82 results about "Sulfinic acid" patented technology

The invention belongs to the field of preparation of medical intermediates, and particularly relates to a preparation method of an On-DNA sulfinic acid structure compound. The method for preparing the On-DNA sulfinic acid structure compound comprises a step of oxidizing On-DNA thiol (phenol) into the On-DNA sulfinic acid structure compound under alkaline and heating or illumination conditions, a solvent used in the reaction step is a mixed solution of water, dimethyl sulfoxide, N, N-dimethylformamide, acetonitrile, ethanol or tetrahydrofuran, the reaction temperature is not more than 80 DEG C, and the reaction time is not more than 2 hours. And the illumination wavelength ranges from 365 nanometers to 535 nanometers. The On-DNA sulfinic acid structure compound obtained in the invention can be directly used for constructing a structure compound with a sulfonyl group, the reaction condition is mild and convenient, a new method and a new idea are provided for construction of a DNA coding compound library, and the On-DNA sulfinic acid structure compound has a very good application prospect in lead drug development.

The invention provides a sulfinate organic positive alkali metal ion supplement for a secondary battery, and relates to the technical field of secondary batteries. The organic positive electrode alkali metal ion supplement has a structure as shown in the following general formula: [R-SO2]-M < + >, wherein M < + > is a metal cation and is selected from at least one of Li < + >, Na < + > and K < + >; [R-SO2]-is a sulfinate anion, and wherein R is an organic group. The supplement compensates irreversible capacity loss by efficiently releasing active ions, so that the energy density of the battery is improved; the oxidation potential is proper, the environmental stability is excellent, and the catalyst is not needed to decompose and easy to process; decomposition products are harmless, an electrode interface can be optimized, and the cycle life of the battery is remarkably prolonged.

The invention provides an isosulfinate electrolyte additive for a lithium secondary battery and a non-aqueous electrolyte, and relates to the technical field of lithium secondary batteries. The non-aqueous electrolyte for the lithium secondary battery is characterized by comprising a non-aqueous organic solvent, a conductive lithium salt electrolyte and a sulfinic acid isosalt electrolyte additive for the lithium secondary battery. According to the additive, a sulfur-rich stable SEI membrane is constructed by utilizing a sulfinic acid group, impedance is reduced, the additive adapts to electrode volume change, and the cycle life is prolonged; dissimilar alkali metal ions optimize a solvation structure and form a mixed interface, so that a desolvation energy barrier is reduced, and low-temperature and rate performance is improved; meanwhile, the electrostatic shielding effect of large-radius positive ions can guide uniform deposition of lithium, dendritic crystals and dead lithium are inhibited, and the safety of the battery is enhanced.

The invention discloses an asymmetric disulfide reagent (R1O-SS-SO2R2) as shown in a formula (3) and a synthesis method thereof, R1O-SS-OR1 as shown in a formula (1) and hyposulfonic acid as shown in a formula (2) are taken as reaction raw materials, no catalyst additive is needed, and the asymmetric disulfide reagent (R1O-SS-SO2R2) compound is obtained through reaction. The method has the advantages of mild reaction conditions, cheap and easily available raw materials, simple reaction operation, high yield, no need of any catalyst additive in the reaction, economy, practicability and environmental friendliness; reaction substrates are easy to prepare; the reaction efficiency is high after reaction amplification. The asymmetric disulfide reagent (R1O-SS-SO2R2) provided by the invention can be used for preparing an asymmetric polysulfide compound. The invention also discloses an asymmetric polysulfide compound synthesized by using the asymmetric disulfide reagent (R1O-SS-SO2R2) as shown in the formula (3) and a synthesis method of the asymmetric polysulfide compound. The method has wide application prospect and practical value.

