Abstract: The present invention is directed to polyimide systems which simultaneously offer low toxicity, a high glass transition temperature, excellent thermal oxidative stability, and desirable processing characteristics. These various polyimide systems include mixtures of monomeric reactants, polyimide-precursor reaction products, polyimides, and polyimide-containing articles. In one aspect of the invention, the mixture of monomeric reactants includes at least one dia-nhydride or a derivative thereof, and at least one diamine. The diamine may be 4,4′-[1,4-phenylene-bis(1-methylethylidene)]bisaniline, 4,4′-[1,3-phenylene-bis(1-methylethylidene)]bisaniline, and/or a derivative thereof. The diamine also may include a phenylenediamine, 2,2-bis[4-(4-aminophenoxyl)phenyl]propane, 4,4′(1,4-phenylene-bismethylene)bisaniline, and/or a derivative thereof. In addition, the mixture may include a reactive end-capping agent and/or a non-reactive end-capping agent.

Abstract: A process for preparing radiation-curable, urethane-functional prepolymers by reacting an isocyanate-functional component A with an OH-containing component B, wherein either component A embraces two different isocyanate compounds A1 or one isocyanate compound A1 and at least one isocyanate compound A2 or component B embraces at least two different compounds B1. Also, the prepolymers obtainable by the process and the radiation-curable formulations comprising them. Furthermore, the use of the radiation-curable formulations for coating substrates, a method of coating substrates, and the coated substrates themselves.

Abstract: The invention relates to a photosensitive polyimide resin composition comprising (A) a polyamic acid having, in its main chain, repeating units formed from a polycondensation product of at least one tetracarboxylic acid or tetracarboxylic anhydride thereof with at least one diamine compound, and having actinic ray-sensitive functional groups at both terminals thereof; (B) a photosensitive auxiliary having a photopolymerizable functional group; (C) a photopolymerization initiator; and (D) a solvent, wherein 1 the polyamic acid is such that when the repeating unit represented by the formula (1) is defined as a unit molecular weight, a unit molecular weight per carboxyl group (unit molecular weight/COOH) falls within a range of from 200 to 300, and 2 the photosensitive resin composition permits the formation of a polyimide film having a residual stress of 40 MPa or lower and a coefficient of thermal expansion of 30 ppm/.degree. C.

Abstract: A diamine which is useful in preparing a new flexible polyamide and polyimide with an aromatic dicarboxylic acid and a tetracarboxylic dianhydrides, respectively, has a general formula as follows: ##STR1## wherein R.sub.1 is methyl (--CH.sub.3) and n is an integer ranging from 1 to 4.

Abstract: A compound of the formula: ##STR1## wherein Ar.sup.

Abstract: A polyimide precursor solution having a high concentration yet low viscosity, a polyimide coating film having satisfactory physical properties which is prepared from the polyimide precursor solution, and a process for producing a polyimide coating film using the polyimide precursor solution. The polyimide precursor solution has dissolved therein a specific salt of a diamine and a tetracarboxylic acid and/or a dicarboxylic acid-dialkyl ester in a high concentration, the diamine and the tetracarboxylic acid and/or the dicarboxylic acid-dialkyl ester being capable of forming a polyimide. Also disclosed is a polyimide coating film obtained by heating the solution to cause imidization and a process for producing the polyimide coating film.

Abstract: Bischloroformate oligomer compositions are prepared by passing phosgene into a heterogeneous aqueous-organic mixture containing at least one dihydroxyaromatic compound, with simultaneous introduction of a base at a rate to maintain a specific pH range and to produce a specific volume ratio of aqueous to organic phase. By this method, it is possible to employ a minimum amount of phosgene. The reaction may be conducted batchwise or continuously. The bischloroformate composition may be employed for the preparation of cyclic polycarbonate oligomers or linear polycarbonate, and linear polycarbonate formation may be integrated with bischloroformate composition formation in a batch or continuous process.

Abstract: There is disclosed an organic optical component prepared from a resin essentially comprising one or more repetitive structural units selected from the group consisting of structures represented by general formula (1); ##STR1## wherein A is either of the groups below. ##STR2## This invention provides an organic optical component with excellent transparency, heat resistance and mechanical strength as well as a low birefringence. This invention also provides a novel aromatic polyamide with a low permitivity and excellent transparency, processability and thermal stability, besides excellent heat resistance inherent in an aromatic polyamide.

Abstract: The polyimides are derived from solutions of at least one low-boiling organic solvent, e.g. isopropanol containing a mixture of polyimide-forming monomers. The monomeric solutions have an extended shelf life at ambient (room) temperatures as high as 80.degree. C. and consist essentially of a mixture of monoalkyl ester-acids, alkyl diester-diacids and aromatic polyamines wherein the alkyl radicals of the ester-acids are derived from lower molecular weight aliphatic secondary alcohols having 3 to 5 carbon atoms per molecule such as isopropanol, secondary butanol, 2-methyl-3-butanol, 2 pentanol or 3-pentanol. The solutions of the polyimide-forming monomers have a substantially improved shelf-life and are particularly useful in the aerospace and aeronautical industry for the preparation of polyimide reinforced fiber composites such as the polyimide cured carbon composites used in jet engines, missiles, and for other high temperature applications.

Abstract: The present invention provides a novel soluble polyimide resin which is superior in solubility in solvents and transparency, which is useful particularly in electronics and optronics fields, and which has good processability; a process for production of the resin; and a solution composition of the resin. A soluble polyimide resin containing, as part or the whole of the diamine units, a 2,5(or 6)-bis(aminomethyl)bicyclo[2.2.1]heptane and having a light transmittance of 60% or more in a range of wavelength larger than 400 nm in an ultraviolet-visible light spectrum measured for a film of 10-.mu.m thickness; a process for production of the resin; and a solution composition of the resin.

Abstract: A polyimide for optical communications has a monomer, represented by the formula (1), as a repeating unit: ##STR1## wherein X.sub.1 and X.sub.2 are independently selected from the group consisting of halogen atom, halogenated alkyl group, halogenated aromatic ring group, --NO.sub.2, --OR.sup.1 and --SR.sup.1 (where R.sup.1 is selected from the group consisting of halogenated alkyl and halogenated aromatic ring groups); and Z is selected from the group consisting of divalent halogenated aliphatic hydrocarbon, divalent halogenated aliphatic cyclic hydrocarbon and divalent halogenated aromatic hydrocarbon. Thus, light absorption loss at a near infrared light wavelength range can be minimized by using the polyimide, so that the polyimide is very useful as an optical material in the optical communications field using light of a near infrared light region.

Abstract: Polyimide is produced by reacting two kinds of diamine compounds consisting of diaminopolysiloxane and a hydroxyl group-containing diamine or three kinds of diamine compounds consisting of diaminopolysiloxane, a hydroxyl group-containing diamine and an aromatic or alicyclic diamine with a 4,4'-(hexafluoroisopropylidene)diphthalic acid dianhydride, thereby once forming a polyamic acid, and subjecting the polyamic acid to polyimidization reaction. The resulting polyimide itself is soluble in low boiling organic solvents for general purpose use, typically methyl ethyl ketone. A photosensitive composition comprising the polyimide, a photo crosslinking agent and a photo acid-generating agent forms a negative type polyimide pattern upon development with an aqueous alkali solution.

Abstract: The present invention provides polyimides and co-polyimides that are organosoluble. The polyimides and co-polyimides are prepared from an aromatic diamine having tert-butyl group, i.e., 1,4-bis(4-aminophenoxy)-2-tert-butyl-benzene, or its mixture with other diamines, and a mixture of dianhydrides that containing DSDA or 6FDA or other diether-dianhydrides.

Abstract: Disclosed is an aligning film having good liquid crystal orientation, which can be obtained by irradiating polyimide comprising N-(2-(3,5-diaminobenzoyl)oxyethyl)-.alpha.-phenylmaleimide and 1,2,3,4-cyclobutanetetracarboxylic dihydride with polarized UV-rays without employing such methods as rubbing treatment and oblique deposition.

Abstract: Disclosed is a process which comprises the steps of (a) providing a polymer containing at least some monomer repeat units with halomethyl group substituents which enable crosslinking or chain extension of the polymer upon exposure to a radiation source which is electron beam radiation, x-ray radiation, or deep ultraviolet radiation, said polymer being of the formula ##STR1## wherein x is an integer of 0 or 1, A is one of several groups, as specified in the claims, and B is one of several groups, as specified in the claims or mixtures thereof, and n is an integer representing the number of repeating monomer units, and (b) causing the polymer to become crosslinked or chain extended through the photosensitivity-imparting groups. Also disclosed is a process for preparing a thermal ink jet printhead by the aforementioned curing process.

Abstract: The new diamine, "3,3',5,5'-tetramethyl-2,2-bis[4-(4-amino-phenoxy)phenyl]propane" was synthesized and used to prepare high performance soluble engineering plastics by polycondensation. The polymer can be polyamides, polyimides or poly(amide-imide)s. These polymers exhibit excellent solubility, processability, heat resistance and mechanical performance.

Abstract: A composition for a polyimide type liquid crystal aligning film characterized in that a diamino compound constituting polyimide contains one, two or more diamine selected from 4,4'-diaminodiphenyl methane, 3,3'-dimethyl-4,4'-diaminodiphenyl methane, 2,2'-dimethyl-4,4'-diaminodiphenyl methane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenyl methane and 4,4'-ethylene di-meta-toluidine.

Abstract: Electronic parts and a process for manufacturing the electronic parts are provided. The electronic parts comprise an electric insulating material exhibiting a high heat resistance and low dielectric constant as a structural component. The electric insulating material is formed of a polyimide containing a recurring unit represented by the following general formula (1).

Abstract: A diamine-containing polyamic acid alignment layer material provided by the polymerization of aromatic diamine and dianhydride, and having an excellent coating, adhesion and stability. After the polyamic acid alignment layer material is coated and cured at a high temperature, a polyamic acid alignment layer having a pretilt angle of below 2 degrees is formed due to a close ring reaction. The polyamic acid alignment layer with a low pretilt angle can be used in a TN (twisted nematic) type liquid crystal display.

Abstract: A process for making a crystallizable aromatic polymer comprises polycondensing difunctional monomers in the presence of a base and adding to the reaction mixture a nucleating agent. The nucleating agent comprises a nucleophilic group and a group of formula --A--X, where X is a metal cation and A is an anion. It is selected to give an increase in the peak crystallization temperature of the nucleated polymer compared to the unnucleated polymer.

Abstract: This invention relates the novel diamines, the polyimide oligomers and the polyimides derived therefrom and to the method of preparing the diamines, oligomers and the polyimides. The thermoplastic polyimides derived from the aromatic diamines of this invention are characterized as having a high glass transition temperature, good mechanical properties and improved processability in the manufacture of adhesives, electronic and composite materials for use in the automotive and aerospace industry. The distinction of the novel aromatic diamines of this invention is the 2,2',6,6'-substituted biphenyl radicals which exhibit noncoplanar conformation that enhances the solubility of the diamine as well as the processability of the polyimides, while retaining a relatively high glass transition temperature and improved mechanical properties at useful temperature ranges.

Abstract: An optical alignment composition including self-photosensitive polyimide having a benzophenone moiety and an active hydrogen moiety, and an LCD having the alignment layer formed of the optical alignment composition are provided. Since the alignment layer with excellent thermal stability and improved pretilt angle is obtained, the LCD having excellent performance can be manufactured.

Abstract: The present invention provides a series of easily processable poly(ether-imide)s that are organic-soluble and can afford colorless films, their organic solutions and their manufacturing process. The poly(ether-imide) is prepared from a dianhydride and a diamine, wherein the dianhydride is a bis(ether anhydride) having tert-butyl group, i. e. 1,4-bis(3,4-dicarboxyphenoxy)-2-tert-butylbenzene dianhydride.

Abstract: The invention herein relates to a novel soluble polyimide resin comprising polyalicyclic structures and the process of preparation of the same, wherein aromatic tetracarboxylic dianhydride and novel aromatic diamine having an polyalicyclic group with various structures are used to yield a novel form of a polyimide resin, which has superior heat-resistance, solubility, and transparency.More specifically, the invention herein relates to a novel polyimide resin having excellent heat-resistance and solubility, which is prepared by means of reacting diamine monomers having a novel chemical structure with various types of aromatic carboxilic dianhydrides, in stead of aromatic diamine used for the preparation of the conventional polyimide resin. As a result, the polymers so obtained had the glass transition temperature of 260.degree. C..about.410.degree. C. and showed a increase in solubility in proportion to the increase in a number of the aromatic rings between two phenyl groups.

