207 results about "Diol" patented technology

The invention discloses unsaturated polyester resin for imitation jade handicrafts and a preparation method thereof, and belongs to the technical field of polyester resin. Comprising the following components: diethylene glycol, methylpropanediol, propylene glycol, maleic anhydride, phthalic anhydride, an antioxidant, a polymerization inhibitor, paraffin, a stabilizer, an ultraviolet light absorber, a whitening agent and a diluent. The weight ratio of the propylene glycol to the methyl propylene glycol is (1.0-1.3): 1, and the methyl propylene glycol accounts for 20-22% of the total amount of the dihydric alcohol; the weight ratio of maleic anhydride to phthalic anhydride is (0.46-0.52): 1; the preparation method comprises 1) adding the raw materials and the antioxidant into a reactor, carrying out heating, carrying out heat preservation for 0.5-1.0 h and continuing heating, 2) carrying out a reaction for 2-3 h after heating, carrying out dehydration until an acid value is 20-25 mgKOH / g, and 3) carrying out cooling, adding the auxiliary agent and carrying out uniform mixing so that the unsaturated polyester resin is obtained.

The present invention relates to an energetic perfluoroborate binder, a preparation method thereof and an application thereof, belonging to the technical field of energetic binders. The structural formula of the binder is:; wherein, n is a positive integer less than or equal to 20. The main raw materials of the binder are 1H,1H,2H,3H,3H-perfluorononane-1,2-diol, boric acid and polyazidoglycidyl ether; boric acid forms a borate bond with 1H,1H,2H,3H,3H-perfluorononane-1,2-diol, and polyazidoglycidyl ether is compounded through the boron-nitrogen coordination action with 1H,1H,2H,3H,3H-perfluorononane-1,2-diol, realizing the controllable preparation of the energetic perfluoroborate binder. The energetic perfluoroborate binder has high energy and stable storage, and can improve the energy and mechanical properties of the propellant.

The present invention relates to a processing liquid containing an effective ingredient and water, wherein the effective ingredient contains the following component (A), the following component (B), and the following component (C), • component (A): one or more compounds selected from a specific acetylenic diol and an alkylene oxide adduct thereof, • component (B): a compound containing a copolymerization site of ethylene oxide and another alkylene oxide, and not having a carbon-carbon triple bond, • component (C): a compound containing a copolymerization site of ethylene oxide and another alkylene oxide, not having a carbon-carbon triple bond, and having a higher cloud point than the component (B) at 1 mass% aqueous solution, the content of the component (A) and the total content of the component (B) and the component (C) are in a specific range based on the total amount of the effective ingredient, and the content ratio (A) / (C) of the component (A) and the component (C) and the content ratio (B) / (C) of the component (B) and the component (C) are in a specific range in terms of mass ratio.

A process for making L-glufosinate, the process comprising the following steps: a) reacting a compound according to formula (I), (I), wherein R1 is hydrogen, (C1-C12)-alkyl, (C1-C12)-haloalkyl, (C6-C10)-aryl, (C6-C10)-haloaryl, (C7-C10)-aralkyl, (C7-C10)-haloaralkyl, (C4-C10)-cycloalkyl, or (C4-C10)-halocycloalkyl, with a compound according to formula (II), (II), wherein R2 and R3 are independently from each other (C1-C8)-acyloxy, (C1-C8)-alkoxy or hydroxy, or R2 and R3 form together an epoxide group or an ethylene carbonate group, and optional subsequent acidic treatment to form a diol according to formula (III), (III), b) Oxidizing the diol according to formula (III) to form 2-oxo-4-(hydroxy(methyl)phosphinoyl)butyric acid (PPO); and c) aminating the PPO to L-glufosinate.

The invention relates to a method for preparing a C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol, said method comprising:a) a first step of esterification of 1,4:3,6-dianhydrohexitol with a fatty acid having a C13-C29 alkyl chain, said fatty acid being in excess, so as to form a reaction crude comprising a C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol and unreacted fatty acid;b) a second step of esterification of the unreacted fatty acid with a primary or aromatic diol.

