Abstract: Novel composite ceramic materials include a boron nitride matrix and an amount of silicon components compatible therewith; such ceramic materials comprise a core volume having an external sheath layer on an outer face surface thereof, with the majority of said silicon values being distributed throughout the external layer.

Abstract: Process for the preparation of: ##STR1## by oxidative decarboxylation of an allyl .beta.-ketoester: ##STR2## in an organic solvent, in the presence of a palladium-based catalyst. The organic solvent selected from an amide, a nitrile, or a dinitrile.

Abstract: Crosslinked boron/nitrogen preceramic polymers are prepared by reacting (a) admixture of a trihalogenoborane A and a compound B containing at least one dihalogenated boron atom, with (b) an amino compound C containing at least one --NH.sub.2 group; the resulting polymers are facilely pyrolyzed into boron nitride ceramic materials.

Abstract: Marterials which are active in nonlinear optics, having a repeating unit of the following formula I: ##STR1## in which R.sub.1 and R.sub.2, are either identical or different, and denote a linear or branched methylenic chain, preferably containing from 2 to 6 carbon atoms; R.sub.3 is an aliphatic, aromatic or arylaliphatic hydrocarbon radical; R.sub.4 and R.sub.5, which are identical or different, denote a nitrogen atom or a CH radical, or alternatively R.sub.4 and R.sub.5 are both carbon with the R.sub.4 -R.sub.5 bond being a double or a triple bond; and Z.sub.1 and Z.sub.2, which are identical or different, denote an aromatic group wherein Z.sub.1 optionally contains one or more substituents R.sub.7 and wherein Z.sub.2 optionally contains one or more substituents R.sub.7 in addition to group A, each substituent R.sub.7 may be lower alkyl, halogen, amido, amino, sulfoxide, hydroxyl radical, alkoxy and trifluoromethyl; and A denotes an electron-acceptor group, with Z.sub.2 having one or more groups A.

Abstract: Organometallic boron/nitrogen polymers, precursors of boron nitride, include recurring structural units of the formulae (I) and (II): ##STR1## wherein X is N-R.sup.3, Y is NR.sup.1 R.sup.2 and Z is N-R, in which R, R.sup.1, R.sup.2 and R.sup.3, which may be identical or different, are each a hydrogen atom, an optionally substituted hydrocarbon radical, or an organosilyl or hydrogenoorganosilyl radical and are prepared by reacting (a) at least one cyclic compound (compound A) containing recurring structural units of the formula (1): ##STR2## wherein A is a halogen atom and R is a hydrogen atom, an optionally substituted hydrocarbon radical, or an organosilyl or hydrogenoorganosilyl radical, with (b) at least one compound including at least one boron atom to which two halogen atoms are directly bonded (compound B), and (c) at least one compound containing at least one NH.sub.2 group compound C); the resulting organometallic polymers are facilely pyrolyzed into boron nitride ceramic materials.

Abstract: Novel ceramic materials include a boron nitride matrix and an amount of silicon values, such ceramic materials comprising a core volume having an external sheath layer on an outer face surface thereof, with the majority of said silicon values being distributed throughout the external layer.

Abstract: Highly pure boron nitride ceramic material, devoid of silicon values and having low carbon content, is prepared by pyrolyzing, under an atmosphere of ammonia, the product of the reaction between (i) at least one B-trihalogeno-borazole having the formula: ##STR1## and (ii) at least one primary amine having the formula:H.sub.2 N--Rin which formulae X is a halogen atom and R is an optionally substituted hydrocarbon radical having from 1 to 6 carbon atoms.

Abstract: Boron/nitrogen preceramic polymers are prepared by reacting (a) the product of mass thermolysis of a compound of Formula (1): ##STR1## in which A is a halogen atom and R is a hydrogen atom, a hydrocarbon radical, or an organosilyl or hydrogenoorganosilyl radical, with (b) an amino compound containing at least one --NH.sub.2 group; the resulting polymers are facilely pyrolyzed into boron nitride ceramic materials.

Abstract: Novel nonlinearly optically active polyurethane polymers, well suited for electrooptical applications, have recurring structural units of the formula: ##STR1## in which m is a number greater than 5; R.sub.1 and R.sub.2, which may be identical or different, are each a saturated or unsaturated alkyl or aromatic radical; R.sub.3 is a linear aliphatic, or cyclic aromatic or arylaliphatic hydrocarbon radical; and Y is a group including a radical containing dislocated .pi. electrons and an electron acceptor group (A).

Abstract: Crosslinked boron/nitrogen preceramic polymers are prepared by reacting (a) admixture of a trihalogenoborane A and a compound B containing at least one dihalogenated boron atom, with (b) an amino compound C containing at least one --NH.sub.2 group; the resulting polymers are facilely pyrolyzed into boron nitride ceramic materials.