Abstract: The invention herein relates to a soluble polyimide resin for a liquid crystal alignment layer and the manufacturing method thereof, wherein a mixture of aliphatic tetracarboxylic acid dianhydrides and aromatic diamine having aliphatic side chains are used to yield a soluble polyimide resin which has superior heat-resistance, solubility, surface hardness, transparency and liquid crystal alignment capacity.The soluble polyimide resin having alkoxy substituents, for a liquid crystal layer, according to the present invention, is manufactured by adding a mixture of dioxotetrahydrofuran 3-methylcyclohexene-1,2-dicarboxylic dianhydride, which is an aliphatic tetracarboxylic acid dianhydride and aromatic tetracarboxylic acid dianhydride to a mixture of aromatic diamine, and said dioxotetrahydrofuran 3-methylcyclohexene- 1,2-dicarboxylic dianhydride is used in the amount of 50 to 99 mol % to the total amount of anhydrides.

Abstract: Fluorinated polymides comprising units of 2,2',5,5',6,6'-hexafluorobiphenyl-3,3',4,4'-tetracarboxylic dianhydride and aromatic diamines.

Abstract: This invention relates the novel diamines, the polyimide oligomers and the polyimides derived therefrom and to the method of preparing the diamines, oligomers and the polyimides. The thermoplastic polyimides derived from the aromatic diamines of this invention are characterized as having a high glass transition temperature, good mechanical properties and improved processability in the manufacture of adhesives, electronic and composite materials for use in the automotive and aerospace industry. The distinction of the novel aromatic diamines of this invention is the 2,2',6,6'-substituted biphenyl radicals which exhibit noncoplanar conformation that enhances the solubility of the diamine as well as the processability of the polyimides, while retaining a realatively high glass transition temperature and improved mechanical properties at useful temperature ranges.

Abstract: A bis(trisubstitutedtrimellitic anhydride) derivative and a polyesterimide for optical communications, the polyesterimide being formed therefrom. The polyesterimide has a high refractive index, so that when using such polyesterimide as a material for a core of an optical fiber, the range of materials that can be selected for the cladding becomes wide. Also, a coating property and adhesion to a substrate are improved, thereby providing a good film forming property and thermal stability. Also, because the polyesterimide can minimize optical loss at a near infrared wavelength range, the polyesterimide is very useful as an optical material in the optical communications field adopting the light of near infrared wavelength.

Abstract: The invention herein relates to a soluble polyimide resin and the process of preparation of the same, wherein aromatic tetracarboxylic dianhydride and aromatic diamine having an alicyclic group with various structures of substituted alkyl groups are used to yield a novel form of a polyimide resin, which has superior heat-resistance, solubility and transparency.More specifically, the invention herein relates to a novel polyimide resin having excellent heat-resistance and solubility, which is prepared by means of reacting aromatic diamine monomers having a novel chemical structure with various types of aromatic tetracarboxilic acid dianhydrides, in stead of aromatic diamine used for the preparation of the conventional polyimide resin. As a result, the polymers so obtained had the glass transition temperature of 250.degree. C..about.400.degree. C. and showed a increase in solubility in proportion to the increase in volume of the alkyl group.

Abstract: The object of the present invention is to provide polyimide composition having such excellent property as low water absorption and low hygroscopic swelling, and a base tape for a TAB carrier tape and a FPC.The another object of the present invention is to provide polyimide composition comprising polyimide consisting of a repeating unit of the general formula (1): ##STR1## The further object of the present invention is to provide a base tape for a TAB carrier tape containing polyimide film made from said polyimide composition as a base film and a FPC containing polyimide film made from said polyimide composition as an insulating material.

Abstract: A polyamideimide for optical communications, having a minimum light absorption loss in a near infrared light wavelength range, high thermal stability and excellent film processibility, and a method for preparing the same are provided. The polyamideimide has a higher refractive index than the conventional fluorinated polyamideimide. Thus, when using such polyamideimide as a material for a core of an optical fiber, the selection range on the material for cladding becomes wide. Also the coating property and adhesiveness to a substrate are improved, thereby providing a good film processibility and heat resistance.