The invention provides a synthesis method of a negative charge highly delocalized sulfonyl imide alkali metal salt {[(R3SO2) (R2 (R1SO2N) SO) N] M), M = Li, Na, K, Rb or Cs}. The synthesis method comprises the following steps: carrying out oxidation and fluorination reaction on alkyl (S-alkyl sulfonyl imide) potassium sulfinate (or rubidium or cesium) and an N-fluorine electrophilic reagent to synthesize alkyl (S-alkyl sulfonyl imide) sulfonyl fluoride with the yield of 70-90%; the obtained alkyl (S-alkyl sulfimide) sulfonyl fluoride and sulfamide containing substituent R3 or alkali metal salt thereof are subjected to nucleophilic substitution reaction, the product is purified to obtain the high-purity negative-charge highly-delocalized sulfimide alkali metal salt, and the method has the characteristics that the operation is simple, the raw materials are low in price, the product is easy to separate and purify, the method is suitable for industrial mass production, and the like; and the prepared negative charge highly delocalized sulfimide alkali metal salt is high in chemical stability and good in solubility, and is a preferable electrolyte material for realizing high-specific-energy power and energy storage batteries.

The application relates to the technical field of organic synthesis, and discloses an organic sulfinate salt composition, a preparation method and application thereof and the composition. The preparation method comprises the following steps: contacting a monovalent organic sulfinate salt shown in formula I with a divalent metal salt or a salt of a metal with a valence higher than two under the condition that a poor solvent exists; the organic sulfinate salt prepared by the method has high yield and high purity, almost no sulfinate salt by-product is generated, the method has the advantages of simple operation, safe and easily-obtained reaction raw materials, rapid reaction, no need of recrystallization, the target product can be obtained through filtration after the reaction, less solvent is used, the cost is low, etc., the composition has the beneficial effects that the composition is more stable than a corresponding sodium salt, the sulfur odor is reduced, the composition has strong reducing capacity, etc.

The invention relates to a synthetic method of a deuterated methyl selenide compound, which is characterized in that aromatic amine and deuterated methyl selenyl benzene sulfinate are subjected to Sandmeyer reaction in an organic solvent under the air condition and the action of tert-butyl nitrite to obtain the deuterated methyl selenide compound. The method has the advantages of simple reaction conditions and high product yield and purity, develops a new synthesis route and method for preparation of the deuterated methyl selenide compound, and has good application potential and research value.

The invention belongs to the technical field of preparation of sulfur-containing compounds, and particularly relates to a method for electrochemical synthesis of a sulfur-containing compound by taking sodium sulfinate as a sulfur source. In an inert atmosphere, an indolone compound or a 2-ester benzocyclic ketone compound is taken as a raw material and is respectively mixed with a sodium sulfinate compound, and under the action of alkali, an electrolyte and a cathode reduction hydrogen source, the 2-thioether-2-ester benzocyclic ketone compound with the structural formula shown in the specification is prepared by adopting an organic electrosynthesis method in a solvent at room temperature. Aiming at the defects of stink emission when mercaptan is used as a sulfur source, by-product increase caused by the participation of an oxidizing agent in a reaction and complex synthesis of an electrophilic sulfuration reagent in a carbon-sulfur bond construction process in a traditional method, the invention develops a method for synthesizing a carbon-sulfur bond by using a sodium sulfinate compound as a green sulfur source. An electrochemically mediated C (sp3)-S bond construction strategy is carried out under the condition of no exogenous catalyst, and efficient thioetherification of an activated C (sp3)-H bond is realized under a mild condition.

The invention discloses a synthesis process of high-yield sodium benzenesulfinate, and belongs to the technical field of synthesis of sodium benzenesulfinate. The synthesis process of the high-yield sodium benzenesulfinate comprises the following preparation steps: S1, mixing a first catalyst, sodium hydroxide and a first solvent, then adding powdered sulfur, reacting for a first reaction time under microwave radiation, then adding chlorobenzene, continuously reacting for a second reaction time under microwave radiation, then filtering, carrying out reduced pressure distillation to remove the solvent, and recrystallizing, so as to obtain the high-yield sodium benzenesulfinate. The diphenyl disulfide is obtained; s2, mixing the diphenyl disulfide prepared in the step S1, alcohol, an oxidizing agent and a second solvent, stirring in the air at room temperature for a third reaction time, diluting with ultrapure water, extracting with ethyl acetate for multiple times, combining organic layers, drying, concentrating and purifying to obtain benzene sulfinate, and keeping in a dark place and in an oxygen-isolated manner; s3, under the dark and nitrogen conditions, benzene sulfinate prepared in the step S2 is hydrolyzed and refined under the alkaline condition, and sodium benzene sulfinate is obtained.