Abstract: Compounds of formula ##STR1## in which n denotes an integer from 1 to 10 and X and Y, which are identical or different, each denote an electron-attracting group, are made by reacting a halogenating agent with a compound of formula ##STR2## in which R, X and Y are as hereinbefore defined, anionized by a base.

Abstract: Compounds halogenated in the .alpha.-position to an electron-attracting group of formula ##STR1## in which X denotes a halogen atom, R denotes a hydrogen atom or a hydrocarbon radical or a radical --(CH.sub.2).sub.3 --COOR.sub.1 and Z denotes a radical --CHO, --COR.sub.2, --COOR.sub.3, --CONR.sub.4 R.sub.5, --CN, --SO.sub.2 R.sub.6, --NO.sub.2, --CO--(CH.sub.2)p--COO.sub.1 or --COO(CH.sub.2)p--COOR.sub.1 are made by a halogenating deacylation of a compound of formula ##STR2## in which R' denotes a hydrogen atom or a hydrocarbon radical, R" denotes a methyl radical and Z' denotes a radical --CHO, --COR.sub.2, --COOR.sub.3, --CONR.sub.4 R.sub.5, --CN, --SO.sub.2 R.sub.6 or --NO.sub.2 or R' and R" may form a radical --(CH.sub.2)-- or R' and R" may form a radical --CO--(CH.sub.2)p-- or --COO(CH.sub.2)p--, using an alkali metal alcoholate or an alkali or alkaline-earth metal carbonate and a halogenating agent.

Abstract: Unsaturated compounds of the formula: ##STR1## in which: Q denotes alkyloxycarbonyl, cyano or formyl, R.sub.1 denotes a saturated or unsaturated aliphatic radical, R.sub.2 denotes a hydrogen atom or an alkyl radical, R.sub.3 denotes a hydrogen atom or an aliphatic radical and R.sub.4 denotes a hydrogen atom or a saturated or unsaturated aliphatic radical which may be substituted, are useful as intermediates in the synthesis of vitamin E.

Abstract: Process for preparing chlorinated ethylenic derivatives of the formula ##STR1## in which R.sub.1 represents acetyl, formyl optionally in the form of an acetal, hydroxy optionally as an ether or ester, alkyloxycarbonyl, alkyl of 1 to 12 carbon atoms substituted by one or more acetyl, formyl optionally in the form of an acetal, hydroxy optionally in the form of an ether or ester, or alkyloxycarbonyl, alkenyl of 2 to 12 carbon atoms containing one or more double bonds optionally substituted by one or more of acetyl, formyl optionally in the form of an acetal, hydroxy optionally in the form of an ether or ester, or alkyloxycarbonyl, or R.sub.1 represents 3-sulpholenyl or a radical of formula ##STR2## in which R.sub.2 denotes a hydrogen or acetyl, by reacting chlorine in a nonpolar aprotic solvent with a compound of general formula ##STR3## in which R.sub.1 is defined as above. The products of formula I, some of which are new, are useful as intermediates in the synthesis of terpene products such as vitamin E.

Abstract: Unsaturated compounds of the formula: ##STR1## in which: Q denotes alkyloxycarbonyl, cyano or formyl, R.sub.1 denotes a saturated or unsaturated aliphatic radical, R.sub.2 denotes a hydrogen atom or an alkyl radical, R.sub.3 denotes a hydrogen atom or an aliphatic radical and R.sub.4 denotes a hydrogen atom or a saturated or unsaturated aliphatic radical which may be substituted, are useful as intermediates in the synthesis of vitamin E.

Abstract: Substituted phenols of formula ##STR1## in which R.sub.1 is in an ortho or para position relative to the phenol function and denotes ##STR2## R.sub.2 denotes an acyclic radical optionally substituted by alkyl, hydroxy, alkoxycarbonyl, cyano or formyl, or a phenyl or naphthyl radical, and R denotes hydrogen or 1 to 4 substituents chosen from halogen, OH optionally in the form of ether or ester, alkyl, NO.sub.2, CHO optionally in the form of acetal, CH.sub.3 CO--, C.sub.6 H.sub.5 CO--, NH.sub.2, alkylamino, dialkylamino or alkoxycarbonyl, it being understood that 2 symbols R may form with the phenyl nucleus a condensed aromatic ring, which comprises reacting a butadiene of formula ##STR3## with a phenol for formula ##STR4## in water in the presence of a rhodium-based catalyst, a water-soluble phosphine and optionally an inorganic or organic base. The products of formula (I) are intermediates for the synthesis of vitamin E, antioxidants, perfumes or insecticides.

Abstract: The new tetraene of formula: ##STR1## is useful particularly as an intermediate in the synthesis of, for example, hexahydropseudoionone, pseudoionone and vitamin A.It may be made by dehydrochlorinating 3-chloro-2-methyl-6-methylene-1,3,7-octadiene in the presence of a palladium catalyst and an inorganic base.