Abstract: Catalysts for facilitating cross-linking of liquid precursors into solid dielectric materials are disclosed. Initially, catalysts are protected, either by coordination with other compounds or by conversion to an ionic salt. Protection prevents catalysts from facilitating cross-linking unless activated. A catalyst is activated upon receiving an excitation, e.g. thermal excitation by heating. Upon receiving an excitation, protection of a catalyst dissociates, decomposes, becomes neutralized, or is otherwise transformed to allow the catalyst to facilitate cross-linking of the precursors into solid dielectric materials. Methods for fabricating dielectric materials using such protected catalysts as well as devices comprising the resulting materials are also described. Dielectric materials comprising cross-linked cyclic carbosilane units having a ring structure including C and Si may be formed in this manner.

Abstract: Selective reduction methods for halogenated carbosilanes and carbodisilanes are disclosed. More particularly, high yields of the desired carbosilanes and carbodisilanes are obtained by reduction of their halogenated counterparts using a reducing agent and tetrabutylphosphonium chloride (TBPC) as a catalyst.

Abstract: The present invention relates to a process for the production of perhalogenated hexasilane anion by reacting halogenated monosilane in the presence of organosubstituted ammonium and/or phosphonium halide at temperatures in a range from 100 to 120° C., wherein no solvent is used, and a process for the production of a cyclic silane compound of the formula Si6R12, by reacting [X]2[Si6Cl14] with AlR3 in at least one organic solvent, wherein R is chlorine or methyl and X, the same or different, is a counter-cation and is preferably selected from organosubstituted ammonium, organosubstituted phosphonium, alkali metal ions and [(PEDETA)(H2SiCl)]+.

Abstract: Provided is a method for efficiently producing alkoxysilanes that are useful as various functional chemicals. In order to produce alkoxysilanes efficiently, an ethoxy- or methoxysilane and an alcohol are caused to react using, as a catalyst, for instance an inorganic solid acid having a regular-pore and/or layered structure. Zeolites, montmorillonites or the like can be used as the inorganic solid acid. When a zeolite is used as the catalyst, the silica/alumina ratio of the zeolite ranges preferably from 5 to 1000. The reaction can be promoted through irradiation of microwaves.

Abstract: A process for preparing fexofenadine is described, which provides for the hydrolysis of 4-[4-[4-(hydroxydiphenylmethyl)-1-piperidyl]-1-oxobutyl]-?,?-dimethylbenzeneacetic acid-alkyl ester, in a mixture of water and optionally an organic solvent, in the presence of a base; the carboxylate salt of 4-[4-[4-(hydroxydiphenylmethyl)-1-piperidyl]-1-oxobutyl]-?,?-dimethylbenzeneacetic acid is thus obtained, which is then directly reduced as carboxylate in a basic environment with hydrogen in the presence of a suitable hydrogenation catalyst to give the carboxylate of fexofenadine, which is precipitated by neutralization of the solution.

Abstract: Alkyl chlorosilanes from the manufacture of dialkyldichlorosilanes are rearranged in continuous fashion to dialkyldichlorosilane by a rearrangement reaction in a moving bed reactor employing a solid alumina catalyst containing aluminum chloride, spent catalyst being continuously removed from the reactor.

Abstract: The invention provides highly resilient synthetic hydrogels, which can be prepared, for example, by using the efficient thiol-norbornene chemistry to cross-link hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) polymer chains. The simple hydrogel system with enhanced mechanical properties is useful in many applications, including in the biomedical field and in the design of protective and corrective wear.

Abstract: Production of polycrystalline silicon in substantially closed-loop processes and systems is disclosed. The processes and systems generally involve disproportionation of trichlorosilane to produce silane or dichlorosilane and thermal decomposition of silane or dichlorosilane to produce polycrystalline silicon.

Abstract: Discloses herein is a catalytic process for producing organohalosilane monomers from a high-boiling residue resulting from the Direct Reaction of an organohalide with silicon. The high-boiling residue contains more conventionally cleavable compounds than conventionally uncleavable compounds. The process includes heating the residue in the presence of a catalyst comprising (1) one or more heterocyclic amines and/or one or more heterocyclic ammonium halides, and (2) one or more quaternary Group 15 onium compounds.