Provided is a resin composition with which it is possible to produce laminates having various kinds of laminate structures that exhibit excellent adhesion and tear-openability without using an aromatic isocyanate, and which does not substantially contain a solvent component and is used as a main agent of a two-liquid curing type adhesive composition capable of being applied in a thin film state. This resin composition is used as a main agent (A) of a two-liquid curing type adhesive composition including the main agent (A) and a curing agent (B) and does not substantially contain a solvent content. The resin composition includes a polyester (a) having hydroxyl groups at molecular terminals at a hydroxy group concentration of 1.0-6.0 mol / kg. The polyester (a) has structural units derived from a dicarboxylic acid (α) and structural units derived from a diol (β). In the structural units derived from the dicarboxylic acid (α), the contained amount of a structural unit derived from an aromatic dicarboxylic acid (α1) is greater than 40 mol%. The melt viscosity of the resin composition at 80°C is 10,000 mPa･s or less.

The invention relates to the field of polyester, and discloses modified polyester as well as a preparation method and application thereof. The modified polyester contains a structural unit A as shown in a formula (I) and a structural unit B as shown in a formula (II), R1 and R2 are respectively and independently C0-C4 alkylene, and R3, R4, R5, R6, R7, Ra, Rb, Rc and Rd are respectively and independently hydrogen or C1-C4 alkyl. The method comprises the following steps: (1) under an esterification reaction condition, mixing a modified monomer, a binary acid monomer, a dihydric alcohol monomer and a catalyst, and carrying out a first-stage reaction to obtain a prepolymer; (2) under the polycondensation reaction condition, mixing the prepolymer with a stabilizer, and carrying out second-stage reaction; wherein the modified monomer contains polyhydric alcohol with a structure as shown in a formula (I) and polybasic acid with a structure as shown in a formula (II). The modified polyester has excellent explosion-proof performance, excellent puncture resistance and better optical performance. # imgabs0 #

Provided is a polymerizable composition including (a) a polymerizable component comprising a diol bis(allyl carbonate) and / or a pre-polymer thereof; and (b) a polymerization initiator component including: (i) a di(C6-C10 alkyl) peroxydicarbonate, and (ii) an organic peroxide having one peroxy, one peroxycarbonate, or one peroxybenzoate group and a 1,1-dimethylalkyl group bonded to a peroxy oxygen, where (ii) comprises a molecular weight ranging from 200 to 250 g / mole, the polymerization initiator (b) is free of diisopropyl peroxydicarbonate, (i) comprises an amount ranging from 4.87% to 7.90% by weight relative to the total solids of the polymerizable composition and (ii) comprises an amount within the range defined by the following formula: (4.406X2−0.592X+0.021)≤Y≤(0.726X2−0.121X+0.009) where X corresponds to the weight fraction of (i) and Y corresponds to the weight fraction of (ii). Also provided is a method of making an optical article from the polymerizable composition.

The invention discloses a preparation method of 1, 5-hexadiene-3, 4-diol, which is characterized in that acrolein is used as a raw material, and the 1, 5-hexadiene-3, 4-diol is prepared by reductive coupling reaction in the presence of an ammonium chloride aqueous solution and a zinc powder catalyst. According to the method, the yield reaches up to 92% or above, compared with an existing synthesis method, reaction operation is simplified, the reaction yield is increased, and a novel reduction method is provided; the separation and purification method is simple and efficient, the product quality is high, the commercialized use requirement can be met, and large-scale production is achieved.

The invention relates to a staining reagent for carrying out histological and / or hematological stainings, comprising A) at least one solvent in a proportion of 55% by volume to 99.95% by volume, selected from the group consisting of A1) esters of the formula R1-C(=O)-O-R2, A2) ethers of the formula R3-O-R4, A3) sulfoxides of the formula R5-S(=O)-R6, A4) sulfones of the formula R7-S(=O)2-R8, A5) monohydric alcohols in which the alcoholic OH group is bonded to an aliphatic C atom in a hydrocarbon group of 4 to 8 carbon atoms, A6) diols which have 2 OH groups on an aliphatic hydrocarbon radical with 3 to 6 carbon atoms, A7) formals of the formula R9-O-CH2-O-R10, A8) dihydrolevoglucosenone, A9) propylene carbonate, and A10) N-butylpyrrolidone; B) at least one staining pigment in a proportion of 0.05% by volume to 7% by volume; and C) optionally an additional solvent selected from the group consisting of dimethyl sulfoxide, water, monohydric alcohols with 1 to 3 carbon atoms, and sugar alcohols, wherein R1 represents a C4 to C8 alkyl group or a group of the formula R2-O-C(=O)-R-; R2 represents a C1 to C4 alkyl group; R represents a C2 to C6 alkylene group; R3 represents a C2 to C4 alkyl group which can have an OH group; R4 represents a group of the formula -R11-(O-R12-)n-R13; R11 represents a C2 to C4 alkylene group; R12 represents a C1 to C4 alkylene group; R13 represents H, OH or -O-C(=O)-CH3; n represents 0, 1, 2 or 3; and R5 and R6 independently of one another represent a C1 to C4 alkyl group, with the proviso that the sum of the number of carbon atoms in R5 and R6 is 3 or higher, R7 and R8 independently of one another represent a C1 to C4 alkyl group, and R9 and R10 independently of one another represent a C4 to C8 alkyl group.

