THE POLYMERIZATION THERMOKINETICS OF PYRROLE IN THE PRESENCE OF IRON TRICHLORIDE

The polymerization thermokinetics of pyrrole in the presence of iron trichloride art studied by using a Calvet microcalorimoter. The apparent activation energy, the pre-exponential constant and reaction order of this reaction in the temperature range of 25.2—37℃are 34.5 KJ·mol~(-1), 10~(2.74)S~(-1) and 1 respectively. The activation free-energies of this reaction at 25.2°, 30°and 37℃are 91.8, 92.9 and 94.2 KJ·mol~(-1) respectively.     

A THEORETICAL STUDY OF MECHANISMS IN THE PHOTOCHEMICAL REACTIONS OF FORMING XETENE AFTER THE α-EOND RUPTURE IN CYCLCHEMANONE

ab initio,SCF+CI calculations of the potential energy surfaces and barries in the various paths are presented for the chemical reactions of forming ketene after the a-bond rupture in cyclohexanone,using acetaldehyde as model.The possibilities of the various paths and thansition states of the important paths are discussed.     

REACTIVITY AND STEREOSELECTIVITY IN THE DIELS-ALDER REACTIONS BETWEEN CYCLOPENTADIENE AND SOME α, β-UNSATURATED THIOESTERS

Abstract

Some new norbornene thioester derivatives of endo configuration are sinthesized. Proofs are provided that thioester group has more preference for endo configuration than the ester group.     

CONCENTRATION, SOURCE OF MANGANESE AND IRON IN FERROMANGANESE NODULES AND THE RELATIONSHIP BETWEEN NODULES AND SEDIMENTARY ENVIRONMENTS IN NORTH PACIFIC REGION

The concentration, source of manganese and iron in ferromanganese nodules and therelation between nodules and sedimentary environments are discussed in detail by asynthetical study on chemical information of ferromanganese nodules and correspondingsediment, pore water and geological, biological (bacteria) information in 26 stations fromthe North Pacific region (7- 13°N, 178- 165°W). The result shows that (i) the concen-tration and distribution characteristics of magnese and iron in ferromanganese nod-ules differ in different types of nodules, however, the concentration decreases with theincrease in grain sizes of nodules; (ii) the source of iron in different types of nodulesis basically the same, i. e. the slow sedimentation of overlying water; (iii) manganesein nodules comes mainly from the diffusion of Mn~(2+) in the pore water, and Mn~(2+) fromthe reduction of Mn~(4+) in sediments by the medium of bacteria. As the distribution of bac-teria is believed to be strongly affected by the sedimentary envi     

THE PHOTOCHEMICAL SYNTHESIS OF THE PYRIDINE ADDUCT OF TETRAPHENYLPORPHYRINATORHODIUM(Ⅱ)AND THE MECHANISM OF PHOTOCHEMICAL REACTION

A new rhodium(Ⅱ)porphyrin complex was isolated by chromatography from the photochemical reac-tion of(μ—tetraphenylporphyrinato)bis[dicarbonylrhodium(Ⅰ)]with pyridine in benzene and has been charac-terized.From the results,the reaction mechanism is proposed.     

FACTORS IN THE CONTROL OF PRODUCT COMPOSITION IN THE REACTIONS OF TRIALKYL PHOSPHITES WITH α-HALOGENOACETOPHENONES IN ALCOHOLIC MEDIA

Abstract

α-Hydroxyphosphonates are formed, in addition to vinyl phosphates and dehalogenated ketones, in the reactions of trimethyl phosphite (in methanol) or triethyl phosphite (in ethanol) with variously substituted α-chloro, α-bromo, and α,α-dichloro-acetophenones. Tri-isopropyl phosphite in propan-2-ol gives only the vinyl phosphate. Ketophosphonates are not detectable amongst the reaction products under the conditions used. Trends in product composition can be correlated with the leaving ability of halogen, substituent effects, structure of the phosphite, and reaction temperature. Additional products are obtained in the reactions of trimethyl phosphite in methanol with 4-nitro-α-chloroacetophenone, which gives the dehalogenated hydroxyphosphonate, and with the α,α-dichloroacetophenones which undergo monodehalogenation. Twenty three new α-hydroxyphosphonates are reported.     