Abstract: The invention pertains to a method of producing organohalohydrosilanes by treating a silicon metal with a halogen-containing compound, wherein the halogen-containing compound has a formula selected from RdSiX4-d (II) and RX (III), combining a catalyst and a promoter with the treated silicon metal, and contacting the combination with hydrogen gas and an organohalide. The invention also pertains to a method of producing organohalohydrosilanes by contacting an organohalide and hydrogen gas with a combination of silicon metal, a catalyst, a promoter and a hydrogen storage material. The invention also pertains to a method of producing organohalohydrosilanes by contacting an organohalide and hydrogen gas with a combination of a silicon metal, a catalyst, a promoter and a hydrogenation catalyst. The invention also pertains to a method of producing organohalohydrosilanes by contacting an organohalide and hydrogen gas with a reaction mass residue and optionally a hydrogenation catalyst.

Abstract: The object of the invention is a method for preparing silanes of the general formula (1) RaHbSiCl4?a?b (1), wherein mixtures of silanes of the general formulas (2) and (3) RcSiCl4?c (2), RdHeSiCl4?d?e, where R indicates an alkyl radical with 1 to 6 carbon atoms, a indicates the values 1, 2 or 3, b indicates the values 0 or 1, c indicates the values 1, 2, 3 or 4, d indicates the values 0, 1 or 2 and e indicates the values 0, 1 or 2, are reacted in the presence of an aluminum oxide catalyst comprising 1 to 10 parts by weight of aluminum chloride and 0.5 to 10 parts by weight of a metal oxide selected from magnesium oxide, copper oxide, zinc oxide and mixtures thereof to 100 parts by weight of aluminum oxide.

Abstract: The present invention relates to a method for producing monosilane and tetraalkoxysilane comprising subjecting alkoxysilane represented by formula (1) HnSi(OR)4?n??(1) wherein R represents alkyl group having 1 to 6 carbon atoms and n represents an integer of from 1 to 3, to disproportionation reaction in a gaseous phase in the presence of an inorganic phosphate or a catalyst having a specific chemical structure based on a heteropolyacid salt structure. In the production method of the present invention, separation from the solvent can be carried out easily, the reaction proceeds quickly and the conversion rate of the starting materials is high.

Abstract: Provided is an organic chlorohydrosilane, a useful starting material for preparing silicon polymers and a method for preparing the same. More particularly, the present invention enables the synthesis of various novel organic chlorohydrosilanes in high yield by an exchange reaction between an Si—H bond of a chlorosilane which can be obtained in an inexpensive and easy manner and an Si—Cl bond of an another organic chlorosilane using a quaternary organic phosphonium salt compound as a catalyst. Since the catalyst can be recovered after its use and reused, the present invention is very economical and thus effective for mass-producing silicon raw materials.

Abstract: The object of the invention is a method for preparing silanes of the general formula (1) RaHbSiCl4?a?b (1), wherein mixtures of silanes of the general formulas (2) and (3) RcSiCl4?c (2), RdHeSiCl4?d?e, where R indicates an alkyl radical with 1 to 6 carbon atoms, a indicates the values 1, 2 or 3, b indicates the values 0 or 1, c indicates the values 1, 2, 3 or 4, d indicates the values 0, 1 or 2 and e indicates the values 0, 1 or 2, are reacted in the presence of an aluminum oxide catalyst comprising 1 to 10 parts by weight of aluminum chloride and 0.5 to 10 parts by weight of a metal oxide selected from magnesium oxide, copper oxide, zinc oxide and mixtures thereof to 100 parts by weight of aluminum oxide.

Abstract: Silanes of the general formula (1) RaSiHbX4-b-a??(1) are prepared by disproportionating at least one more highly chlorinated silane in the presence of a homogeneous catalyst in an apparatus with at least one reactive distillation column and at least one additional reactor selected from among prereactors and side reactors, where R is an alkyl, aryl, alkaryl or haloalkyl radical, X is a halogen atom, a is 0 or 1, and b is 2, 3 or 4.

Abstract: The disclosure herein relates to organofunctional silanes and mixtures of organofunctional silanes possessing mercaptan and hydrocarbyl and/or heterocarbyl functionality. These silanes reduce or eliminate the generation of volatile organic compounds (VOC's) during use, aid in the processing of filled elastomeric materials and enhance the end-use properties of the filled elastomer. The present disclosure relates to a rubber composition and article comprising these silanes.

