1–3 Cycloaddition of 1,3-diphenyl-2-azallyllithium with arylallenes affords a general synthetic method for arylmethylenepyrrolidines, a new class of five-membered-heterocycles. 相似文献
We have employed the criteria defined by the CHETAH (ASTM) program to predict the lower and the upper flammability limits of various organic compounds. The results obtained for molecules containing carbon, hydrogen, oxygen and nitrogen are, in most cases, in good agreement with experimental values. The difficulties encountered when the molecule contains a heteroatom can be overcome by knowledge of the stoichiometric conditions of the combustion reactions. 相似文献
Heating αα′-tetrasubstituted ethers with sodium amide at 225–300° leads to smooth cleavage of one of the α-substituents, which is reduced in the process; the Intermediacy of an alkoxide ion is postulated, and a high yield cleavage of a tertiary alkoxide is indeed observed. 相似文献
Trimethylchlorosilane reacts with organotin imines or enamines leading mainly (or only) to the corresponding silicon enamine. In contrast, the silylation of lithium or magnesium iminates gives only the isomeric imine when the nitrogen is hindered by bulky groups (i-Pr, t-Bu).The study of the NSi ? CSi equilibration shows clearly that in both cases the isomer obtained is the kinetic product of each reaction.These results show that a proper choice of both the metal associated with the iminate and of the iminate itself allows the formation of each isomer in a pure state. 相似文献
The role of platinum and of some mineral oxides in improving the thermal stability of a silicone rubber has been studied by temperature-programmed thermogravimetric analysis and by isothermal pyrolysis. Platinum has no significant influence on the scission of side chains. It limits the rupture of the polymer backbone by preventing the formation of a transition complex involved in silicone degradation. Mineral oxides combine with certain products of the thermal decomposition of the polymer. 相似文献
Several methods of analysis for tin-samarium alloys are studied: chemical analysis, X-ray fluorescence and arc spectrography. Their characteristics and the results obtained are compared. The chemical methods are most precise but are insensitive and tedious. X-Ray fluorescence is suitable for routine work and for control of alloy homogeneity. Arc spectrography is by far the most sensitive method The methods can be applied to alloys of other rare earths with tin. 相似文献
The structure of sarothamnoside (genistein 7,4′-di-O-[4-O-β-D-glucopyranosyl-β-D-apiofuranoside]), a new isoflavone glycoside from and , patens, has been established by spectral analysis, mainly 13C NMR. 相似文献
The reaction of organozinc compounds RCHCHCH2ZnBr with ethyl chloroformate gives β-ethylenic esters CH2CHCH(R)COOC2H5 in good yields; these esters are readily converted to the corresponding α-ethylenic esters on treatment with piperidine. 相似文献
Aminoalkylphosphonic acids are prepared via amino group protection by nitrogen-phosphorus (P-N) bond formation. Phosphorylation of β or γ-bromoalkylamines with chlorophosphates followed by reaction of the resulting haloalkylphosphoramidates with triethylphosphite (Arbuzov reaction) to give a phosphoramidate-phos-phonate intermediate which can be alkylated with various reagents. Removal of the phosphoryl residue may be brought about by treatment with aqueous hydrogen chloride. Improvements in the isolation of the amino-phosphonic acids are described. 相似文献
The behavior of metallated imines and hydrazones toward α,β-unsaturated ketones was studied, using different reaction times and temperatures. Dissociation of the functional group (imine or hydrazone) in the adducts and regioselectivity in their condensation reactions are discussed. The first example of reversible addition to the carbonyl group of an enone is demonstrated for the reaction between trans chalcone and 相似文献
Tetraallytin reacts readily with non activated ketones and exothermically with aldehydes contrary to other allylic organotins such as allytributyltin. Homoallylic alcohols are obtained after acidolysis of the adducts. Upon extended heating, allylic organotins and epoxides form products which correspond to additon products of isomeric carbonyl compounds. However, starting from cis- and trans-1-phenyl-1,2-epoxypropanes, direct regiospecific but non-stereospecific ring opening is observed with poor yields. 相似文献