207 results about "Dimethylamines" patented technology

The invention relates to the technical field of chemical synthesis, and discloses a preparation method of anhydrous N, N-dimethyl amino sulfuryl fluoride, which comprises the following steps: (1) introducing sulfuryl fluoride gas into a dimethylamine organic solution to carry out nucleophilic substitution reaction, and then adding triethylamine to obtain a mixed solution containing N, N-dimethyl amino sulfuryl fluoride; and (2) sequentially carrying out normal-pressure rectification and reduced-pressure rectification on the mixed solution containing the N, N-dimethyl amino sulfonyl fluoride to obtain the N, N-dimethyl amino sulfonyl fluoride. According to the method, water is not introduced in the whole process, the risk of water residue is avoided, and the prepared product is high in yield and purity.

The invention discloses an anticorrosive coating composition based on a nano hybrid and a preparation method of the anticorrosive coating composition, and relates to the technical field of powder coatings. Comprising the following components in parts by weight: 60-70 parts of fluorosilicone modified epoxy resin, 8-10 parts of an aminoethylated acrylic polymer, 4-8 parts of a functionalized nano hybrid, 4-6 parts of a curing agent, 0.3-1.2 parts of an accelerant, 1-2 parts of benzoin, 2-4 parts of a functional aid, 10-15 parts of a micron-sized filler and 1-2 parts of a coupling agent. The curing agent is prepared by compounding dicyandiamide, bicyclo [2.2. 1] heptane dimethylamine and 3, 5-diamino-1, 2, 4-triazole according to a mass ratio of (3 to 5): 1: (0.8 to 1.2). The coating composition is high in adhesive force and excellent in impact resistance and corrosion resistance.

The present application relates to a kind of dimethylamine piperidine continuous synthesis dimethylamine piperidine method of oxy group, by using reaction raw material mixed solution into continuous flow packed bed reaction zone, i.e.catalyst layer;Reaction temperature is 20-80 ℃, normal pressure, feed liquid is the mixture of dimethylamine piperidine, hydrogen peroxide and deionized water, oxidation is carried out on the catalyst layer of continuous flow packed bed adiabatic reactor to make dimethylamine piperidine into dimethylamine piperidine oxy group, realize the continuous preparation of dimethylamine piperidine oxy group;The obtained reaction liquid is quenched, then filtered to remove solid particle quenching agent, vacuum distillation to remove water and vacuum rectification treatment obtain high-purity dimethylamine piperidine oxy group;The process scheme overcomes the series of deficiencies in the previous preparation process, such as complicated steps, low product purity, low production capacity in unit production time, realizes the continuous preparation of high-purity dimethylamine piperidine oxy group, with the characteristics of efficient, safe, green manufacturing.

The present application belongs to the technical field of protective coating, and relates to a protective coating with reverse enhanced adhesion, a preparation method and application thereof. The protective coating is composed of component A and component B. The preparation raw materials of component A include water-based epoxy resin emulsion, cashew phenol glycidyl ether, wetting penetrant and defoaming agent. The preparation raw materials of component B include phenolic amine curing agent, alicyclic amine curing agent, dopamine, 2,4,6-tris(dimethylaminomethyl)phenol and pigment filler. The dopamine and the phenolic amine curing agent and the alicyclic amine curing agent are grafted under the action of 2,4,6-tris(dimethylaminomethyl)phenol to form a modified curing agent. The coating has low requirements for surface treatment, high adhesion in dry and humid environments and presents the characteristics of "reverse enhanced adhesion".

This invention discloses a highly efficient catalytic synthesis process for nicotinamide intermediates using the field of organic synthesis technology. The process includes: adding appropriate amounts of dichloronicotinic acid, organic solvent, lanthanum-doped composite metal fluoride-diatomaceous earth supported catalyst, and encapsulated 4A molecular sieve to a reaction vessel under nitrogen protection; purging with nitrogen, heating, and stirring; introducing anhydrous dimethylamine gas, controlling the pressure, and continuing stirring; after the reaction is complete, washing with sodium bicarbonate aqueous solution, washing with deionized water, drying, concentrating, and recrystallizing to obtain the target product. The lanthanum-doped composite metal fluoride-diatomaceous earth supported catalyst prepared by this invention is recyclable, has mild reaction conditions, high product yield, is environmentally friendly, and suitable for industrial production.

The present invention relates to ophthalmic formulations in which a synergistic combination of three different types of disinfectants (a polybiguanide compound, a quaternary ammonium compound and an antifungal / anti-acanthamoeba compound), in particular a combination of polyhexamethylene biguanide, polyquaternium-1 and myristoylaminopropyl dimethylamine, high concentrations of hyaluronates are enabled to provide better comfort and support for corneal health without compromising antimicrobial efficacy. The novel ophthalmic formulations support the use of hyaluronates at concentrations greater than 7.5 times as high as currently commercially available multi-purpose disinfectants.

The present application belongs to the technical field of pharmaceutical therapy, and particularly relates to an amide-substituted tryptophan ketone derivative, a preparation method and application thereof. The structural formula of the tryptophan ketone derivative is shown in formula (A) or formula (B). In the formula, n=1 or 2, and R is any one of dimethylamine group, diethylamine group, morpholine group, 1-methylpiperazine group, cyclopropylamine group and 4-hydroxypiperidyl group. The compound can selectively inhibit the activity of acetylcholinesterase, and has the potential to develop into a drug for treating Alzheimer's disease due to the abilities of self-aggregation and the like. 1‑42 ​

The invention relates to a method for preparing (cyclopentadienyl) tris (dimethylamino) hafnium by using nuclear magnetic control, which comprises the following steps: S1, carrying out heating reflux reaction on hafnium tetrachloride, cyclopentadiene and dimethylamine in the presence of n-butyllithium and n-hexane, and after reacting for a certain time, taking supernate to detect a nuclear magnetic hydrogen spectrum; s2, calculating the ratio a of the integral area of the characteristic peak A to the integral area of the characteristic peak B according to the nuclear magnetic hydrogen spectrum, judging whether a is in a target range or not, if a is in the target range, terminating the reaction, separating a liquid phase, distilling and collecting a crude product; and if a value is greater than the maximum value of the target range, adding cyclopentadiene into the reaction system to continue the reaction, and if a value is less than the minimum value of the target range, continuing the reaction until the ratio of the integral area of the characteristic peak A to the integral area of the characteristic peak B in the nuclear magnetic hydrogen spectrum of the reaction supernatant is within the target range, terminating the reaction, separating the liquid phase, distilling and collecting a crude product. The method can effectively improve the safety of the production process, the raw material conversion rate and the product purity.

The invention belongs to the field of electrochemical synthesis, and particularly discloses a method for synthesizing N, N, N ', N'-tetramethyl methylenediamine by directly utilizing a dimethylamine aqueous solution through electrochemical amine methylenation. According to the method, a dimethylamine aqueous solution is used as a raw material, and an electrochemical amine methyleneation reaction of dimethylamine is carried out on an anode loaded with a carbon material catalyst in an electrically driven oxidation manner, so that synthesis of N, N, N ', N'-tetramethyl methylenediamine is realized. Different from the existing dimethylamine and formaldehyde condensation method and dimethylamine and methanol electrosynthesis method, the method disclosed by the invention directly adopts the industrial dimethylamine aqueous solution as a raw material to synthesize N, N, N ', N'-tetramethyl methylenediamine, so that the process flow is simplified, and the yield is high. The method has the characteristics of mild process conditions, high system stability, few byproducts, greenness, safety, low cost and suitability for industrial application. The method has wide application potential in the fields of electrochemical organic synthesis, energy storage, pharmaceutical chemical industry and the like.

The invention belongs to the technical field of chemical synthesis of semiconductor materials, and particularly relates to a synthesis method of tetra (dimethylamino) titanium, which comprises the following steps: (1) reacting titanium tetrachloride with dimethylamine to generate an intermediate TiClx [N (CH3) 2] 4-x, where x is an integer from 0 to 4; (2) reacting dimethylamine with an organic metal lithium reagent to synthesize lithium dimethylamino (LiN (CH3) 2); and (3) reacting the intermediate obtained in the step (1) with lithium dimethylamino obtained in the step (2) to obtain tetra (dimethylamino) titanium. By adopting a step-by-step reaction strategy, the dependence on expensive n-butyllithium is fundamentally reduced, the raw material cost is remarkably reduced, meanwhile, the reaction process is optimized by generating an intermediate, the product yield is greatly improved, the generation of byproducts is effectively reduced, and the product purity is improved.