Abstract: The invention relates to a process for the direct synthesis of methylchlorosilanes by reaction of chloromethane with a contact composition comprising silicon and copper catalyst, wherein the concentration of oxygen in the chloromethane used is reduced by mixing a) chloromethane which contains oxygen, and b) chloromethane which contains a gaseous boron compound.

Abstract: Organylhydrogensilanes are prepared by means of a comproportionation reaction according to the equation Z RaSiCl4?a+SiHbCl4?b?Z RaSiHCl3?a+SiHb?yCl4?b+y, in the presence of a catalyst which contains at least one completely organically substituted ammonium or phosphonium unit, where R is an optionally halogen-substituted alkyl, aryl, or alkaryl radical, a is 1, 2 or 3, y and Z are 1, 2, 3 or 4 and b is 2, 3 or 4.

Abstract: Silanes of the general formula (1) RaSiHbX4-b-a ??(1) are prepared by disproportionating at least one more highly chlorinated silane in the presence of a homogeneous catalyst in an apparatus with at least one reactive distillation column and at least one additional reactor selected from among prereactors and side reactors, where R is an alkyl, aryl, alkaryl or haloalkyl radical, X is a halogen atom, a is 0 or 1, and b is 2, 3 or 4.

Abstract: The present invention provides a novel method for the preparation of diorganosilanes by disproportionation of a hydridosiloxanes comprising at least one terminal SiH group and at least one siloxane bond in the presence of Lewis acid catalysts. The reaction is both selective and occurs under mild conditions. The triaryl borane, tris(petafluorophenyl)borane, is especially suited for use as a catalyst in the reaction. Organic catalysts such as tris(pentafluorophenyl)borane are typically preferred owing to their greater solubility and stability in the reaction mixture, relative to inorganic Lewis acid catalysts. The product, diorganosilane may be isolated from the product mixture by conventional techniques such as distillation.

Abstract: By reacting two types of organosiloxane compounds in the presence of an alkaline compound and under conditions that do not substantially promote equilibration reaction, a linear organosiloxane polymer having a single peak molecular weight distribution is simply and economically produced with minimized formation of cyclics.

Abstract: Three processes for the manufacture of polyhedral oligomeric silsesquioxanes (POSS) which utilize the action of bases that are capable of either attacking silicon or any compound that can react with a protic solvent (e.g. ROH, H2O etc.) and generate hydroxide [OH]?, alkoxide [RO]??, etc. The first process utilizes such bases to effectively redistribute the silicon-oxygen frameworks in polymeric silsesquioxanes [RSiO1.5]28 where ?=1-1,000,000 or higher into POSS nanostructures of formulas [(RSiO1.5)n?#, homoleptic, [(RXSiO1.5)n]?#, functionalized homoleptic, [(RSiO1.5)m(R?SiO1.5)n]?#, heteroleptic, and {(RSiO1.5)m(RXSiO1.0)n}?#, functionalized heteroleptic nanostructures. The second process utilizes base to aid in the formation of POSS nanostructures of formulas [(RSiO1.5)n]?# homoleptic and [(RSiO1.5)m(R?SiO1.5)n]?# heteroleptic and [(RSiO1.5)m(RXSiO1.

Abstract: A process for the generation of energy by the combustion of silicon compounds having the bonds Si—C, Si—O, Si—Si and/or Si—H is described. Such compounds are appropriate energy carriers as alternative with respect to hydrocarbons.

Abstract: A diorganodichlorosilane is prepared by subjecting organochlorosilanes to disproportionation reaction in the co-presence of a SiH group-containing compound and in the presence of a primary catalyst of AlCl3 or AlBr3 and a co-catalyst of Mg, Al, Ca, Ti, Fe, Ni, Cu, Zn or Sn or a compound thereof. The invention enables disproportionation reaction of organochlorosilanes under atmospheric pressure and at a low temperature at which no substantial sublimation of AlCl3 or the like occurs, thus allowing the reaction equipment to be simple and improving the safety of reaction.

Abstract: A diorganodichlorosilane is prepared by subjecting organochlorosilanes to disproportionation reaction in the co-presence of a SiH group-containing compound and in the presence of a primary catalyst of AlCl3 or AlBr3 and a co-catalyst of Mg, Al, Ca, Ti, Fe, Ni, Cu, Zn or Sn or a compound thereof. The invention enables disproportionation reaction of organochlorosilanes under atmospheric pressure and at a low temperature at which no substantial sublimation of AlCl3 or the like occurs, thus allowing the reaction equipment to be simple and improving the safety of reaction.

Abstract: Silanes of the formula

Abstract: A process for preparing linear organohydrogensiloxanes. The process comprises contacting an organohydrogendichlorosilane in the presence of trimethylchlorosilane with water to form an M-stopped hydrolyzate. The hydrolyzate is optionally preheated prior to being contacted with an acidic rearrangement catalyst to effect formation of linear organohydrogensiloxanes. The linear organohydrogensiloxanes are separated from cyclic organohydrogensiloxanes and recovered. The cyclic organohydrogensiloxanes may then be recycled to the process for further contact with the acidic rearrangement catalyst for maximum overall conversion rate.

Abstract: A process is disclosed for the continuous transesterification of alkoxysilanes wherein an alkoxysilane is transformed to a different alkoxysilane in the presence of a catalyst and at least one alcohol that provides the different alkoxy group.

Abstract: The invention relates to a process for preparing alkylchlorosilanes from the liquid constituents of the residues from the direct synthesis of alkylchlorosilanes which have a boiling point of above 70° C. at 1013 hPa and comprise disilanes, in which the residues are heated with hydrogen chloride and silicon at temperatures of at least 300° C., with at least 10% by weight of trichlorosilane and/or tetrachlorosilane, based on the weight of the alkylchlorosilanes formed, being formed at the same time.

Abstract: The invention concerns a method for obtaining alkylmonohydrogenohalogenosilanes (AHHS), for example Me2HSiCl.Said AHHS are prepared by redistribution from MeHSiCl2 and Me3HSiCl in the presence of a catalyst such as AlCl3, which can start a parasitic disproportionation which affects the AHHS produced. In order to avoid this, the method consists in using an inhibitor which neutralizes AlCl3 after redistribution, The problem which still prevails and on which the present invention is based is related to the fact that during distillation, which aims at separating the required AHHS, the latter are again subjected to the parasitic disproportionation.

Abstract: A method for preparing a silicone emulsion, more particularly a method for preparing a silicone emulsion with a low cyclic siloxane level and particle size control.

Abstract: A redistribution reaction between organohydrochlorosilanes and optionally chlorinated organosilanes is run in the presence of a catalyst in the solid state which comprises an alumina with an alkali metal or alkaline earth metal content expressed in ppm of the corresponding oxides of less than or equal to 500 ppm.

Abstract: Improved method for obtaining organosilanes comprising: a redistribution reaction between a chlorinated organohydrogenosilane and an organo-substituted and optionally chlorinated silane, the distribution reaction taking place in the presence of a sufficient amount of a catalyst consisting of a Lewis acid of formula (3) M(X).sub.d in which: M represents a metal selected among Ti, Fe, Cu, Ag, Zn, Cd, Hg, Al, Ga, In, B, Sn, Pb, Sb, and Bi; X represents a halogen atom; d represents the valency of metal M; and separation by distillation of the chlorinated organohydrogenosilane produced by redistribution; the said method being characterized in that, after redistribution, a redistribution catalyst inhibiting compound is used. This catalyst is selected among the fluid polyorganosiloxanes (POS) having a viscosity at 25.degree. C. not exceeding 5000 mPa.cndot.

Abstract: An improved redistribution reaction for the preparation of organosilanes wherein a silane or silicone resin is added after the reaction to inhibit the catalyst.

Abstract: Polyorganosiloxazane is provided which is capable of being converted into a ceramic material having low dielectric constant. The polymer according to the present invention is characterized by comprising the main repeating units of --(RSiN.sub.3)--, --(RSiN.sub.2 O)--, --(RSiNO.sub.2)-- and --(RSiO.sub.3)--, wherein, R represents an alkyl, alkenyl, cycloalkyl, aryl, alkylamino or alkylsilyl group, and by having a number-average molecular weight ranging from 300 to 100,000. The polyorganosiloxazane of the present invention has superior thermal resistance, and a ceramic material obtainable by firing the same at a predetermined temperature shows very low specific dielectric constant of 2.7 or less, making it useful particularly as a material in electronics.