The application relates to an alpha-sulfonimidate compound, a chemoselective preparation method and application, and belongs to the technical field of organic synthesis. The alpha-sulfonimidate compound is prepared by using a nitroalkene and sodium sulfinic acid as raw materials in a solvent at room temperature without a metal catalyst under an air atmosphere. Compared with a previously reported preparation method, the application has the advantages of being green, environment-friendly, safe, efficient and energy-saving, the substrate has a wide application range, the product has good functional group compatibility, the raw material is easy to obtain, and no transition metal and external NO source are needed, and the application can be used for simply and efficiently synthesizing a medical intermediate and a molecule.

This invention provides an alkali-generating agent and a curable resin composition that exhibit excellent storage stability in a liquid, high catalytic activity at the desired curing temperature, and induce a curing reaction in a short time. An alkali-generating agent comprises a pyridinium cation and an anionic residue of an organic or inorganic acid, and is represented by the following formula (a). (In formula (a), A represents a divalent hydrocarbon group with 1 to 8 carbon atoms that may contain heteroatoms; R1 to R5 independently represent hydrogen atoms or electron-donating groups; R1 and R2, R2 and R3, R3 and R4, and R4 and R5 can be bonded to form a ring structure. R6 to R5...) 10 Each of the following groups independently represents a hydrogen atom, halogen atom, hydroxyl group, alkoxy group, mercapto group, sulfide group, silyl group, silanol group, nitro group, nitroso group, cyano group, sulfinic acid group, sulfonyl group, sulfonic acid group, phosphono group, oxophosphono group, phosphonyl group, phosphonate group, amino group, or ammonium group, R6 and R7, R7 and R8, R8 and R9, R9 and R 10 They can be bonded separately to form a ring structure.

The present invention provides a double metal layered hydroxide represented by the formula [M(II) 1‑x M(III) x (OH)2] x+ (A n‑ ) x / n ·mH2O, wherein M(II) contains a divalent cation selected from at least one of Mg, Zn, Ca, Ni, Co, Cu, Fe, Mn, and Sr, M(III) contains a trivalent cation selected from at least one of Al, Fe, Cr, Co, In, Ga, and V, A n‑ contains an anion selected from at least one of CO3 2‑ , OH ‑ , F ‑ , Cl ‑ , SO4 2‑ , NO3 ‑ , PO4 3‑ , B(OH) ‑ , VO4 3‑ , MnO4 ‑ , ClO4 ‑ , a carboxylate, a sulfonate, a sulfinic acid, and a thiocarboxylate, x is 0 < x < 1, n is the valence of A, and m is a number of 0 or more, and the double metal layered hydroxide has an average particle diameter D50 of 0.3 to 1.0 μm, a BET specific surface area of 8 to 25 m 2 / g, and a crystallite size of a D003 plane of 340 to 400 angstroms.

This disclosure relates to a polishing composition comprising at least one abrasive; at least one nitride removal reducing agent; an acid or alkali; and water. The at least one nitride removal reducing agent may include C... 12 To C 40 The polishing composition comprises a hydrophobic portion of a hydrocarbon group and a hydrophilic portion containing at least one group selected from the group consisting of sulfinic acid, sulfate, sulfonic acid, carboxyl, phosphate, and phosphonic acid groups; wherein the hydrophobic and hydrophilic portions are separated by 0 to 10 epoxy alkyl groups. The polishing composition may have a pH of about 2 to about 6.5.

