What is sodium acetate?

Molecular formula: C2H3NaO2? NH2O(n=3 or 0) [3]

Relative molecular weight: 136.08 (trihydrate) [3]

82.03 (anhydrous) [3]

Colorless and transparent monoclinic prism crystal or white crystalline powder, odorless or slightly vinegar-flavored, slightly bitter, easily weathered in dry and humid air. The relative density is 1.45. Heat it to 58℃ and dissolve it in crystal water. At 120℃, crystal water is lost and becomes white powder. When it is higher than 3 15℃, it melts and decomposes into sodium carbonate. Soluble in water (46.5g/ 100mL, 20℃, 0. 1mol/L, pH 8.87), acetone, etc. , soluble in ethanol, insoluble in ether. [3]

Relative density: 1.45 (trihydrate); 1.528 (anhydrous) [2]

Refractive index: 1.464[2]

Melting point (℃): 58 [2]

Solubility: Soluble in water, ethanol and ether. [2]

Computational chemical data

1. Reference value for calculation of hydrophobic parameters (XlogP): None [2]

2. Number of hydrogen bond donors: 0[2]

3. Number of hydrogen bond acceptors: 2[2]

4. Number of rotatable chemical bonds: 0[2]

5. Number of tautomers: None [2]

6. Polar surface area of topological molecules: 40. 1[2]

7. Number of heavy atoms: 5[2]

8. Surface charge: 0[2]

9. Complexity: 34.6[2]

10, number of isotope atoms: 0[2]

1 1. Determine the number of atomic solid centers: 0[2]

12, the number of uncertain atomic solid centers: 0[2]

13. Determine the number of solid centers of chemical bonds: 0[2]

14, the number of uncertain chemical bond solid centers: 0[2]

15, number of covalent bond units: 2[2]

Toxicological data

1, skin/eye irritation:

Rabbit skin standard Dretz eye staining test: 500mg/24H has slight irritation to skin. [2]

Standard Dreitz eye staining test of rabbit eyes: 50ug/24H has slight irritation to eyes. [2]

2. Acute toxicity:

Rats were given oral ld50:3530mg/kg[2].

Rats inhaled LC50: > 30gm/m3/ 1H[2]

Mice were given oral LD50:689 1mg/kg[2].

Subcutaneous LD50 of mice: 3200mg/kg [2]

Mice were injected with LDLO:1195 mg/kg [2] intravenously.

Ld50 of rabbit skin: >10 mg/kg [2]

Ldlo:1300mg/kg was injected intravenously into rabbits [2].

synthetic method

1. Put sodium acetate trihydrate in a porcelain dish and heat it at 65438 020℃ to obtain dry white material and anhydrous sodium acetate. [2]

For example, in organic synthesis, when anhydrous sodium acetate and alkali lime are used to prepare methane, anhydrous sodium acetate should be prepared before use. A proper amount of sodium acetate trihydrate is put into a porcelain evaporating dish, and when it is heated to about 58℃ under the stirring of a glass rod, the sodium acetate trihydrate is dissolved in crystal water, and the water gradually evaporates to obtain a white solid, at which time the temperature is about 65438 020℃. Continue heating until the solid melts, but the temperature should not exceed the melting point of sodium acetate trihydrate (324℃) to avoid the decomposition of sodium acetate into acetone and sodium carbonate. Cool slightly under stirring, grind in a mortar while it is hot, and immediately store it in a closed container for later use. [2]

ca(ch 3c oo)2+naco 3→2ch2 coona+CaCO3[2]

2. Neutralize acetic acid with crystalline sodium carbonate, filter, evaporate, cool, crystallize and dry at room temperature. [2]

3. Calcium acetate is treated with sodium sulfate and sodium bicarbonate. [2]

4. There are many ways to produce sodium acetate, which can be obtained by reacting dilute acetic acid or calcium acetate with soda ash; It can also be obtained by double decomposition of sodium sulfate and calcium acetate. In industry, sodium acetate is often recovered from the leftovers of pharmaceutical factories and perfume factories. [2]

628 kg of dilute acetic acid was poured into the reactor, and 200 kg of soda ash was added into the reactor several times. Don't stir, start the induced draft fan to draw air. After the reaction is stable, start stirring to fully react soda ash and acetic acid, then pump it into an evaporator to heat and concentrate until the liquid density is 1.24g/cm3, and stop heating. The reaction solution was filtered and pumped into a crystallizer, the Ph value was adjusted to 9.2 with NaOH, and then cooled to 35℃ for crystallization. The surface mother liquor was pumped out, and 350 kg of white powder product was obtained by rotary drying and crystallization. The primary yield is about 70%. [2]

use

1, determination of lead, zinc, aluminum, iron, cobalt, antimony, nickel and tin. Complexing stabilizer. Acetylation AIDS, buffers, desiccants and mordants. [2]

2. Used for the determination of lead, zinc, aluminum, iron, cobalt, antimony, nickel and tin. Used as esterifying agent for organic synthesis, photographic medicine, medicine, dyeing mordant, buffer, chemical reagent, meat preservative, pigment, tanning and many other aspects. [2]