SEPARATION OF IRON AND MANGANESE IN THE EARLY DIAGENETIC PROCESSES AND ITS MECHANISM OF BIOGEOCHEMISTRY

Study shows that the reduction of iron (Fe~(3+)) and manganese (Mn~(4+)) in modern sedi-ments and the diffusive flux of the Mn~(2+) from the pore water into the overlying waterare mainly controlled by bacteria, and the distribution of the bacteria is believed to beaffected strongly by the sedimentary environment. It is the diffusive fluxes between Fe~(2+)and Mn~(2+) that lead to the separation of iron and manganese in the modern sediment at theChangjiang Mouth and near the shore. The level of the separation decreases with theincrease of the overlying water salinity and increases from the surface to the depth. Thismechanism has given a new explanation why manganese is concentrated in sediments onthe oceanic floor of ferromanganese-rich nodules.     

STUDY OF THE REACTION BETWEEN α-KETOTHIOANILIDE AND PHENYLENE DIAMINE

When α-ketothioanilide reacts with o-phenylenediamine,there aretwo competing reactions.One is condensation which forms substituted quinoxalineand the other is substitution which forms substituted quinoxaline-2-thione·Bycontrolling the reaction condition,we can obtain either quinoxaline orquinoxaline-2-thione as the main product.     

INSERTION REACTION OF CARBOETHOXYLCARBENE TO N-HEXANE IN THE PRESENCE OF BENZOPHENONE AND THE SENSITIZED PHOTO-OXIDATION OF N-HEXANE

In the presence of protosensitizer-benzophenone, ethyl diazoacetate was photolyzedand the resulting carboethoxylcarbene reacted with n-hexane. The result was compared withthat done without the sensitizer. It was revealed that the nature of the insertion products andtheir relative proportions remained the same, whether the sensitizer was presentor not. At the same time, the influence of oxygen on the sensitized and unsensitized inser-tion reaetions was also studied; these showed also no influence on the nature of insertionproducts and their relative proportions no matter whether the sensitizer or oxygen was pres-ent or not. Since oxygen ks a well-known seavenger for the triplet state carbene, the ex-perimental results indicate clearly that the insertion reactions are conducted by the carbenein singlet state. The photo-oxidation products of n-hexane sensitized by air in the presence of benzophe-none were carefully studied, showing that the primary hexyl radical seemed to be rearrang-ed to thermodynamicall     

THE PHENOMENON OF THE FLUORESCENCE PHOTOCHEMICAL ENHANCEMENT AND ITS KINETICS

This paper reports a fluorescence enhancement phenomenon concerning the 2-p-nitro-phenyl-5-biphenyloxazole (NPBO). Although the NPBO solution gives only a weak fluores-cence, yet by introducing some nonfluorescence organic amine, e.g. tri-n-butyl amine (TBA)into this solution, the fluorcscence will be enhanced tens or hundreds times through the ir-radiation. This phenomenon is a new one, different from that as stated by other authors.According to the spectral analysis and the kinetics research, its mechanism may be prelimi-narily suggested as follows: the NPBO may absorb the photons to form a certain intermediatewith less polarity, which might react with the amine to form a stronger fluorescence substance.Such a phenomenon may be called the fluorescence photochemical enhancement (FLPCE).In addition, the rate constants of this process are also dotermined.     

REACTIONS BETWEEN BORIC ACID AND POLYHYDROXY COMPOUNDS AND THE DEVELOPMENTS OF BORON－SELECTIVE RESINS

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REACTIONS BETWEEN BORIC ACID AND POLYHYDROXY COMPOUNDS AND THE DEVELOPMENTS OF BORON—SELECTIVE RESINS

A Review with 56 references on the reaction between boric acid and polyhydroxy compounds,and the developments of boron-selective resins.     

CATALYTIC SYNTHESIS OF α-CYANO-α,β-UNSATURATED SULPHONES IN THE PRESENCE OF ORGANOTELLURIUM OXIDE

Using bis(p-methoxyphenyl)telluroxide(BMPTO)as the catalyst,phenylsulphonyl acetonitrile condensed easily with aromatic aldehydes atroom temperature to give -cyano- ,β-unsaturated sulphones in high yields.     

THE EFEFCT OF MAGNETIC FIELD ON POLYMERIZATION OF STYRENE IN THE PRESENCE OF POLYVINYL NAPHTHALENE AND POLYVINYL BENZOPHENONE

In the process of bulk photopolymerization of styrene initiated by AIBN decomposition polyvinyl benzophenone (PVB) can supply an effective cage for triplet-triplet energy transfer between PVB macromolecules and small molecules of AIBN to influence the molecular weight of polystyrene in weak magnetic field (less than 0.035T), that was different from the case of polyvinyl naphthalene (PVN) which supplied cages for this system only in the stronger magnetic field (more than 0.2 T) studies. It was found that in the same conditions, PVN could exert more tremendous influences on the bulk photopolymerizatiou system of styrene than PVB because in the stronger magnetic field the triplet PVN had much longer life time than PVB.     

MECHANICAL AND THERMAL STRUCTURE OF A CYLINDRICAL PLUME IN THE EARTH'S MANTLE

A mantle plume is understood as a hot, narrow, upwelling flow in the earth's mantle and accompanied by an efficient transfer of mass and energy from deep to upper layer of the earth. The cylindrical plume in earth's mantle plays an important role in explaining the origin of the surface hot spots and linear island chains. From the basic hydrodynamical equations, the detailed mechanical and thermal structure of a cylindrical plume of Newtouian fluids with temperature and pressure-dependent viscosity are given in the present paper. For two sets of rheological parameters the radial profiles of upward velocity, temperature and viscosity in the plume and radiuses of the plume at various depths have been calculated.     

PHOTO-CIDNP STUDIES OF PHTHALIMIDE DERIVATIVES IN THE PRESENCE OF TRIETHYLAMINE

The photoreactivity of some phthalimides was tested by CIDNP studies on the reactionswith triethylamine.     

MONOALLYLATION OF SYMMETRIC DIKETONES IN THE PRESENCE OF WATER BY ALLYLIC BROMIDE AND METALLIC ZINC

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THE RELATION BETWEEN THE DIMENSIONS OF BOUNDARY AND PHASE BOUNDARY IN ISOBARIC PHASE DIAGRAMS

The relation between the dimensions of boundary and phase boundary in isobaric phase diagrams has been proved theoretically in this paper.     

CATALYTIC CRACKING OF LIGHT ALKANES IN THE PRESENCE OF O_2 AND SELECTIVE CONTROL OF OLEFIN PRODUCTS

lntroductionThesmallolefinslikeethylene,propeneandbutenearethec0mmerciallydesirablepetrochemicalfeedstocksandarefoundincreasingusageinchemicalindustry.Theyareusuallyobtainedfromthepyrolysis0fpetroleumhydrocarb0nswithsteaInatveryhightemPeratUreandarealsoavailablefromFCCprocess.TheimProvedFCCcatalystforeIhancingtheolefinproducthasbeenreportedll].However,FCCisalrnostimPossiblefortheshortchainalkanefeedstockscutfrompetroleum0robtuinedfromrefinerygasornatUralgassincecrackingofhydrocarbonsbeco…     

A COMPARISON BETWEEN THE pzc AND iep OF α-FeOOH AQUEOUS SUSPENSION

The salt titration of goethite((?)-FeOOH)aqueous suspension hadbeen carried out with the addition of solid NaCl at several different star-ting pH values and the point of zero charge(pzc)was estimated.Then theelectrophoretic mobilities of positively charged (?)FeOOH particles dispersedin NaCl solution were measured as a function of pH to obtain the isoelec-tric point(iep).The two parameters were compared.