Provided are a base generator, a curable resin composition, and a printed wiring board, which have excellent storage stability in a one-component form and exhibit high catalytic activity at a desired curing temperature to cause a curing reaction in a short time. A base generator represented by the following formula (a), which comprises an imidazolium cation and an anion residue of an organic acid or an inorganic acid. [Formula 1] TIFF0007819427000026.tif22170In formula (a), A represents a divalent group of 1 to 8 carbon atoms which may contain a heteroatom, R1 to R4 each independently represent a hydrogen atom, an alkyl group of 1 to 8 carbon atoms which may have a substituent, an aryl group of 6 to 20 carbon atoms which may have a substituent, or an alkylaryl group of 7 to 20 carbon atoms which may have a substituent, and R1 and R2, R2 and R3, and R3 and R4 may each bond to form a ring structure. R5 to R9 each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, a halogen atom, a hydroxyl group, an alkoxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a cyano group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, or an ammonio group, and R5 and R6, R6 and R7, R7 and R8, and R8 and R9 may each bond to form a ring structure. - is the anionic residue of an organic or inorganic acid.

The invention discloses a mechanochemical synthesis method of a sulfonyl methyl benzoic acid compound, which comprises the following steps: mixing benzyl substituted benzoic acid, aryl sodium sulfinate and an inorganic substance, and carrying out solid-phase nucleophilic substitution reaction through mechanochemical grinding under a solvent-free condition to obtain the sulfonyl methyl benzoic acid compound. Cheap and easily available aryl sodium sulfinate and benzyl substituted benzoic acid are used as raw materials, the target product is prepared by carrying out nucleophilic substitution reaction under a solid phase condition by adopting mechanochemical grinding, the synthesis process is simple, convenient, green and environment-friendly, and the obtained target product is high in yield and purity and suitable for industrial production.

This invention relates to the field of organic synthesis technology, and more particularly to a method for preparing sulfone-substituted indene compounds. The method involves mixing a propargyl alcohol compound, a sodium sulfinate compound, an acid promoter, and a solvent, and carrying out a tandem sulfonation-cyclization reaction to obtain the sulfone-substituted indene compound. This method has the advantages of readily available raw materials, no catalyst required, ease of operation, and being green and efficient, showing good prospects for industrial application.

A dental ceramic blank comprising at least one organic compound, characterized in that the blank has an open-pore ceramic framework, wherein the open-pore ceramic framework is selected from an open-pore dental ceramic framework comprising zirconia, aluminum oxide, a mixed oxide comprising zirconia, and / or silicon carbide, wherein the open-pore ceramic framework contains 2 to 50 wt.% of at least one organic compound selected from a) comprising at least one polymerizable monomer and / or a mixture of polymerizable monomers, thermal initiators comprising peroxide and / or an azo compound or a redox system comprising a peroxide, and a reducing agent selected from ascorbic acid, an ascorbic acid derivative, barbituric acid or a barbituric acid derivative, sulfinic acid, a sulfinic acid derivative or a redox system (aa) barbituric acid or thiobarbituric acid or a barbituric acid or thiobarbituric acid derivative and (bb) at least one copper salt or copper complex and (cc) at least one compound with an ionic halogen atom, particularly preferably a redox system comprising 1-benzyl-5-phenylbarbituric acid, copper acetylacetonate and benzyldibutylammonium chloride, and / or b) a polymer of the aforementioned monomers polymerized in the blank with respect to the overall composition of the dental ceramic blank.

A method of desulfurizing sulfur-crosslinked rubber includes adding at least one selected from the group consisting of primary and secondary phosphine oxides and analogues of the primary and secondary phosphine oxides, primary and secondary phosphines which become oxides when oxidized and analogues of the primary and secondary phosphines, sulfenic acid, and sulfinic acid as a desulfurizing agent that acts on a sulfur bond in the sulfur-crosslinked rubber and cleaves the sulfur bond to the sulfur-crosslinked rubber, and performing heating.

The application provides a preparation method of sulfonic acid ester in a sulfonic acid water phase, and belongs to the technical field of organic synthesis. The specific preparation method is as follows: aromatic sulfonic acid is added into water without catalyst and redox reagent, and sulfonic acid ester can be obtained by reacting for 2 hours at a temperature of 100 DEG C or above. The method has the advantages of simple raw material, high yield, mild reaction condition, easy control, less waste, and good social value and industrialization prospect.

The present application relates to a kind of preparation of β-sulfonyl methacrylate compound method. Specifically under the condition of oxidation, end alkyne, sodium organic sulfinic acid under carbon monoxide atmosphere one-pot method is prepared. The present application is widely from substrate, commercially available end alkyne and sodium organic sulfinic acid, under oxidation and without transition metal catalysis, by radical process, obtains a series of β-sulfonyl methacrylate compound.