3. Used as buffer, flavoring agent, flavoring agent and ph regulator. 0. 1%-0.3% can be used as a buffer of flavoring agent to relieve bad smell, prevent discoloration and improve flavor. It has certain mildew-proof effect, such as using 0. 1%-0.3% in surimi products and bread. It can also be used as sour agent for soy sauce, pickles, mayonnaise, fish cake, sausage, bread, sticky cake and so on. Mix with methyl cellulose, phosphate, etc. Used to improve the preservation of sausages, bread, sticky cakes, etc. [2]

4. Used as an anti-coking agent for sulfur-adjusted chloroprene rubber, the dosage is generally 0.5 parts by mass. It can also be used as a crosslinking agent for animal glue. [2]

5. This product can be used for alkaline tin electroplating, but it has no obvious influence on the coating and electroplating process and is not an essential component. Sodium acetate is often used as a buffer, such as acidic zinc plating, alkaline tin plating and electroless nickel plating. [2]

Identification method

Sodium salt reaction of 1.5% sample solution: mix sodium chloride or sodium nitrate solution with 5 times of cobalt acetate test solution (take 40g of cobalt acetate crystal, add it into the mixed solution of 30g glacial acetic acid and water, adjust the volume to 500mL, and heat to dissolve) to generate golden yellow precipitate. [3]

2. Acetate reaction: neutral acetate solution meets ferric chloride test solution (taking ferric chloride FeCl3? 6H2O 9g, dissolved in water to a constant volume of 100mL, about 1mol/L) can produce deep red, but if inorganic salts are added, the color will be destroyed. [3]

3, infrared spectrum test, should conform to the standards of infrared spectrum. [3]

Content determination

principle

Sodium acetate is a very weak alkali (pKb=9.24) in aqueous solution, so it can't be titrated accurately with strong acid in water, and it needs non-aqueous titration. Choosing a suitable solvent such as glacial acetic acid can greatly improve the alkalinity of sodium acetate, and HClO4 can be used as the standard solution for titration. The titration reaction is as follows: [4]

H2Ac++？ ClO4-+ NaAc = 2HAc + NaClO4[4]

Potassium hydrogen phthalate is often used to calibrate HClO4? The reaction of reference substance of HAc standard solution is as follows: [4]

C6H4？ Hey? Cook+H2Ac++? ClO4-= C6H4？ Hey? COOH + HAc + KClO4[4]

Because the products determined and calibrated are NaClO4 and KClO4, which have little solubility in non-aqueous media, the titration process is accompanied by HClO4? With the continuous addition of HAc standard solution, white turbidity is gradually produced, but it does not affect the titration results. In this experiment, the mixed solvent of acetic anhydride and glacial acetic acid was selected, and crystal violet was used as indicator to titrate with standard perchloric acid-glacial acetic acid solution. [4]

step

1、HClO4？ Calibration of HAc titrant

Accurately weigh KHC8H4O40. 15-0.2g into a dry conical flask, add 20-25mL glacial acetic acid to dissolve it, add 1 drop crystal violet indicator, and use HClO4? HAc(0. 1mol/L) was titrated slowly until the solution was stable blue (purplish), and three copies were determined in parallel. Take the same amount of glacial acetic acid for blank test correction. According to the quality of KHC8H4O4 and the consumed HClO4? The volume of HAc, calculate the concentration of HClO4 solution. [4]

2. Determination of sodium acetate content

Accurately weigh 0. 1g anhydrous sodium acetate (0.25g sample sodium acetate trihydrate), put it in a clean and dry 250mL conical flask, add 20mL glacial acetic acid to completely dissolve it, add 5mL acetic anhydride, add 1 drop crystal violet indicator, and use 0. 1mol/LHClO4? The HAc standard solution drops until the solution changes from purple to blue, which is the end point. Three copies were determined in parallel, and the results were corrected by blank test. According to the consumption of HClO4? HAc volume (mL), calculate the mass fraction of sodium acetate in the sample. [4]

Matters needing attention

Acetic anhydride (CH3CO)2O is formed by removing 1 H2O from two acetic acid molecules. Because 72%HClO4 solution contains water, acetic anhydride reacts violently with water, and the reaction formula is [4].

(CH3CO)2O + H2O = 2CH3COOH[4]

At the same time, it releases a lot of heat, and overheating is easy to cause HClO4 explosion. Therefore, perchloric acid and acetic anhydride can't be directly mixed during preparation, so HClO4 can only be slowly dropped into glacial acetic acid, and then acetic anhydride can be added dropwise. [4]

Storage method

1, sealed and dried. [2]

2. Packing with inner plastic bag, outer woven bag or gunny bag. Sodium acetate is deliquescent, so attention should be paid to moistureproof during storage and transportation, and contact with corrosive gases is strictly prohibited to prevent exposure and rain, and a rain cover should be added during transportation.