Abstract: Higher alkoxysilanes are prepared efficiently and in high yield by transesterification of lower C.sub.1-4 alkoxysilanes with C.sub.6-38 higher alcohols at reduced pressure with continuous removal of lower alcohol. The products have little or no lower alkoxy content, and are free of coloring impurities.

Abstract: An exchange reaction of hydroxyl and alkoxysilane is used as a polymerization avenue yielding hyperbranched polymers. A monomer containing hydroxy alcohol functionality and alkoxy functionality attached to a silicon atom in the monomer is employed, and a simple exchange reaction with driving off of alcohol by-product leads to the desired hyperbranched polymerization and materials.

Abstract: A method for manufacturing a siloxane compound described by formula R.sup.1.sub.m Si{OSi(CH.sub.3).sub.2 H}.sub.(4-m) comprising reacting a silane compound or condensation product of a silane compound described by formula R.sup.1.sub.m Si(OR.sup.2).sub.(4-m), where R.sup.1 is selected from the group consisting of hydrogen and substituted or unsubstituted monovalent hydrocarbon groups, R.sup.2 is hydrogen, alkyl groups and alkoxyalkyl groups, and m is an integer from 0 to 3, with 1,1,3,3-tetramethyldisiloxane in an aqueous solution of an acid in which the acid concentration is 1.0 wt % or less, and the molar ratio of the aqueous solution to the 1,1,3,3-tetramethyldisiloxane is in the range of 0.5 to 1.5. The method is particularly useful for manufacturing siloxane compounds having dimethylhydrodosiloxy groups.

Abstract: A process for preparing organosilicon compounds having Si-bonded hydrogen atoms comprises,in a first step,reacting silanes of the general formula R.sup.1 R.sub.a SiX.sub.3-a, where R. is a monovalent hydrocarbon radical free from aliphatic multiple bonds, R.sup.1 is a monovalent terminal unsaturated hydrocarbon radical, X is a halogen atom or a radical of the formula --OR.sup.2, and a is 0 or 1; with organosilicon compounds having at least two Si-bonded hydrogen atoms per molecule; in the presence of catalysts which promote the addition of Si-bonded hydrogen to an aliphatic multiple bond; and removing excess silanes by distillation, where the ratio employed of aliphatic double bond in the silane to Si-bonded hydrogen in the organosilicon compound is from 1.0 to 2.0; andin a second step,reacting the resultant compounds having hydrolyzable groups with silanes of the general formula H.sub.b R.sub.3-b SiZ or siloxanes of the general formula H.sub.b R.sub.3-b SiOSiR.sub.3-b H.sub.

Abstract: The present invention relates to radiation curable silicone vinyl ethers and methods for preparing silicone vinyl ethers. More particularly, the present invention relates compositions containing vinyl ether functional silicones and to the preparation and use of silicone vinyl ethers which are curable by addition of photocleavable acids and exposure to ultraviolet or electron beam radiation.

Abstract: Provided is a process for the preparation of polyorganosiloxanes containing unsaturated functions. A polyorganohydrogenosiloxane (A) containing at least 0.1 mol % of hydrogen atoms linked directly to the silicon is reacted with at least a stoichiometric amount of a hydrocarbon compound (B) having at least one ethylenic or acetylenic unsaturation, in the presence of a catalytically effective amount of a dehydrogenative condensation catalyst comprising a metal complex of formula (I): L.sub.n MR.sub.x Y.sub.y. M represents a metal chosen from titanium, zirconium and hafnium; the symbols L are the same or different and represent a hydrocarbon ligand of the metal M, the said ligand donating from 3 to 8 .pi.-electrons to the valence shell of the said metal; n is an integer ranging from 0 to 3; the symbols R are the same or different and represent a hydrocarbon or organosilicon ligand of the metal M, the ligand being a .sigma.

Abstract: The present invention relates to a process for the preparation of organo silicon disulfide compounds. The process involves reacting a mercaptoalkoxysilane with a dithiobis(benzothiazole) compound.

Abstract: The invention relates to a process for preparing organosilanes which contain at least one Si-bonded hydrogen in the presence of a phosphonium catalyst, the phosphonium catalyst itself and also a process for its preparation.