The invention belongs to the field of organic synthesis, and discloses a sulfonylated benzoazepine [1, 2-a] indolone compound and a preparation method thereof. According to the preparation method, under the conditions of room temperature and visible light irradiation, 1-(2-(arylethynyl) benzoyl) indole, aryl thianthrene salt and 4-diazabicyclo [2.2. 2] octane-1, 4-dionium-1, 4-disulfinic acid are used as raw materials, tris (4-methoxyphenyl) amine is used as a catalyst, and the preparation of the sulfonylated benzazepine [1, 2-a] indolone compound is realized. The method has the advantages of mild reaction conditions, simplicity and convenience in operation, no photosensitizer, wide substrate application range and the like. The sulfonylated benzazepine [1, 2-a] indolone compound has potential application value in the research fields of organic synthesis and the like, a novel preparation method is provided for synthesis of the sulfonylated benzazepine [1, 2-a] indolone compound, and part of the synthesized compound has certain antitumor activity.

Described are sulfinate salts and methods of using the same in synthesis. The sulfinate salt may be a salt of formula (I): wherein: a is 1 or 2; X+a is a cation having a +a charge; R1 is hydrogen, -NO2, -OC1-4alkyl, C1-4alkyl, F, or Cl; and R2 is hydrogen, -OC1-4alkyl, C1-4alkyl, or -NO2; with the proviso that at least one of R1 and R2 is not hydrogen.

The presently claimed invention relates to dielectric polishing composition comprising (A) surface - modified colloidal silica particles comprising a negatively - charged group on the surface of the particles, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of from 5 nm to 200 nm, and a zeta potential < -35 mV at a pH in the range of from ≥ 2.0 to ≤ 4.5; (B) at least one buffering agent selected from L-arginine, lysine, or histidine; (C) at least one iron (III) oxidizer; (D) at least one pH adjusting agent selected from 2-amino-2-methyl- propan-1-ol or phosphoric acid and salts thereof; (E) at least one stabilizer; (F) at least one corrosion inhibitor selected from formamidine sulfinic acid, L- cysteine, ethylene thiourea, thiourea, N-(4-pyridyl)thiourea), N-(n-propyl)thiourea, cysteine sulfinic acid, 4-aminobenzene-1- sulfinic acid, N-(2-mercaptopropionyl)glycine, 2-oxooxane-4-sulfonic acid, L-cysteic acid, 2- amino-thiobiuret, L-methionine, or homocysteine; and (G) an aqueous medium, wherein the pH of the composition is in the range of from ≥ 2.0 to ≤ 5.0.

Provided is: a base generator which has excellent storage stability in one liquid, and exhibits high catalytic activity at a desired curing temperature, thereby causing a curing reaction in a short time; a curable resin composition; and a printed wiring board.　This base generator is composed of imidazolium cations and anion residues of an organic acid or an inorganic acid, and is represented by formula (a). In formula (a), A represents a divalent group having 1 to 8 carbon atoms, which may contain a hetero atom, and R1 to R4 each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, which may have a substituent, an aryl group having 6 to 20 carbon atoms, which may have a substituent, or an alkylaryl group having 7 to 20 carbon atoms, which may have a substituent. R1 and R2, R2 and R3, and R3 and R4 may be bonded to each other to form a ring structure. R5 to R9 each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, which may have a substituent, a halogen atom, a hydroxyl group, an alkoxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a cyano group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, or an ammonio group. R5 and R6, R6 and R7, R7 and R8, and R8 and R9 may be bonded to each other to form a ring structure. X- represents an anion residue of an organic acid or an inorganic acid.

