDS (Ⅳ)——SYNTHESIS OF MAYTANSINE

This paper reports the total synthesis of optically pure maytansinol and maytansine. The physical constants and spectral data including R_f, m.p., specific rotation, HPLC, UV, CD, IR, NMR, and MS, of synthetic maytansinol and maytansine are identical with those of natural products in all respects. The preliminary biological test showed that synthetic maytansine possesses the same inhibitory activity in vitro against carcinoma cells as the natural product.     

STUDY ON THE REACTION OF ACYLISOCYANATE AND ARYL UREA

Acyl isocyanate(Ⅰ) was synthesized by the reaction of acyl chloride with lead cyanate in dichloromethane, using pyridine as a catalyst. Then, adding aryl urea(Ⅱ) to acyl isocyanate, 1-acyl-5-aryl-biuret (Ⅲ) can be obtained. 14 compounds have been synthesized by this method.     

KINETIC STUDIES OF HAEMOPOIETIC PROGENITOR CELLS (CFU-C) AND T-LYMPHOCYTES IN THE LIVER OF HUMAN FOETUS

In the development of human foetus. liver is an important haemopoietic organ. Wehave determined the liver weight and total hepatic nucleated cells from 24 foetuses on the onehand, and CFU-C yield, total number of CFU-C and T-lymphocytes in liver from 22 foetuses ofdifferent ages on the other. From the kinetic observations through the early developmental period of the foetuses. themaximum yield of CFU-C or the total numer of CFU-C in the liver occurs at 4--5 months ofgestation; during the first 5 months of gestation the percentage of T-lymphocytes in the liveris about 1--2%.     

STUDIES ON THE PHOTOPOLYMERIZATION OF ACRYLONITRILE INITIATED BY BENZOPHENONE-ANILINE SYSTEM

The photopolymerization of acrylonitrile initiated by benzophenone-aniline system wasstudied under the irradiation at 365 nm. From the kinetic data measured in dimethylforma-mide the kinetic equation was presented as R_p∞[benzophenone]~(0.32) [aniline]~(0.27) [acryloni-trile]~(1.1). The rate of polymerization for different amines was in the following sequence, i.e.N, N-dimethylaniline>N-methylaniline>aniline. The influence of the polarity of solventwas investigated, from which we proposed that the proton transfer took place in the intimateradical-ion pair state of the exciplex between benzophenone and aniline. Among the twokinds of radicals produced the anilino radical is responsible for the initiation.