L-alanine is an organic compound with molecular formula CthreeHsevenNOtwo, colorless to white crystalline powder, soluble in waterethanol, insoluble inEtherandacetone。It is mainly used for biochemical research, tissue culture, liver function test, flavor enhancer, can increase the seasoning effect of condiments, and can also be used as an acid taste corrector to improveOrganic acidSour taste.[3]
Chinese name
L-Alanine
Foreign name
L-Alanine
Alias
2-Aminopropionic acid
chemical formula
CthreeHsevenNOtwo
molecular weight
eighty-nine point zero nine
CAS login number
56-41-7
EINECS login number
200-273-8
Melting point
297 ℃
Water solubility
Soluble in water and ethanol, insoluble in ether and acetone
1. Propionic acid chlorination ammoniation method: Propionic acid is used as the raw material, under the presence of 3% red phosphorus catalyst at 105 ℃, liquid chlorine is introduced for chlorination to generate 2-chloropropionic acid, and then enters the ammonia solution, with urotropine as the catalyst, ammoniation is carried out at 60 ℃ to generate 2-aminopropionic acid.Finally, the reactant is sent into methanol solution for crystallization and centrifuged;DryAlpha alanineFinished products.2. The α - bromopropionic acid is chlorinated into α - bromopropionic acid;Ammonia;Ammonium bicarbonateMix, stir and reflux for 7h, then evaporate to dryness, soak and wash away ammonium bromide with ethanol, filter out crystals, decolorize and filter, add ethanol to obtain crystals, filter and dry to obtain finished products.3. Acetaldehyde by cyanohydrin method reacts with hydrocyanic acid to produce cyanohydrin, and then reacts with ammonia to obtain aminonitrile;Then, it is hydrolyzed to produce sodium aminopropionate under alkaline conditions, and L-alanine is obtained through ion exchange.
2. MainlyL-aspartic acidAs the raw material, the finished product is obtained through decarboxylation, enzyme killing, decolorization, filtration, crystallization, centrifugation, washing and drying.
3. Enzymatic method
4. Immobilized enzyme
5. Acrylonitrile method Acrylonitrile reacts with ammonia in diphenylamine and tert butyl alcohol solution at 109 ℃ and 1176.798KPa to generate β - aminopropionitrile:sodium hydroxideReact to generate sodium β - aminopropionate: finally acidify with hydrochloric acid to generate β - aminopropionic acid:
sixβ - aminopropionitrileThe method is obtained by hydrolysis and acid precipitation of β - aminopropionitrile
7. Tobacco: BU, 21;FC，20。The acid hydrolysis of silk fiber (degummed white silk) was used in the experiment.
8. Orthogonal crystals obtained from water.
purpose
Announce
edit
medicine
L-alanine is an important raw material for the synthesis of VB6, and it is one of the components of the nutrient "Essence Supplementing Amino Acid Nutrition Infusion".
CysteineIt is mainly used for liver medicine, antidote, expectorants and other medical drugs.
Cysteine and its derivatives can be used for detoxification of liver poisoning, antipyretic analgesia, ulcer treatment, fatigue recovery, infusion and comprehensive amino acid preparations, especially for expectoration;treatmentbronchitisAnd resolving phlegm.
Amino Acid Injection-800, which is mainly composed of L-alanine, is mainly used to treat liver and brain diseases, promote the patients with liver coma to recover quickly, and is also a good diuretic.
food additives
(1) It can improve the nutritional value of food, such as bread, ice-cream, fruit tea, dairy products, carbonated drinks, ice-cream, etc.Adding 0.1~1% alanine can significantly improve theProtein utilizationAnd because alanine can be directly absorbed by cells, it can quickly recover fatigue and stimulate spirit after drinking.
(2) Improving the taste of synthetic sweeteners can increase the sweetness and reduce the dosage.Adding 1~10% alanine to the compound sweetener can improve the sweetness and taste as soft as the natural sweetener, and improve the taste.