The invention discloses a hot-melt polyester with high washing resistance, which is prepared from the following raw materials: a binary acid composition, a dihydric alcohol composition, an antioxidant and a catalyst, and the molar ratio of the binary acid composition to the dihydric alcohol composition is 1: (1.8-2.2). According to the invention, the hydrophobicity and structural stability of polyester can be obviously improved, so that the reflective layer is not easy to peel off in the washing process, and good bonding strength and retroreflection coefficient are maintained after washing. The retroreflection coefficient is 180-300 cd.lx <-1 >. M <-2 > and the bonding strength is 1.2-1.8 MPa after the reflective material is washed for 50 times by an ISO 15797-part4 method, so that the reflective material meets the requirements of keeping high washing resistance and high brightness from a common mark to a high-end protective reflective material, and has a wide application prospect.

The invention relates to a polyester material, a preparation method thereof and an antibacterial product. The polyester material comprises a polyester main chain and antibacterial peptide; the polyester main chain is prepared from the following raw materials: dibasic acid and / or dibasic ester and dihydric alcohol; the dibasic acid comprises terephthalic acid, and the dibasic ester comprises terephthalic acid ester; the antibacterial peptide is prepared through a ring-opening polymerization reaction of amino-acid ester-N-carboxy anhydride. According to the polyester material, the heat resistance and the optical performance are further improved while good antibacterial performance is achieved.

The presently claimed invention relates to an alkaline composition for cleaning a substrate comprising i) copper or copper alloy and ii) cobalt or cobalt alloy, the composition comprising: a) at least one pH adjustor selected from diglycolamine, 4,4-diethoxy-N,N-dimethyl-1-butanamine, 3-dimethylaminopropan-1-ol, dimethylaminoethoxyethanol, N,N-dimethylisopropanolamine, ethylethanolamine, N-methyldiethanolamine, 2-(2-(methylamino)ethoxy)ethanol, 3-(methylamino)propane-1,2-diol, 2-[2-[2-(2-methoxy- ethoxy)ethoxy]ethoxy]ethylamine, 2-[2-(2-aminoethoxy)-ethoxy]-ethanol, N-butyldiethanolamine, diisopropanolamine, N-methyldiisopropanolamine, monoethanolamine, 3-dimethylamino-1,2-propandiol, 2- amino-1-butanol, 2-(2-(2-(2-aminoethoxy)ethoxy)ethoxy)ethanol, prolinol, 1-methyl-2-pyrrolidinemethanol, 1-methyl-2-pyrrolidinemethanol, 1-methyl-3-pyrrolidinol, 2-amino-2-methyl-1-propanol, N,N-dimethylethanolamine, butylethanolamine, diethylethanolamine, 3-methoxypropylamine, 4-(2-hydroxyethyl)morpholine, 4-(dimethylamino)cyclohexanol, 2-amino-2-methyl-1, 3-propanediol, or diisopropylamine; b) at least one complexing agent selected from C2 to C12 hydrocarbon having at least two sulfonic acid or carboxylic acid groups; c) at least one polymeric dispersing agent having a weight average molecular weight ≥ 1000 g / mol; and d) a solvent comprising water.

The object of the present invention is to provide a resin composition that is heat-curable or photocurable, alkali-soluble, has a low dielectric constant and dielectric loss tangent of the cured product, and exhibits high adhesion and glass transition temperature, as well as excellent insulation reliability. [Solution] A resin composition is used that contains a compound represented by the following formula (1) and a compound containing one or more epoxy groups in one molecule. TIFF2026103975000012.tif29170 (In formula (1), each X independently represents a residue of an aromatic or aliphatic tetracarboxylic anhydride with the carboxyl group removed. Y represents a divalent residue of a diol with the hydroxyl group removed. Each Z independently represents a residue of a functional group containing a radically polymerizable double bond. n is the average number of repeating units and is a real number between 0.1 and 20.)

Provided is a method for preparing a diol. In the method, a saccharide and hydrogen as raw materials are contacted with a catalyst in water to prepare the diol. The employed catalyst is a composite catalyst comprised of a main catalyst and a cocatalyst, wherein the main catalyst is a water-insoluble acid-resistant alloy; and the cocatalyst is a soluble tungstate and / or soluble tungsten compound. The method uses an acid-resistant, inexpensive and stable alloy needless of a support as a main catalyst, and can guarantee a high yield of the diol in the case where the production cost is relatively low.

Provided is a thermoplastic resin composition having excellent optical characteristics, which does not impair the characteristics of an optical resin composition, has high flowability and good moldability, and has a composition capable of preventing gelation (increase in molecular weight). The polycarbonate resin contains a structural unit (A) derived from a diol represented by formula (1), and a structural unit (B) represented by formula (2) and / or a structural unit (C) represented by formula (3). # imgabs0 #

The application belongs to the technical field of compound preparation, and discloses a preparation method of (1'S, 2'S)-eugenol glycerol 3'-O-beta-D-glucopyranoside. The method is characterized in that: a phenolic hydroxyl group allyl compound protected by a benzyl group is subjected to O-glycosylation reaction with a D-glucopyranosyl donor protected by an acetyl group, so as to obtain an olefin type protected glycoside intermediate which retains a side chain carbon-carbon double bond; then, asymmetric dihydroxylation reaction is performed on the intermediate, so as to construct a target vicinal diol chiral structure; finally, the acetyl protecting group of the sugar hydroxyl group and the benzyl protecting group of the phenolic hydroxyl group are sequentially removed, so as to obtain the target compound. The preparation method of (1'S, 2'S)-eugenol glycerol 3'-O-beta-D-glucopyranoside is characterized in that: the glycoside bond is constructed before dihydroxylation, which is beneficial to reducing the competition reaction of multiple hydroxyl groups and realizing the preparation of the target compound.

The invention discloses a residual acid analysis method for alcohol compounds. The method comprises the following steps: providing an organic solvent, and putting the organic solvent into a distiller to distill the organic solvent and obtain a purified organic solvent in a distillation middle section; mixing a basic inorganic compound with the purified organic solvent to produce a titration liquid; mixing a diol compound with the purified organic solvent to generate a sample to be detected; and carrying out acid-base titration on the to-be-detected sample by using the titration liquid so as to analyze the acid residual quantity of the diol compound. Wherein the equivalent concentration of the alkaline inorganic compound in the titration liquid is not more than 0.005 N. Therefore, the detection accuracy of the residual acid analysis of the alcohol compounds can reach the concentration grade which is low enough, and the detection limit is improved.

The invention discloses a method for producing bio-based dihydric alcohol. According to the method, bio-based methyl 2-tetrahydrofuroate, tetrahydrofurfuryl propionate and methyl 2-(tetrahydrofuran-2-yl) acetate are used as precursors for dihydric alcohol synthesis, Cu-Ga-Mn / SiO2 or Cu-Ga-Mn / SiO2-Al2O3 is used as a hydrogenation catalyst, cyclic ether ester structures are synchronously activated in a fixed bed reactor, ester group hydrogenation and tetrahydrofuran ring opening are synergistically carried out, and the high-purity tetrahydrofuran is obtained. The reaction path is shortened. The hydrogenation catalyst is prepared by combining a sol-gel method and hydrothermal synthesis through roasting and reduction, active components are uniformly distributed, and the hydrogenation catalyst has excellent hydrogenation activity and structural stability.