Abstract: The present invention relates to a process for the preparation of organo silicon disulfide compounds. The process involves reacting a mercaptoalkoxysilane with a sulfenamide compound.

Abstract: Alkylhydrogenchlorosilanes of formula I:R.sub.x HSiCl.sub.y (I)wherein R are identical or different alkyl radicals, x is 1 or 2 and y is 1 or 2 and the sum of x and y is equal to 3, are prepared by comproportionating alkylchlorosilanes of formula II:R.sub.a SiCl.sub.n (II)wherein R denotes identical or different alkyl radicals, a is 1 or 2 and n is 2 or 3 and the sum of a and n is equal to 4 with hydrogenchlorosilanes of formula III:R.sub.b H.sub.c SiCl.sub.4-b-c (III)wherein R denotes identical or different alkyl radicals, b is 0, 1, 2 or 3 and c is 1, 2, 3 or 4 and the sum of b and c is equal to or smaller than 4, in the presence of a catalyst saturated with a hydrogen halide.

Abstract: Disclosed is a process for preparing a polyorganosilane which comprises subjecting a disilane compound having at least two substituted or unsubstituted hydrocarbyloxy groups in one molecule to disproportionation reaction in the presence of a catalyst comprising a reaction product of an organic alkali metal compound represented by the formula (I):RM (I)wherein R represents a substituted or unsubstituted monovalent hydrocarbon group; and M represents an alkali metal,represented by the formula (III):MR.sup.3.sub.p M (III)wherein R.sup.3 represents a saturated or unsaturated chain or cyclic divalent hydrocarbon group or a divalent heterocyclic group, two or more R.sup.3 s may be the same or different and an ether oxygen atom may exist between two or more R.sup.3 s; p represents an integer of 1 or more; and M represents an alkali metal atom,and at least one of a disilane compound and a silane compound both of which have a substituted or unsubstituted hydrocarbyloxy group(s).

Abstract: The invention relates to a process for preparing alkyl- or aryldichlorosilanes by comproportionation of alkyl- or aryltrichlorosilanes with at least one silane containing Si-bonded methyl groups, hydrogen and/or chlorine atoms in the presence of a catalyst, and also a catalyst.

Abstract: The invention relates to a series of novel silicone compounds which contain fatty alkyl groups. This class of compounds provides unique solubility in many organic softeners, and increases the effectiveness of the softening of fatty quats. These materials are applied to fibers including textile fibers and hair and skin. The compounds of the present invention contain which contain a fatty substituted quaternary group, a silicone group and a reactive silanol groups. The presence of the positive charge on the nitrogen results in substantivity to many substrates, the presence of a silicone portion results in compatability in silicone fluids and the presence of the fatty tail on the molecule results in fatty solubility. The resulting material is surface active and will allow for the incorporation of silicone into a fatty system or of a fatty quat in a silicone system.

Abstract: Hydrolysis of an alkoxysiloxane of the formula: R.sup.1.sub.a (R.sup.2 O).sub.b SiO.sub.(4-a-b)/2 wherein R.sup.1 is a monovalent hydrocarbon group, R.sup.2 is an alkyl group having 1 to 4 carbon atoms, letter a=0 to 2.2, b=0.2 to 3, 2.ltoreq.a+b.ltoreq.3, and the number of silicon atoms in a molecule is 2 to 5, is effected in the presence of a cation exchange resin by adding water therereto in an amount of 1 to 10 mol per mol of the alkoxy group in the alkoxysiloxane and agitating the mixture. Low molecular weight, linear organosiloxanes having a silanol terminal group including dimer diol and trimer diol are produced in high yields.

Abstract: There is provided a method of producing an organopolysiloxane with a low polymerization degree in a high yield, comprising a step of allowing a monochlorosilane represented by the following general formula (I) and hexamethylcyclotrisiloxane to undergo ring-opening reaction in the presence of a quaternary ammonium salt represented by the following general formula (II) and a step of hydrolyzing the reaction product: ##STR1## wherein R groups are the same or different, and each group represents an alkyl group containing 1 to 18 carbon atoms, an aryl group or a hydrogen atom;R.sup.1.sub.4 N.sup.+ X.sup.31 (II)wherein R.sup.1 groups are the same or different, each group representing an alkyl group containing 1 to 18 carbon atone, and X- represents an anion.