Etudes photochimiques—XIII : Reactions de photoaddition du benzo[b]thiophene avec des amines et avec le pyrrole

The photochemical behavior of benzo[b]thiophene is different from that of thiophene. The former does not undergo photoisomerization and is not converted into an indole when irradiated in the presence of a primary amine; its photochemical behavior resembles that of naphthalene. Thus photoexcited benzo[b]thiophene gives adducts with primary amines (1(H)), secondary amines (2), and pyrrole (3(H)): an exciplex is an intermediate. The existence of the exciplex is supported by the formation of aldehyde 7 when benzo[b]thiophene is irradiated in aqueous propylamine, the finding that photoexcited benzo[b]thiophene does not react with an alcohol and that photoexcited indole benzo[b]furan, 2-methylbenzo[b]thiophene, and 3-methylbenzo[b]thiophene do not react with propylamine or with piperidine. The results are interpreted in terms of spin densities calculated for the anion radicals of the compounds under study.     

Analyse viscosimetrique des telomeres de l'acrylate d'ethyle et du chlorure de vinyle avec le tetrachlorure de carbone et le trichloroacetate de methyle

Telomers of ethylacrylate and vinylchloride with carbon tetrachloride or methyltrichloroacetate have been prepared by redox catalysis. They have the expected viscometric behaviour which depends upon the nature of the telogen. Thus viscometry can be used for determination of average molecular weight for such compounds.     

Influence des associations moleculaires sur la copolymerisation de l'acide acrylique avec l'acide methacrylique et avec l'acrylate de methyle

The copolymerization of acrylic acid with methacrylic acid in bulk is investigated at 40 and 60°. It is confirmed that a “matrix effect” occurs only for high contents of acrylic acid. The critical concentration beyond which the matrix effect disappears is shifted towards lower acrylic acid contents for higher temperatures. The copolymer composition is independent of temperature. The copolymerization of acrylic acid with methyl acrylate is investigated in a mixture which determines an “exaltation of the matrix effect” in the homopolymerization of acrylic acid (molar fractions: m_Monomers = 0.34; m_n-Hexane = 0.52; m_Methanol = 0.14). The resulting copolymers are found to contain a much larger fraction of acrylic acid residues than the copolymers formed in bulk or in toluene or DMF solutions.     

Reactions de l'hexafluorure de molybdene avec les aldehydes et les cetones fonctionnels

The substituents F, Cl, Br, CN, NO₂, COOR, CONR₂, P(O)R₂ do not interfere with the reaction of MoF₆ with aromatic aldehydes and ketones yielding gem-difluoro compounds, but OH, NH, OR, NR₂, CC, react preferentially with MoF₆ and prevent the reaction at CO. Yields of gem-difluoro compounds are enhanced with electron-attracting substituents on the carbonyl derivative, and are lowered when the CO group is sterically hindered. The hydrolytic stability of the RCF₂R′ compounds vary widely with the nature of R and R′. Some reactions on R and R′ leave the CF₂ group unaffected. Thus a number of new CF₂ compounds are prepared including α,α-difluoroalkyl substituted benzyl alcohol32 benzylamines34, 36 benzaldehyde27, benzoic acids24, 28, 31, 35.¹H and¹⁹F NMR data are given for all the new derivatives. The mechanism of the conversion is tentatively postulated.     

Reactions de l'acide perchlorique avec le phenylacetylene en solvant acide acetique anhydre

Perchloric acid in acetic acid reacts with phenylacetylene to give acetophenone, α-chloroacetophenone, α,α'-dichloroacetophenone, α-acetoxy α'chloroacetophenone, dichloro-styrène and chlorophenylacetylene. Kinetics of these reactions have been established.     

Reactions de wittig,wittig-horner et knoevenagel par activation anionique avec l'alumine ou le fluorure de potassium depose sur l'alumine,sans solvant

Wittig, Wittig-Horner and Knoevenagel reactions are achieved in the presence of alumina or potassium fluoride supported on alumina, without organic solvent. The presence of a small amount of water increases the rate of the Wittig and Wittig-Horner reactions. The reaction of the diethyl cyanomethylphosphonate with an aldehyde in the presence of dry alumina is oriented towards the Knoevenagel reaction.     

Copolymerization de l'acenaphtylene avec le n-vinylcarbazole

The copolymerization of acenaphthylene (ANA) with N-vinylcarbazole (NVC) was investigated at 60° in the melt with 1% AIBN and in benzene solution at 20° with gamma ray initiation. In the melt at 60°, the polymerization rate gradually decreases with the amount of NVC in the mixture. The following reactivity ratios were determined: r_NVC = 0.12; r_ANA = 7.0. The copolymers have a fairly narrow distribution of compositions but contain small amounts of poly NVC. Gamma ray initiation at 20° gives rise to the free radical copolymer together with significant amounts of poly NVC which results from a cationic mechanism. In addition, acenaphthylene cyclodimerizes in the process.     