The application discloses a preparation and purification process of high-purity low-chlorine tetra (dimethylamino) tin, and belongs to the technical field of synthesis of semiconductor electronic chemicals. The three core technologies of accurate control of the molar ratio of chlorine and tin 2.00-2.05, low-temperature segmented synthesis of intermediates at-78 DEG C to-60 DEG C, and three-stage gradient low-temperature purification at 40 DEG C to 60 DEG C are used to synthesize the product with high-purity anhydrous stannous chloride and low-moisture anhydrous dimethylamine as raw materials, and double alkali reagents are used to synthesize the product, so that the risk of high-temperature decomposition is avoided in the whole process, and chlorine ions and metal impurities are deeply removed. The product has a purity of greater than or equal to 99.99%, chlorine ions are less than 10 ppm, single metal impurities are less than 1 ppm, total metal impurities are less than or equal to 5 ppm, moisture is less than 20 ppm, and the comprehensive yield is 55%-60%. The product is suitable for EUV dry photolithography, electron beam CVD and tin-based ALD processes. The process parameters of the application are quantitatively controlled in a narrow range, the technical barriers are strict, and the application has a good authorization prospect.

The present invention relates to ophthalmic formulations wherein a synergistic combination of three different classes of disinfectants (a multimeric biguanide compound, a quaternary ammonium compound and an antifungal / anti-acanthamoeba compound, in particular a combination of polyhexamethylene biguanide, Polyquaternium-1 and myristamidopropyl dimethylamine) enables the use of high concentrations of hyaluronate for providing better comfort and support of corneal health without compromising antimicrobial efficacy. The novel ophthalmic formulations support the use of more than 7.5 times higher concentrations of hyaluronate than are present in currently marketed multi-purpose disinfection solutions.

The application provides a nitrogen-doped carbon-coated catalyst, a preparation method thereof and a method for preparing m-xylylenediamine from m-xylylene cyanide, the nitrogen-doped carbon-coated catalyst is a core-shell structure with a metal active component as an inner core and a nitrogen-doped carbon material as a coating layer, and the loading amount of the metal active component is 9-50 wt% based on 100 wt% of the mass fraction of the nitrogen-doped carbon-coated catalyst. The nitrogen-doped carbon-coated catalyst provided by the application does not need to be activated and can directly be used to show excellent catalytic activity, selectivity and stability for the hydrogenation reaction of m-xylylene cyanide, the selectivity and yield of m-xylylenediamine can be significantly improved under relatively mild reaction conditions, and the catalyst is easy to separate from the product and convenient for recycling.

The invention relates to the field of textile printing materials, and discloses a preparation method of water-based digital printing bottoming white adhesive cement, which comprises the following steps: mixing water-based acrylate emulsion with an auxiliary agent and a macromolecular quaternary ammonium salt color fixing agent to obtain a premix; mixing the premix with filling powder to obtain dispersion liquid; and adding a curing agent and a thickening agent into the dispersion liquid and mixing. The macromolecular quaternary ammonium salt color fixing agent is prepared by reacting an organic silicon modified allylamino phosphorus-containing bromine substituent and bis (dimethylamino) phosphoric acid hydrogenated cardanol ester; the organic silicon modified allylamine phosphorus-containing bromine substituent is prepared by preparing the allylamine phosphorus-containing bromine substituent from allylamine, phenyl dichlorophosphate and 2-bromoethylamine hydrobromide as raw materials and then reacting the allylamine phosphorus-containing bromine substituent with heptamethyltrisiloxane. The white rubber cement prepared by the preparation method is bright in color and clear in pattern, can be recycled and reused, and has the advantages that the white rubber cement is easy to prepare, the cost is low, and the application prospect is wide. The color fixing fastness, the flame-retardant and fire-proof performance, the net blocking prevention performance and the hand feeling comfort degree are good.

The invention discloses a method for high-selectivity separation of low-concentration coal bed gas by a hydrate method using tri-n-butylphosphine oxide as a thermodynamic accelerant. The method comprises the following steps: carrying out hydrate generation and separation on low-concentration coal bed gas in a 5 wt% tri-n-butyl phosphine oxide solution under the conditions of 277.15 K and 4 MPa, and increasing the methane concentration from 30.07 mol% to 88.17 mol% after purification; the separation performance is improved by further adding 0.5 wt% of a kinetic accelerator (preferably cocamidopropyl dimethylamine), and experimental results show that the methane concentration after single-stage separation can be improved from 30.07 mol% to 92.84 mol%, the separation factor reaches 40.93, and the system is in slurry dispersion and has no wall climbing phenomenon. The method is safe to operate, the accelerant can be recycled, and the method is suitable for efficient purification and resource utilization of methane in mixed gas such as low-concentration coal bed gas, biogas and coke-oven gas.

The invention discloses a wound repair material and a preparation method thereof, and relates to the technical field of medical materials. The wound repair material is prepared from the following raw materials in parts by weight: 50 to 60 parts of bioactive glass, 15 to 30 parts of chitosan, 10 to 20 parts of functional materials and 300 to 450 parts of deionized water. The preparation method comprises the following steps: reacting oleamide propyl dimethylamine with 4-chlorobutanol to generate an intermediate 1, reacting the intermediate 1 with 5, 10, 15, 20-tetra (4-carboxyl phenyl) porphyrin to generate an intermediate 2, and reacting the intermediate 2 with 4, 4 '-{[6-((1-carboxyl-2-mercaptoethyl) amino)-1, 3, 5-triazine-2, 4-diyl] bis (nitrounit)} bis [4-(2-carboxyethyl) pimelic acid] under the action of a photoinitiator to generate the functional material. The wound repair material prepared by the invention has excellent antibacterial property and hemostatic property.

1. The name of the design product: label (2, 4-dimethylamine salt). 2. The use of the design product: for product packaging. 3. The design points of the design product: in the combination of shape and pattern. 4. The picture or photo that best indicates the design points: front view. 5. The design product is a flat product, omitting the left view, right view, top view, bottom view; the back of the design product is a part that is not easily visible or not visible during use, omitting the rear view.

A treatment article comprising a fiber, a sizing agent, and a retention aid. The sizing agent comprises a wax or component thereof having an acid value of 10 mg to 220 mg KOH / g as measured according to USP 401. The retention aid comprises a nitrogen-containing polymer independently selected from the group consisting of (i) a nitrogen-containing polymer of Formula I, (ii) a polyethyleneimine, (iii) a polyaminoamide, (iv) a copolymer formed from the reaction product of epichlorohydrin and dimethylamine, and (v) combinations thereof.

The application discloses a preparation method of relugolix and belongs to the field of drug synthesis. The method uses 2-[(2,6-difluorobenzyl) n-propoxy amido]-4-(dimethylamino) methyl-5-(4-nitrophenyl) thiophene-3-carboxylic acid ethyl ester (formula II) as a starting material, and relugolix is prepared through the following steps: inorganic base hydrolysis, amide condensation, inorganic base cyclization, 10% Pd / C catalytic hydrogenation, and finally amide condensation with methoxyamino carbonic acid phenyl ester. The starting material used in the preparation method is cheap and easy to obtain, the reaction is mild, the operation is simple, the product has high purity and high yield, no biuret by-product is detected, and the method is suitable for industrial production.

The invention discloses a method for synthesizing ziram. The method comprises the following steps: S1, stirring a compound surfactant and zinc oxide to obtain a dispersion liquid; s2, sealing and pressurizing, and adding dimethylamine for reaction to obtain a dimethylamine salt mixture; and S3, dropwise adding carbon disulfide, performing condensation reaction, and removing impurities to obtain the ziram, wherein the compound surfactant contains at least one of a nonionic surfactant, an anionic surfactant or a macromolecular surfactant. According to the method, the efficient and green synthesis of the ziram is realized through the synergistic effect of a compound surfactant system, a sealed pressurized reaction and a progressive charging sequence.

The application provides an organic-inorganic hybrid zirconium-based polyacid derivative, which has a molecular formula of [H2N(CH3)2]4[Zr(DL-tartH)2(SbW 10 H8[Zr(DL-tartH)2(SbW 17 )2]·36H2O. 58 The zirconium-based polyacid derivative is prepared by mixing DL-tartaric acid, sodium tungstate, dimethylamine hydrochloride, Na9[SbW9O 33 ]·19.5H2O and ZrOCl2·8H2O in water in a certain proportion and reacting under water bath conditions. The application explores the photochromic process under the irradiation of a 300W xenon lamp, the discoloration process after the photochromic process under the conditions of room temperature, 50±5 DEG C and 80±5 DEG C respectively, and the discoloration process of the photochromic process under different oxygen concentrations. It is found that the mechanism of the photochromic process is mainly caused by W 6+ →W 5+ charge transfer, and the zirconium-based polyacid derivative can be used as a photochromic material, especially a reversible photochromic material. The target product 1 is dissolved in distilled water and coated on cellulose filter paper, and the xenon lamp coloring can show obvious blue color, realizing inkless printing.

The invention provides tri (dimethylamino) cyclopentadienyl cerium as well as a preparation method and application thereof. The tri (dimethylamino) cyclopentadienyl cerium provided by the invention combines the spatial stability of a cyclopentadienyl ligand and the high reaction activity of a dimethylamino ligand, has appropriate volatility and lower thermal decomposition temperature, and is a cerium-based precursor with great potential. The preparation method of the tri (dimethylamino) cyclopentadienyl cerium provided by the invention has a better target product yield. The cerium-based precursor provided by the invention is tris (dimethylamino) cyclopentadienyl cerium, and has a structural formula shown in the specification.

The invention belongs to the technical field of chemical separation and purification, and particularly relates to a purification process of trimethylamine. The invention aims to solve the problem of insufficient purity of the current trimethylamine product, especially the technical problems that the content of monomethylamine and dimethylamine exceeds the standard and the peculiar smell is obvious. Mesoporous silica gel subjected to sulfonyl chloride derivative surface functionalization modification is used as a selective adsorbent and is subjected to a contact reaction with a raw material trimethylamine, and monomethylamine and dimethylamine impurities are selectively removed; then carrying out catalytic hydrogenation on trimethylamine and a small amount of hydrogen together through a loaded metal catalyst, so that oxides in trimethylamine are reduced into trimethylamine and water; and finally, carrying out deep dehydration and purification on the product by using a high-hydrophilicity membrane by adopting a pervaporation membrane separation technology to obtain a high-purity trimethylamine product.

The utility model discloses a tail gas absorption tower, which relates to the technical field of tail gas treatment and comprises an absorption tower body, a gas outlet and a gas inlet, the gas outlet and the gas inlet are respectively positioned at the upper end and the lower end of the absorption tower body, and a water washing unit, a methanol washing unit and a dust removal unit are sequentially arranged in the absorption tower body from top to bottom. The dust removal bag is used for separating the filter chamber from the methanol washing unit; and the air inlet is communicated with the filter chamber. According to the utility model, alcohol washing and water washing are integrated in one absorption tower, so that methanol, ammonia, monomethylamine, dimethylamine, trimethylamine and the like generated in the methylamine production process are absorbed, the occupied area of the absorption tower can be reduced, and the tail gas treatment efficiency of the absorption tower is improved.

The application relates to a kind of lipid nanocarriers coupled with GO-203 and loaded with DMAMCL and its preparation method and application, belong to the field of biological medicine and nano-preparation.The lipid nanocarriers include water phase core, lipid bilayer and surface modification layer from inside to outside, wherein water-soluble dimethylamine methyl chloride (DMAMCL) is loaded in the water phase core;The lipid bilayer is wrapped in the water phase core, and coumarin-6 is embedded as fluorescent marker for tracing and detection;Functional modification layer is arranged on the outer surface of the lipid bilayer, including DSPE-PEG2000-COOH and DSPE-PEG2000-GO-203, wherein GO-203 is cell membrane penetrating peptide.The lipid nanocarrier provided by the application can realize the synergistic delivery of GO-203 and DMAMCL, be used for regulating tumor immune microenvironment and be used for the treatment of triple-negative breast cancer.