Abstract: Novel molten-salt type polyelectrolytes are disclosed which contain as an essential ingredient a molten salt polymer obtained by reacting an imidazolium derivative, such as a 1,3-dialkylimidazolium halide, 1,2,3-trialkylimidazolium halide, 1-vinyl-3-alkylimidazolium halide, or 1-vinyl-2,3-alkylimidazolium halide, with an acid monomer, a poly(vinylsulfonamide), trifluoromethanesulfonimide, or the like. The electrolytes show high ionic conductivity at room temperature and have excellent stability to temperature fluctuations and excellent mechanical properties.

Abstract: A photosensitive polyimide, which comprises a copolymer of (A) three diamine compounds mixture consisting of a diaminopolysiloxane, a hydroxyl group-containing diamine or carboxyl group-containing diamine and 1,4-bis[2-(3-aminobenzoyl)ethenyl]benzene with (B) an aromatic tetrocarboxylic acid dianhydride or a dicarboxylic anhydride having a 2,5-dioxotetrahydrofuryl group as one acid anhydride group, is soluble in all-purpose low boiling organic solvents, typically methyl ethyl ketone and provides a negative type photosensitive polyimide, which is developable with an aqueous alkaline solution.

Abstract: Disclosed is a process which comprises reacting a polymer of the general formula ##STR1## or ##STR2## wherein x is an integer of 0 or 1, A is one of several specified groups, such as ##STR3## B is one of several specified groups, such as or mixtures thereof, and n is an integer representing the number of repeating monomer units, with a halomethylethyl ether, a hydrohalic acid, and acetic acid in the presence of a halogen-containing Lewis acid catalyst, thereby forming a halomethylated polymer.

Abstract: A polyamideimide for optical communications, having a minimum optical loss in a near infrared light wavelength range, high thermal resistance and good film processibility, and a method for preparing the same are provided. The polyamideimide is very useful as an optical material in the optical communications field adopting the light of near infrared light wavelength.

Abstract: The invention herein relates to a soluble polyimide resin for a liquid crystal alignment layer and the process of preparation of the same, wherein aliphatic tetracarboxylic dianhydride and aromatic diamine having the amide group are used to yield a novel form of a polyimide resin having superior heat-resistance, solubility, transparency, and liquid crystal alignment capacity.More specifically, the invention herein relates to a novel polyimide resin having excellent heat-resistance, solubility, liquid crystal alignment property, and high pretilt angle, which is prepared by means of jointly using the aromatic diamine, used for the preparation of the conventional polyimide resin, and the aromatic diamine having a long alkyl chain with a substituted amide group, and reacting the same with various types of carboxylic dianhydride.

Abstract: A fluororesin sheet is disclosed which comprises an aromatic polyamide pulp and a fluororesin as an essential component, the tensile strength of the fluororesin sheet being not less than about 250 kg/cm.sup.2. A process for producing this fluororesin sheet comprises dispersing the aromatic polyamide pulp and the fluororesin powder in water, adding a coagulating agent which destabilizes the dispersing of the fluororesin powder to the dispersion to deposit the fluororesin powder on the surface of the aromatic polyamide pulp, paper-making, followed by drying to obtain a sheet article, and compressing the sheet article using a roller, followed by heating.

Abstract: Disclosed is a composition which comprises a polymer containing at least some monomer repeat units with water-solubility- or water-dispersability-imparting substituents and at least some monomer repeat units with photosensitivity-imparting substituents which enable crosslinking or chain extension of the polymer upon exposure to actinic radiation, said polymer being of the formula ##STR1## wherein x is an integer of 0 or 1, A is one of several specified groups, such as ##STR2## B is one of several specified groups, such as ##STR3## or mixtures thereof, and n is an integer representing the number of repeating monomer units. In one embodiment, a single functional group imparts both photosensitivity and water solubility or dispersability to the polymer. In another embodiment, a first functional group imparts photosensitivity to the polymer and a second functional group imparts water solubility or dispersability to the polymer.

Abstract: 2.2'-bis(3-mercaptophenyl)hexafluoropropane [bisthio-phenol AF] is obtained in good yield by chlorosulfonating 2.2'-bisphenylhexafluoropropane and reducing the thus quantitatively obtained 2,2'-bis(3-chlorosulfonylphenyl)-hexafluoropropane with zinc under acidic conditions and is effectively used as a cross-linking agent for a fluorine-containing elastomer having halogenophenyl groups as cross-linkable groups.