The utility model relates to dihydric alcohol ether micro -tube type reactor technical field, and disclose a dihydric alcohol ether micro -tube type reactor, including the tubular reactor body, the both sides of tubular reactor body surface all are connected with the connecting port for feeding, the inner chamber of tubular reactor body is provided with the auxiliary block of reinforcement fluid chaos mixing effect, the utility model discloses in the routine use of tubular reactor body, can be under the action of liquid heat exchanger body, pressurizing pump, heat exchange pipe and liquid delivery pipe, the heat of tubular reactor body inner chamber is heat exchanged, reaches the effect of temperature control to reduce the possibility of by -product production in the reaction due to local overheating, and can be under the action of pressurizing pump, can make the pressure change of pressurizing chamber inner chamber, thereby make the vibration piece pressure vibrate, and then reach the effect of vibration and drop viscous material, reduce the probability of tubular reactor body block, improve the practicality of this device.

The invention provides a production method of 4-10B-boric acid-L-phenylalanine with high boron atom utilization rate, which comprises the following steps: A, adding strong base and a Turbo Grignard reagent into a 4-halogenated-phenylalanine derivative for reaction, and then adding glycol ester borane for continuous reaction to obtain a 4-boryl-phenylalanine derivative; and B, carrying out acidic hydrolysis on the 4-boryl-phenylalanine derivative, so as to obtain the 4-10B-boric acid-L-phenylalanine. The boron element is introduced into phenylalanine molecules through halogen-metal exchange and electrophilic substitution reaction, wherein the reagent combination of the Turbo Grignard reagent and the glycol ester borane ensures the efficient proceeding of the boronylation process. The production method disclosed by the invention is mild in reaction condition and simple to operate, has high-level comprehensive yield and 10B boron atom utilization rate, and provides a new way for realizing low-cost commercial production of 10B-BPA.

Provided is a polyester resin containing diol structural units and dicarboxylic acid structural units, in which 1-25 mol% of all the diol structural units are diol structural units (alpha) having a cyclic acetal skeleton, and 15-40 mol% of all the dicarboxylic acid structural units are dicarboxylic acid structural units (beta) derived from isophthalic acid.

The present invention relates to a catalyst comprising coke, characterized in that the coke has at least two peaks at wavelengths between 1450 cm-1 and 1700 cm-1 when analyzed by diffuse reflectance infrared spectroscopy (“diffuse reflectance infrared Fourier transform spectroscopy” - DRIFTS). The aforementioned catalyst comprising coke can be advantageously used in a process for producing dienes, preferably conjugated dienes, more preferably 1,3-butadiene, said process comprising dehydrating at least one enol having at least 4 carbon atoms. Preferably, the enol having at least 4 carbon atoms can be obtained directly from a biosynthetic process or by a catalytic dehydration process of at least one diol. When the enol is butenol, the diol is preferably butanediol, more preferably 1,3-butanediol, even more preferably bio-1,3-butanediol, i.e., 1,3-butanediol derived from a biosynthetic process. When the diol is 1,3-butanediol or bio-1,3-butanediol, the dienes obtained according to the process of the present invention are 1,3-butadiene or bio-1,3-butadiene, respectively.

Provided is a non-aqueous inkjet ink composition and recording method that can achieve both good gloss and good unevenness reduction. A non-aqueous inkjet ink composition according to an embodiment of the present invention contains a luster pigment, and diol monoethers A and B represented by the following formula (1) that differ in flash point, the flash point of the diol monoether A being 85°C or lower, the flash point of the diol monoether B being 95°C or higher, the total content of the diol monoether A and the diol monoether B being 20 to 60% by mass relative to the total amount of the ink composition, and the content of the diol monoether A being greater than the content of the diol monoether B.R1‑(O‑R2) n ‑OH … Formula (1)In formula (1), R1 is an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2 is an alkylene group having 1 to 5 carbon atoms, and n is an integer of 1 to 4.