The invention discloses a copper-catalyzed aryl aldehyde ortho-position direct C-H etherification method, which comprises the following steps: by taking aryl aldehyde as a raw material, adding alcohol or phenol as shown in a formula (II), a copper catalyst, a guiding group, alkali and a solvent into a reactor, and reacting in an argon gas atmosphere to prepare an aryl ether compound as shown in a formula (III), a substituent group R1 is hydrogen, methyl, trifluoromethyl, methoxyl, phenyl, iodo, isopropyl, trimethylsilyl, dimethylamino, fluoro, chlorine, ester, tourmaline, naphthyl, isoquinolyl, benzothienyl or phenanthryl; a substituent group R2 is hydrogen, methyl, trifluoromethyl, methoxyl, phenyl, iodo, isopropyl, trimethylsilyl, dimethylamino, fluoro, chlorine, ester, tourmaline, naphthyl, isoquinolyl, benzothienyl or phenanthryl; and a substituent group R2 is methyl, 4-fluorophenyl, cyclobutane methyl, 4-tert-butyl phenyl, pentafluorophenyl, 4-cyanophenyl, 4-methyl ester phenyl, 3-nitrophenyl, adamantane methyl, cyclohexyl or an oestrone analogue. The copper catalyst and amino acid which are low in cost and easy to obtain are used as guiding groups, the operation process is simple and efficient, and the corresponding aryl ether compound can be obtained with the good yield.

The application discloses a self-emulsifying polyether amine curing agent and a preparation method and application thereof, and belongs to the field of high polymer materials. According to the application, components A-F are composed of polypropylene glycol or polytetrahydrofuran glycol with a molecular weight range of 800-2000, component B is selected from at least one of isophorone diamine, dicyclohexyl methane diamine or xylylenediamine, component C is at least one of epoxy derivatives containing long-chain alkyl and aromatic ring structures, component D is polyethylene glycol monomethyl ether amine with a polymerization degree range of 2-5 or an amine compound containing a sulfonic acid group, component E is a tertiary amine compound, and component F is at least one of a hindered phenol antioxidant and a phosphite antioxidant. The curing agent is reliably enhanced in reaction activity at normal temperature, the nucleophilic activity of terminal amino groups is significantly improved while excellent water dispersibility is maintained, and thus the curing rate at normal temperature is greatly accelerated.

This application discloses a dimethylamine salt reactor, belonging to the field of reactor technology. It mainly includes: a fixed frame; a reactor mounted on the upper end of the fixed frame, the reactor having a discharge pipe; an anti-clogging mechanism mounted on the discharge pipe, the anti-clogging mechanism including: a spring mounted on the fixed frame; a filter box mounted on the other end of the spring; a flexible hose mounted on the discharge pipe, the other end of the hose connected to the filter box; a vibration motor mounted on both sides of the filter box; a filter plate inclinedly disposed inside the filter box; an outlet mounted at the lower end of the filter box; and a slag discharge port located on one side of the filter box. The dimethylamine salt reactor of this application, by incorporating the anti-clogging mechanism, achieves the effect of preventing clogging.

This invention relates to the field of alkali metal-chlorine secondary battery technology, and discloses an electrolyte additive, an electrolyte, and an alkali metal-chlorine secondary battery. The additive contains components A, B, and C in a mass ratio of 1:0.2-2.0:0.5-3.0; component A is selected from at least one of ethyl viologen dibromide, benzyl viologen diiodide, and 1,4-phenylenediamine hydroiodate; component B is selected from at least one of 3-(4-iodophenyl)-3-(trifluoromethyl)-3H-bisacrylidine, 1-bromo-2-fluorobenzene, and 4-(benzyloxy)-1-bromo-2-fluorobenzene; and component C is selected from at least one of 3-(trifluoromethyl)phenyltrimethylammonium bromide, (3-fluoro-4-iodophenyl)methylamine, and 3-iodobenzylamine. The electrolyte provided by this invention, when applied in an alkali metal-chlorine secondary battery system, exhibits high reversible capacity, cycle stability, and environmental adaptability.

The application belongs to the technical field of organic synthesis, and specifically discloses a preparation method of dimethyl diallyl ammonium chloride, which comprises the following steps: under the condition that water exists, dimethylamine, an alkaline carrier and allyl chloride are mixed and subjected to a contact reaction to obtain a crude tertiary amine; the alkaline carrier comprises a carrier body and a carbonic acid alkali metal salt loaded on the carrier body; under the condition that an organic solvent exists, the crude tertiary amine and allyl chloride are mixed and subjected to a contact reaction. The method can effectively reduce the hydrolysis of allyl chloride and the generation of dimethylamine hydrochloride in the reaction process, the dimethyl diallyl ammonium chloride product contains almost no other hydrochloride impurities, and the reaction efficiency, the yield and the purity of the dimethyl diallyl ammonium chloride are improved.