Alanine is also one of the raw materials for the synthesis of alitame (L-asparagine-D-alanamide, 600 times the sweetness of sucrose) with high sweetness.
Biochemical research.Tissue culture.Liver function test.
Used as a flavor enhancer.It can increase the seasoning effect of condiments;It can also be used as an acid taste corrector to improve the sour taste of organic acids.
β - alanineIt is used as an additive for electroless plating and electroplating, and also for the preparation of electroplating inhibitor.
extraction process
Announce
edit
Fermentation extraction process
technology roadmap
The extraction process of L-alanine produced by fermentation is shown in the figure below.The fermentation broth is ultrafiltration to remove bacteria and macromolecular proteins, and then adjust a certain pH and flow rate to pass the 732 typeStrongly acidic cation exchange resin(H+type), L-alanine is exchanged to the resin, most of the pigments, soluble proteins and anions in the fermentation broth are discharged with the overflow wastewater, then the L-alanine on the resin is completely eluted with 4% ammonia, and the L-alanine finished product is obtained through the steps of decompression and ammonia removal, activated carbon decolorization, concentration and crystallization, centrifugation, drying, etc.The refined mother liquor separated by centrifugation can be recycled to effectively improve the extraction yield[1]。
Inspection method
Announce
edit
（GB 25543－2010）
Warning
Some of the test procedures specified in the test method may lead to hazardous situations.The operator shall take appropriate safety and protective measures[2]。
general provisions
Unless otherwise specified, only reagents confirmed as analytically pure and Grade III water specified in GB/T6682-2008 shall be used for analysis.The standard titration solution, standard solution for impurity determination, preparations and products used in the test method shall be prepared according to GB/T 601, GB/T 602 and GB/T 603 unless other requirements are specified.
Ninhydrin solution: 20g/L.Weigh 20.0g ninhydrin trione, dissolve it in water, and dilute it to 1000mL.
Sulfuric acid solution: 1+30.
Analysis steps
Ninhydrin test
Weigh about 1gLaboratory samples, accurate to 0.1g, dissolve in 1000mL water, take 5mL of this solution, add 1mL of ninhydrin trione solution, heat to boiling, and turn purple after about 3min.
Oxidation test
Weigh about 0.2g of laboratory sample, dissolve it in 10mL of sulfuric acid solution, add 0.1g of potassium permanganate, and boil it. It will strongly stimulate the generation of malodorous acetaldehyde.
Determination of L-alanine content
Method summary
The sample uses formic acid as cosolvent, glacial acetic acid as solvent, crystal violet as indicator, titrate with perchloric acid standard titration solution, and calculate the content of L-alanine according to the volume of perchloric acid standard titration solution consumed.
Reagents and materials
Glacial acetic acid.
Anhydrous formic acid.
Perchloric acid standard titration solution: c (HClO4)=0.1 mol/L.
Crystal violet indicator solution: 2g/L.
Analysis steps
Weigh about 0.2g of dry substance A in A.5, accurate to 0.0001g, place it in a 250mL dry conical flask, add 3mL of anhydrous formic acid to dissolve it, add 50mL of glacial acetic acid, add two drops of crystal violet indicator solution, titrate with perchloric acid standard titration solution until the solution turns from blue to blue-green as the end point.
At the same time of determination, follow the same steps as the determination, and use the same amount of reagent solution without adding test materialBlank test。
Result calculation
formula
The mass fraction of L-alanine (C3H7NO2) w1, expressed in%, is calculated according to the formula:
Where:
V1 - volume of perchloric acid standard titration solution (A.4.2.3) consumed by the test sample, in milliliter (mL);
V2 -- volume of perchloric acid standard titration solution consumed in blank (A.4.2.3), in milliliter (mL);
C -- accurate value of perchloric acid standard titration solution concentration, in mol/L;
M - value of sample mass, in gram (g);
M - molar mass of L-alanine, in grams per mole (g/mol) (M=89.09).
Take the arithmetic mean of two parallel determination results as the report result.The absolute difference between the two parallel determination results is not more than 0.3%.