The present invention provides a condom comprising a copolymer X obtainable by polymerisation of monomers A, B, C, and D;wherein monomer A is one or more compound of the formula:in which R1 and R2 are independently selected from H and C1-C20 alkyl optionally substituted by a hydroxyl, primary amine or secondary amine group, provided that one of R1 and R2 bears a hydroxyl, primary amine or secondary amine group;monomer B is one or more diisocyanate compound of the formula OCN—R3—NCO, in which R3=C4-C20 alkylene, which may optionally be cyclic or branched;monomer C is one or more telechelic hydroxy terminated polyalkylene glycol compound having a number average molecular weight of 1000 to 10,000 and is preferably linear;monomer D is one or more diol of the formula HO—R4—OH, in which R4 is C2-C20 alkylene which may be interrupted by 1-5 heteroatoms selected from the group consisting of O, N and S, preferably 1 O atom and / or preferably wherein R4 is linear;wherein, the molar ratio of monomers D to C is in the range 0.1:1 to 10:1.

Provided is a thermoplastic resin composition with excellent optical properties, having high fluidity and good moldability without compromising properties of optical resin compositions, and having a compositional makeup that can prevent gelatinization (increase in molecular weight). The present invention provides a polycarbonate resin including: a constituent unit (A) derived from a diol represented by the formula (1) below; and a constituent unit (B) represented by the formula (2) below and / or a constituent unit (C) represented by the formula (3) below:

To provide an external preparation composition which secures excellent stability immediately after production and under high-temperature storage, enhances skin compatibility during application, reduces a sticky sensation on skin after application, and further has a transparent or semi-transparent appearance.SOLUTION: An external preparation composition comprises the following components (A), (B), (C), (D), and (E): (A) at least one selected from sphingosine and derivatives thereof; (B) a dihydric alcohol; (C) a compound having a carboxyl group and having 7 or fewer carbon atoms; (D) an oily agent that is solid at 25°C; and (E) water.SELECTED DRAWING: None

A hydrophilic compound is formed by reacting an esterified itaconic acid with an unsaturated organic acid or an unsaturated organic alcohol through a free radical reaction. The esterified itaconic acid is formed by reacting an itaconic acid with a C4-12 linear diol through an esterification reaction. The unsaturated organic acid is CnH2n-x(COOH)x, wherein n is an integer of 2 to 8, and x is an integer of 1 to 3. The unsaturated organic alcohol is CmH2m-y(OH)y, wherein m is an integer of 3 to 8, and y is an integer of 1 to 3.

To provide a thermosetting composition which has good storage stability and exhibits good low-temperature curability when formed into a resin film.SOLUTION: A thermosetting composition contains a blocked polyisocyanate component, a monohydric or dihydric alcohol compound, and a polyol. The blocked polyisocyanate component contains a blocked polyisocyanate compound having a constituent unit represented by formula (I). In the formula, R11-R13 each independently represent an alkyl group which may contain one or more kinds of substituents selected from the group consisting of a hydroxy group and an amino group; the total number of carbon atoms of R11-R13 is 4 or more and 20 or less; R14-R16 each independently represent a hydrogen atom or an alkyl group which may contain one or more kinds of substituents selected from the group consisting of a hydroxy group and an amino group; and a wavy line represents a bond.SELECTED DRAWING: None

This invention provides a method for manufacturing a fluoropolymer with minimal deviation in weight-average molecular weight per batch. The method for manufacturing the fluoropolymer of this invention is characterized by comprising the following steps: a fluoropolymer synthesis step, wherein a diol represented by formula (3) is reacted with at least one selected from unsaturated carboxylic acids, esters of the unsaturated carboxylic acids, acyl halides of the unsaturated carboxylic acids, and anhydrides of the unsaturated carboxylic acids to obtain a composition comprising a fluoropolymer represented by formula (4) as the main reactant and a fluoropolymer represented by formula (5) as a by-reactant; a fluoropolymer purification step, wherein the fluoropolymer represented by formula (5) is removed from the composition, and the content of the fluoropolymer represented by formula (5) is 1500 ppm or less, expressed as a mass fraction (parts per million) based on the fluoropolymer represented by formula (4); and a polymerization step, wherein the composition after the fluoropolymer purification step is subjected to a polymerization reaction to produce a fluoropolymer comprising a repeating unit represented by formula (1) and a repeating unit represented by formula (2). In equations (1), (2), (3), (4), and (5), R 1 R 2 Each of the following is independently a hydrogen atom, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, or tert-butyl, R 3 R 4 Each is independently a hydrogen atom, methyl or ethyl, R 5 R is a hydrogen atom or a trifluoromethyl group. 6 It can be a hydrogen atom, a chlorine atom, a methyl group, or a trifluoromethyl group.