Abstract: A new holographic substrate utilizing flexible, optically transparent fluorinated polyimides. Said substrates have extremely low birefringence which results in a high signal to noise ratio in subsequent holograms. Specific examples of said fluorinated polyimides include 6FDA+APB and 6FDA+4BDAF.

Abstract: The present invention provides a series of easily processable poly(ether-imide)s that are organic-soluble and can afford colorless films, their organic solutions and their manufacturing process. The poly(ether-imide) is prepared from a dianhydride and a diamine, wherein the dianhydride is a bis(ether anhydride) having tert-butyl group, i.e. 1,4-bis(3,4-dicarboxyphenoxy)-2-tert-butylbenzene dianhydride. The present invention is also directed to synthesis of this special dianhydride.

Abstract: A novel polyimide having a repeating structure unit expressed by the following general formula (1), a method for manufacturing the same, a gas separation membrane using the novel polyimide and the method for manufacturing the same. The gas separation membrane using this polyimide is excellent in gas permeable performance and separation selectivity for gas, for example, carbon dioxide, methane, etc.General Formula (1) ##STR1## where R denotes a quadrivalent organic group.

Abstract: An angularity enhancement layer in a liquid crystal display, which display comprises a liquid crystal cell, wherein the angularity enhancement layer includes a negative birefringent polyimide layer comprising a plurality of structural units having pendant fluorene groups, said angularity enhancement layer being disposed on at least one surface of said liquid crystal cell. A liquid crystal display can comprise an angularity enhancement construction of the invention which comprises a polyimide layer.

Abstract: The morphology of multidimensional, thermally stable oligomers is combined with the inclusion of charge carrier linkages within the polymer arms to produce thermally stable advanced composites from cured oligomers that are conductive or semiconductive if suitably doped.

Abstract: The disclosure describes a process for preparing a polyamideimide resin having high molecular weight in a simple manner wherein major problems of the prior processes such as low heat resistance and low melt flowability are improved. The process comprises condensation of an aromatic tricarboxylic acid anhydride and an aromatic diamine in a polar solvent, subjecting the resulting diimidedicarboxylic acid to acyl halogenating agent treatment to give an intermediate having good reactivity at low temperature, and then subjecting the latter to direct polymerization by using diamine as a nucleophilic agent to give a polyamideimide resin having high molecular weight. The polyamideimide resin prepared by the present invention can be used as major heat resistant structural material in advanced industries and as paint, sheet, adhesives, sliding material, fiber and film having heat resistance.

Abstract: Methylenedianiline-free, PMR-type, curable compositions based on m-phenylenediamine or mixtures of m-phenylenediamine and p-phenylenediamine are described.

Abstract: This invention relates to a poly (imide amic ester) random copolymer, a precursor thereof, and a process for preparing the same. Specifically this invention relates to a novel precursor of polyimide, poly(imide amic ester) which is chemically stable and has excellent workability in either liquid or solid state, a polyimide obtained therefrom and a process for preparing the same.

Abstract: This invention relates the novel diamines, the polyimide oligomers and the polyimides derived therefrom and to the method of preparing the diamines, oligomers and the polyimides. The thermoplastic polyimides derived from the aromatic diamines of this invention are characterized as having a high glass transition temperature, good mechanical properties and improved processability in the manufacture of adhesives, electronic and composite materials for use in the automotive and aerospace industry. The distinction of the novel aromatic diamines of this invention is the 2,2',6,6'-substituted biphenyl radicals which exhibit noncoplanar conformation that enhances the solubility of the diamine as well as the processability of the polyimides, while retaining a realatively high glass transition temperature and improved mechanical properties at useful temperature ranges.

Abstract: The present invention relates to amine compositions and the preparation of polyimides. The polyimides can be used for inducing alignment of a liquid crystal medium with polarized light and liquid crystal display elements.

Abstract: Copolyetherimides are prepared by the reaction of an alkali metal salt of a dihydroxyaromatic compound with a bis(substituted phthalimide) and a third compound which may be a substituted aromatic ketone or sulfone or a macrocyclic polycarbonate or polyarylate oligomer. The reaction takes place the in presence of a solvent and a phase transfer catalyst having high thermal stability, such as a hexaalkylguanidinium halide. Random or block copolymers may be obtained, depending on the reaction conditions.