Determination of drying loss
According to GB/T6284.During determination, weigh 1g~2g of laboratory sample to 0.0001g.Take the arithmetic mean of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not be greater than 0.03%.Retain part of the dry matter (this is dry matter A) for the determination of L-alanine content.
Determination of pH
According to GB/T 9724.During determination, weigh about 5g of laboratory sample, accurate to 0.01g, and add about 20mLcarbon dioxideDissolve and dilute to 100mL of water, and then conduct the determination.
Determination of arsenic
According to GB/T 5009.76 arsenic stain method.During determination, weigh about 1g of laboratory sample, accurate to 0.01g.Preparation of limited standard solution: pipette 1.00mL of arsenic limited standard solution (containing 0.001mg arsenic), and treat it with the sample at the same time.
Determination of heavy metals
Reagents and materials
ThioacetamideSolution: Weigh about 4g of thioacetamide, accurate to 0.1g, dissolve it in 100mL of water, and store it in refrigerator.Before use, take 1.0mL of this solution and add 5mL of mixed solution consisting of 15mL of sodium hydroxide solution (40g/L), 5mL of water and 20mL of glycerine, place it in a water bath and heat it for 20s, cool it and use it immediately.
CO2 free water.
Ammonium acetate buffer solution, pH=3.5: weigh 25.0g of ammonium acetate, dissolve it in 25mL of water, add 45mL of 6mol/L hydrochloric acid, adjust pH=3.5 with dilute hydrochloric acid or dilute ammonia, and dilute it with water to 100mL.
Lead (Pb) standard solution: 1 μ g/mL.This solution is prepared before use.
Analysis steps
Weigh about 10 g of laboratory sample, accurate to 0.01 g, dissolve it with about 60 mL of carbon dioxide free water and dilute it to 100 mL, which is the sample solution.Take 12mL of sample solution and put it into a 25mL colorimetric tube with a stopper, which is called tube A.Pipette 10mL of lead standard solution and 2mL of sample solution into a 25mL colorimetric tube with a stopper, shake up, and it is called tube B (standard).Suck 10mL of carbon dioxide free water and 2mL of sample solution into a 25mL colorimetric tube with a stopper, shake up, and it is called tube C (blank).In tubes A, B and C, add 2mL of ammonium acetate buffer solution respectively, shake well, drop 1.2mL of ammonium thioacetate solution respectively, stir and mix quickly.Compared with tube C, tube B appears light brown.After 2min, the color of pipe A shall not be deeper than that of pipe B.
Determination of ignition residue
Reagents and materials
Sulfuric acid.
Sulfuric acid solution: 1+8.
Analysis steps
Weigh about 2g~3g of laboratory sample, accurate to 0.0001g, place it in a porcelain crucible that is burned at 800 ℃± 25 ℃ to constant mass, add an appropriate amount of sulfuric acid solution to completely wet the sample.Heat with warm fire until the sample is completely carbonized and cooled.Add about 0.5mL sulfuric acid to wet the residue, and use the above method to heat until the sulfuric acid vapor is exhausted.Burn at 800 ℃± 25 ℃ for 45min.Put it into a dryer to cool to room temperature and weigh it.
Result calculation
The mass fraction of burning residue w2, expressed in%, is calculated according to the formula:
w2=m1/m x 100%
Where:
M - value of sample mass, in gram (g);
M1 - mass value of residue, unit: gram (g).
Take the arithmetic mean of two parallel determination results as the report result.The absolute difference between the two parallel determination results is not more than 0.02%.
Determination of specific rotation
Weigh 10g of laboratory sample, accurate to 0.0001g, add hydrochloric acid solution (1+1) to dissolve it, transfer it to a 100mL volumetric flask, dilute it with hydrochloric acid solution (1+1) to the scale, and shake it up.The value of specific optical rotation α m (20 ℃, D) is expressed in (°) · dm2 · kg-1 and calculated according to the formula:
