共查询到20条相似文献，搜索用时 62 毫秒
1.
| 1. | 1,2-Oxathiolan-5-one-2-oxides are readily cleaved by nucleophiles (H2O, ROH, HNR2) under mild conditions at the O-CO bond only, with the formation of the -(hydroxysulfinyl)-alkanoic acid derivatives. |
| 2. | 2,1-Benzoxathiol-3-one-1-oxide is cleaved by alcohols at both the O-CO and the O-SO bonds to give the unstable monoesters at the carboxyl and sulfinyl groups. |
| 3. | Unlike 2,1-benzoxathiol-3-one-1-oxide, 1,2-oxathiolan-5-one-2-oxides on boiling with excess alcohols give -(hydroxysulfinyl)alkanoic acid bisesters. |
2.
G. S. Kalinina E. A. Shchupak N. S. Vyazankin G. A. Razuvaev 《Russian Chemical Bulletin》1976,25(6):1289-1292
| 1. | Tris[tris(trimethylsilylmethyl)stannyl]- and tris[tris(trimethylsilylmethyl)germyl] thallium, the first stable compounds containing Sn-Tl and Ge-Tl bonds, have been prepared by the reaction of the hydrides of tris (trimethylsilylmethyl)tin and tris (trimethylsilylmethyl)germanium with triethylthallium. |
| 2. | The Sn-Tl bond is attacked in the reactions of the stannylthallium compound with lithium, mercury, oxygen, bromine, ethyl bromide, ethanol, and other reagents. |
3.
K. A. Andrianov M. M. Il'in V. N. Talanov I. I. Zhurakovskaya 《Russian Chemical Bulletin》1976,25(11):2432-2435
| 1. | The coammonolysis of SiCl4 and Me3SiCl leads to a mixture of tris(trimethylsilylamino)silylamine (I), tetrakis(trimethylsilylamino)silane (II), and also cyclodi- and cyclotrisilazanes. |
| 2. | Additional treatment of the mixture with Me3SiCl increases the yield of (II). |
4.
| 1. | The condensation of 1,2-hydroxylamino oximes with biacetyl leads to 1-hydroxy-2-acetyl-2,4,5,5-tetrasubstituted 3-imidazoline 3-oxides. |
| 2. | When 1-hydroxy-2-acetyl-2,5,5-trimethyl-4-phenyl-3-imidazoline 3-oxide is oxidized the CH3CO group is cleaved to give the 5H-imidazole 1,3-dioxide. |
| 3. | Stable nitroxyl radicals were obtained when the 1-hydroxy-2-oximiaoethyl-2,4,5,5-tetrasubstituted 3-imidazoline 3-oxides are oxidized. |
5.
| 1. | A series of C-functional derivatives of (3)-1,2-dicarbaundecaborate was synthesized and some of their properties were studied. |
| 2. | Apparent ionization constants of acids of the (3)-1,2-dicarbaundecaborate series were measured and it was found that they are very weak carboxylic acids. |
| 3. | Upon reaction with excess LiA1H4, under mild conditions the carbonyl, *20c \CH(OH) / \begin{array}{*{20}c} \backslash \\ {CH(OH)} \\ / \\ \end{array} , and CH2OH groups of dicarbaundecaborate ketones and alcohols are reduced to CH2 and CH3 groups, respectively. |
| 4. | The effect of Grignard reagent on ketones and esters of the dicarbaundecarbprate series was studied and it was established that the composition of reaction products depends both on the steric hindrance of the carbonyl group and on the electron-donating effect of the (3)-1,2-dicarbaundecaborate substituent. |
6.
L. A. Rozov Yu. V. Zeifman N. P. Gambaryan Yu. A. Cheburkov I. L. Knunyants 《Russian Chemical Bulletin》1976,25(12):2560-2566
| 1. | Depending on the nature of the substituent in the 2 position, l-fluoro-l-(-hydrohexafluoroisopropyl)ethylenes are dehydrofluorinated to either allenes or 1,3-dienes. |
| 2. | It was shown that allylic substitution is possible in the reactions of perfluoroisobutylene with carbanions; the mutual transformations of the allyl and vinyl isomers were studied. |
| 3. | The perfluoroalkenylation product was obtained when perfluoroisobutylene is reacted with ketene acetal. |
7.
| 1. | From MNDO quantum chemical calculations, opening of the episulfonium ion ring by neutral nucleophiles X (X=NH3 and HCN) and related SN2 reactions of protonated methylthiol (PMT) with X proceed through formation of pre-reaction complexes in which X is coordinated either at the reacting C atom or (only in opening of episulfonium ion rings) at the center of the C-C bond. |
| 2. | In their electronic structure, the transition states for the reactions are reminiscent of a carbocation simultaneously reacting with the attacking and the leaving nucleophilic fragments (X S). |
| 3. | Opening of episulfonium ion rings proceeds slightly more easily (Ea 10–12 kcal/mole) than substitution in PMT (Ea 22–25 kcal/mole). The ease of ring opening for episulfonium ions is due to the large exothermicity of the reaction and the lower internal activation barrier compared with SN2 reactions in PMT. |
8.
I. E. Chlenov I. M. Petrova V. M. Shitkin V. A. Tartakovskii 《Russian Chemical Bulletin》1976,25(6):1347-1350
| 1. | The reaction of 6-nitro-2,9-dioxa-1-azabicyclo[4.3.0]nonane derivatives with alcohols and alcoholates leads to remplacement of the nitro group by the corresponding alkoxy group. |
| 2. | The reaction proceeds with either a complete (for the case of the alcoholates) or predominant (for the case of alcohols) inversion of the configuration at the substitution center. |
| 3. | The reaction proceeds via the intermediately formed bicyclic immonium cation. |
9.
K. V. Komarov N. D. Chkanikov V. I. Suskina A. B. Shapiro A. F. Kolomiets A. V. Fokin 《Russian Chemical Bulletin》1989,38(2):415-417
| 1. | The alkylation of 2,2,4-trimethyl-1,2-dihydroquinoline and its derivatives by hexafluoroacetone occurs regioselectively and leads, depending on the conditions, to 6-(2-hydroxyhexafluoro-2-propyl)-2,2,4-trimethyl-1,2-dihydroquinolines or the 6,8-disubstituted products. |
| 2. | The reaction of methyl trifluoropyruvate with 2,2,4-trimethyl-1,2-dihydroquinoline gave the product of C8-alkylation, accompanied by lactamization. |
| 3. | The oxidation of 6-(2-hyhdroxyhexafluoro-2-propyl)-2,2,4-trimethyl-1,2-dihydroquinoline by hydrogen peroxide in the presence of sodium tungstenate gave a stable nitroxyl radical. |
10.
L. G. Vorontsova V. M. Shitkin O. S. Chizhov I. M. Petrova I. E. Chlenov V. A. Tartakovskii 《Russian Chemical Bulletin》1976,25(4):790-794
| 1. | We have determined the confirmations and accurate geometrical parameters for the two isomers of 8-p-bromophenyl-6-cyano-2,9-dioxa-1-azabicyclo[4.3.0]nonane. |
| 2. | Replacement of the nitro group by the cyano group proceeds mainly with inversion of configuration at the center of substitution. |
11.
| 1. | Using seven independent methods it was found that the concentration of the active centers on the surface of-Al2O3, which are responsible for the dehydration, is (9±1)×1017 centers/m2. The catalytically active centers are identical with adsorption centers. |
| 2. | A method of calculating the stochiometry, concentration, and thermodynamics of the surface association reactions has been developed. |
| 3. | The first reaction step proceeds according to the associative bimolecular substitution mechanism, with the formation of an associative intermediate compound. The association enthalpy and entropy have been calculated. |
12.
| 1. | In contrast to the case of cyanoacetylene, the nucleophilic addition to methyl propiolate takes place with the preferential or exclusive formation of trans products, if steri cally hindered N-nucleophiles and N-, P-, S-nucleophiles with a weakened +M-effect of the central heteroatom are used. |
| 2. | For the qualitative evaluation of the stereochemical result of the nucleophilic addition reaction to activated acetylenes, it was proposed to use the R constant of the activating substituent. |
13.
N. F. Yudanov E. G. Boguslavskii I. I. Yakovlev S. P. Gabudar 《Russian Chemical Bulletin》1988,37(2):200-203
| 1. | A method has been developed for the intercalation of solid substances from solutions in organic solvents into graphite fluoride C2Fx. |
| 2. | Molecules of inserted paramagnetic copper complexes and nitroxyl radicals assume oriented positions between the structural layers in graphite fluoride. |
| 3. | The planes of molecules of bis-chelate Cu(II) complexes with acetylacetone, o-hydroxyquinoline, and phenylsalicylaldimine were determined to lie parallel to the C2Fx planes. |
| 4. | A method has also been suggested for the preparation of samples from C2Fx·yA compounds with a higher degree of texturizing (more nearly complete orientation) than can be achieved by pelletizing. |
14.
R. G. Gasanov I. I. Kandror M. Ya. Khorlina R. Kh. Freidlina 《Russian Chemical Bulletin》1976,25(8):1657-1660
| 1. | The 1,2-migration of chlorine in polyhalo-alkyl radicals of the RCH2CHCCl2X (X=H, F, CH3; R= CCl3, CHCl2). |
| 2. | 2-Methyl-2-nitroso-3-butanone is an effective trap for nonregrouping radicals, while 2-methyl-2-nitrosopropane is an equally effective trap for regrouping radicals of the RCH2CHClCClX type. |
15.
P. Ya. Bayushkin E. N. Gladyshev G. A. Razuvaev E. A. Emelina 《Russian Chemical Bulletin》1976,25(2):431-433
| 1. | The first stable compound with an O-Hg-Ge grouping was obtained by the reaction of 4,6-ditert-butyl-1,2-benzoquinone with bis(triisopropylgermyl)mercury. |
| 2. | A study was made of the photodecomposition of 1-triisopropylgermyloxy-2-triisopropylgermyl-mercuroxy-3,5-di-tert-butylbenzene, and also of its reaction with hydrochloric acid and ethylmercury chloride. |
16.
| 1. | Indium atoms have been obtained in aqueous solutions of univalent indium by pulse radiolysis. |
| 2. | In0 reacts with In+ to form the dimer In 2 + . |
| 3. | The optical characteristics of these particles, the rate constants for their formation and loss, as well as the oxidation-reduction potentials have been determined. |
17.
A. M. Moiseenkov V. A. Dragan A. V. Lozanova V. V. Veselovskii 《Russian Chemical Bulletin》1988,37(8):1603-1609
| 1. | Dimethyl, diphenyl, and tetramethylene sulfoxide hydrochlorides react with methylheptenyl, citronellyl, and geranyl acetates to give predominantly the allylic chlorination products. |
| 2. | These findings are preferably to be regarded as involving AdE reactions between the weakly electrophlic hydroxy and (or) chlorosulfonium cation and the trisubstituted C=C bond in these olefins at the key stage. |
| 3. | The addition of lithium perchlorate has been found to accelerate this reaction. |
| 4. | Sulfoxide hydrobromides are highly selective brominating agents for the terminal grouping in isopropenoid oligoolefins. |
18.
B. K. Nefedov N. S. Sergeeva T. V. Zueva E. M. Shutkina Ya. T. Eidus 《Russian Chemical Bulletin》1976,25(3):565-569
| 1. | Methanol, containing 10–20 mole % of CH3I, is carbonylated to methyl acetate in the presence of impregnated Eh-zeolite NaX catalyst at 230–250° and atmospheric pressure. |
| 2. | The specific (per gram of Rh) rate of methyl acetate formation is antibatic to the Rh content in the catalyst, it increases with increase in the methanol contact time, and shows little change in the range 230–250°. |
| 3. | The rate of forming the sole secondary product, namely dimethyl ether, decreases with increase in the amount of Rh and the methanol contact time. |
| 4. | CH2I is an astoichiometric component of the reaction. |
19.
G. A. Artamkina A. Yu. Mil'chenko I. P. Beletskaya O. A. Reutov 《Russian Chemical Bulletin》1988,37(12):2550-2556
| 1. | The kinetics of reactions of alkali metal salts of 9-carbomethoxy- and 9-cyanofluorene with para-nitrofluorobenzene and of Me3SnM with pentafluoropyridine have been studied. |
| 2. | In the case of carbanions the free anions are more reactive, while in the case of Me3SnM the corresponding tight (contact) ion pairs are more reactive. |
| 3. | The effect of the leaving group (on reactivity) was investigated using the reactions of pentafluorochlorobenzene with the K salts of 9-carbomethoxyfluorene and cyclopentadienylirondicarbonyl anions as examples. |
| 4. | The reaction mechanism has been shown to depend on the nature of the nucleophile. |
20.
| 1. | Rhodium complexes [RhCl(COD)]2, RhCl(PPh3)3, and RhCl3 immobilized on silica gel modified by aminophosphine groups catalyze the transfer of hydrogen from 2-propanol to cyclohexanone, styrene, and 2-cyclohexenone and the isomerization of allylbenzene in an argon atmosphere. |
| 2. | The reduction of cyclohexanone to cyclohexanol is promoted by alkali. The reaction rate is proportional to the amount of catalyst, 2-propanol concentration, and cyclohexanone. The reaction rate decreases at high ketone concentrations. |
| 3. | Styrene is reduced to ethylbenzene extremely slowly. Under these conditions, allylbenzene is not reduced, but rather undergoes isomerization with the predominant formation of trans-propenylbenzene. |
| 4. | The reduction of 2-cyclohexenone to cyclohexanol occurs by the initial reduction of the C=C bond and the subsequent reduction of the C=O group. |