Reaction de l'acetylene dicarboxylate d'ethyle avec l'oxo-6 (2H) cyclohepta (c) pyrrole ; mecanismes de formation des adduits

The cycloaddition reactions of 6-oxo (2H) cyclohepta (c) pyrroles $\text{4a, b and c}$ with diethyl acetylene dicarboxylate an electron-deficient dienophile of relatively low LUMO energy level, afford the 1:2 adducts $\text{5a, b}{}_1\text{-b}{}_2\text{and c}$ respectively The kinetics of the reactions, investigated By ¹H NMR spectroscopy, have allowed to precise the mechanism of the addition In particular, new-intermediates, 1:2' adducts $\text{6b and c}$ have been observed and isolated for the compound $\text{6c}$.     

Greffage radiochimique de l'acrylonitrile sur le poly(methacrylate de methyle)

The radiation-induced polymerization of acrylonitrile with dissolved PMMA exhibits kinetics similar to those found with the pure monomer. The addition of PMMA to the monomer at first leads to an increase in polymerization rate; a maximum in rate is observed for 60 per cent acrylonitrile in the mixture. The unreacted PMMA was quantitatively extracted by toluene from the reaction mixture. In contrast, polyacrylonitrile could not be separated from the graft copolymer by fractional precipitation, presumably due to association of the graft copolymer with the precipitated homopolymer. The free radical yield of PMMA “G_R effective” derived from these results was found to be 8 to 10 in mixtures containing small amounts of monomer. It rapidly decreased as the monomer concentration increased.The solubilities of the graft copolymers were characterized by the precipitation γ determined for several precipitants in DMF solutions. A maximum in solubility was found for copolymers containing 25 to 35 per cent acrylonitrile in DMF-alcohol mixtures. The glass transition temperatures (T_g) of the graft copolymers were measured using a penetrometer. T_g increased with the MMA content in the copolymer. A small minimum of T_g appeared to exist for copolymers containing 90 per cent acrylonitrile.     

Dosage de l'hydrogene,de l'azote et de l'oxygene dans le monocarbure d'uranium

A method is described for the determination of hydrogen, oxygen and nitrogen in uranium monocarbide. Hydrogen and oxygen are determined by the classical or modified “Platinum flux” method at 2000° with a coefficient of variation of 10%. Nitrogen is determined at 2000° by the modification of the “Platinum flux” technique. The results obtained are in agreement with those found by Kjeldahl analysis. The coefficient of variation is about 10%. A procedure for the simultaneous determination of the 3 gases is given.     

Sur l'acylation et l'alkylation de l'amino-4 pyrazolo [3,4-d] pyrimidine

New derivatives of 4-amino [3,4-d] pyrazolo pyrimidine have been prepared. Mono, di- and tri-substitution products are characterised by unequivocal synthesis. Several compounds are being tested for possible carcinostatic activity.     

Spectres RMN haute resolution des homopolymeres et copolymeres de l'acrylate de glycidyle avec le chlorure de vinyle

The HR-NMR spectra of the glycidyl acrylate homopolymer and (glycidyl acrylate-vinyl chloride) copolymers are described. The assignment of the different resonance groups allows quantitative determination of the compositions of the copolymers.     

Spectrometrie de masse d'heterocycles selenies. IV—comportement de quelques benzo[b]selenophenes 2,3-disubstitutes

The fragmentation of eighteen 2,3-disubstituted benzo[b]selenophenes under electron-impact have been studied. The influence of the substituents on the behaviour of heterocyclic nucleus and the degradation of the sidechains has been examined.     

Polymerisation cationique de l'indene amorcee par le tetrachlorure de titane-I Influence des impuretes du solvant,le chlorure de methylene,et effets cocatalytiques de l'eau et de l'acide chlorhydrique

The polymerization of the system indene-titanium tetrachloride-methylene chloride gave irreproducible kinetics which have been attributed to variable concentrations of impurities in the solvent. Incomplete yields sometimes observed at ?70° are also caused by impurities, but introduction of water and hydrochloric acid then gives complete yields. A new method of solvent purification has been used giving reproducible yields and rates. In such cases, monomer consumption at ?70° follows the rate law log [M]_o/[M] = kt.     

Etude cinetique de la copolymerisation alternee de l'indene et du methacrylate de methyle en presence de sesquichlorure d'ethylaluminium

The copolymerization of indene with methyl methacrylate (MAM) initiated by u.v. irradiation, in the presence of ethylaluminium sesquichloride (SCEA) as a complexing agent, yields alternating copolymers when [Indene] ≥ [MAM] ≥ [SCEA]. Values of $\text{M}$_n of the copolymers range from 32,000 to 900,000, depending on the concentrations of the reagents, reaction temperature and intensity of u.v. light. The kinetics can be explained simply by assuming a statistical copolymerization of indene with a MAM-SCEA binary complex, but intervention of a ternary complex SCEA-MAM-indene cannot be discarded. At high MAM concentrations, the free MAM becomes involved in the copolymerization.