The present invention relates to the technical field of chemical synthesis, and specifically discloses a method for electro-oxidative synthesis of a fluoroalkyl-substituted benzo-7-membered nitrogen heterocycle, which specifically comprises the following steps: Step 1, under the condition of passing an electric current, an aryl diazonium salt reacts with a fluorinated sodium methylsulfinate compound in an electrolyte and a solvent to obtain the benzo-7-membered nitrogen heterocycle. Step 2, using the fluorinated sodium methylsulfinate compound to react with a substituted aryl diazonium salt in an electrolyte under the promotion of electricity to generate a benzo-7-membered nitrogen heterocycle compound. In the present invention, no transition metal catalyst is required, and the reaction is carried out only under the action of electric current, which is energy-saving and economical; the free radical source used in the reaction is cheap and easy to obtain, and the cost is low, and the 7-membered nitrogen heterocycle compound can be directly synthesized, which reduces the synthesis cost compared with the prior art.

The invention provides a preparation method of a sulfonylated dihydropyrazole derivative, and belongs to the field of organic synthesis. According to the invention, a (E)-N-allyl-N '-benzyl acethydrazide compound (compound 1), an aryl diazonium salt compound (compound 2) and DABSO (1, 4-diazabicyclo [2.2. 2] octane-1, 4-dionium-1, 4-disulfinic acid) are used as raw materials, and the sulfonylated dihydropyrazole derivative is prepared by a method of catalyzing insertion of sulfur dioxide. According to the preparation method, the problems of corrosion of reagents, expensive metals and excessive oxidizing agents during insertion of SO2 in the prior art are avoided.

The invention provides a fluorinated sulfinate compound, a preparation method and a non-aqueous electrolyte. The structural formula of the fluorinated sulfinate compound is shown as a structural formula I, and R is selected from C1-C6 fluoroalkyl. The fluoro-sulfinate compound comprises a fluorine-containing group substituted alcohol and a fluorine-containing sulfinyl skeleton, has the advantages of both the fluorine-containing group substituted alcohol and the fluorine-containing sulfinyl, can form a good protective film on the interface of positive and negative electrode materials, has relatively low internal resistance, can be used as an additive to improve the rate and low-temperature performance of a battery, and can be applied to the field of lithium ion batteries, such as lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries and lithium ion batteries. Good application prospects are realized.

Disclosed are an antioxidant for a fuel cell having high antioxidant capacity, and an electrolyte membrane and a membrane-electrode assembly including the same, and more particularly, an antioxidant for a fuel cell having high dispersity and / or distribution and excellent antioxidant capacity, and a membrane-electrode assembly including the same. The antioxidant includes a metal oxide and a sulfur-containing organic compound adsorbed on the metal oxide, for example, an organic compound including a sulfinic acid anion group (R-SO2 ‑ ).

The invention discloses a preparation method of a thiocarbamate compound. According to the method, an isocyanide compound and a sulfinic acid compound are used as raw materials, and a series of target products are conveniently prepared under the condition of an oxidizing agent. The method disclosed by the invention has the advantages of cheap and easily available raw materials, mild reaction conditions, very simple reaction system, convenience in operation, good substrate universality, high target product yield, safe production and environmental friendliness, and is suitable for industrial production. According to the process, sulfinic acid compounds are used as raw materials, so that the unpleasant smell of thioether and mercaptan and the hidden danger of safe production in the prior art are avoided; meanwhile, a series of problems that thiosulfonate, sulfonyl hydrazide and the like need to be prepared in advance, the technological process is tedious and the like are solved.

The invention discloses a method for synthesizing a site-selective diaryl sulfone compound, which comprises the following steps of: orderly mixing sodium sulfinate, biaryl lambda 3 bromine salt / chlorine salt, alkali or catalyst and solvent, and stirring at 0 DEG C or 95 DEG C to construct a C-S bond, so that site selectivity control can be realized by adjusting reaction conditions, and the site selectivity of the diaryl sulfone compound is improved. The diversified synthesis of the diaryl sulfone compound is realized. According to the present invention, the synthesis of the diaryl sulfone compound can be efficiently and selectively achieved at the high site, the used starting raw material has characteristics of simple synthesis, diverse structures and low price, the reaction cost is reduced, the post-treatment step of the reaction is simplified, and the construction of the site-selective C-S bond can be achieved. The synthesis reaction operation is simple, the condition is mild, the yield is high, the post-treatment is convenient, the amplification of the reaction and the subsequent conversion of the product can be realized, and the method has wide application prospect and practical value.