Chemical use of pharmaceutical grade benzoic acid

Pharmaceutical grade benzoic acid chemical propertiesUse benzoic acid is shiny, white, monoclinic flakes or needle-like knots
.
Light, odorless or slightly similar to
benzoin.
Its vapor is very irritating and easy to cause cough
after inhalation.
Can volatilize
with water vapor.
Sublimation begins at about 100 °C [9].

1 g benzoic acid is soluble in 2.
3 mL cold ethanol, 1.
5 mL boiling ethanol, 4.
5 mL chloroform, 3 mL B, 3 mL acetone, 30 mL carbon tetrachloride, 10 mL benzene, 30 mL carbon disulfide, 23 mL turpentine
.
The solubility in water increases with the presence of alkaline substances (such as borax, trisodium phosphate) and benzoic acid, also known as benzoic acid, molecular formula is C6H5COOH, a simple aromatic acid whose carboxyl group is directly connected to the carbon atom of the benzene ring, which is a compound
formed by the substitution of a hydrogen group (-COOH) on the benzene ring.
It is colorless, odorless flaky crystals
.
Melting point 122.
13 °c, boiling point 249 °c, relative density 1.
2659 (15/4 °C).

Rapidly sublimated at 100 °C, its vapor has a strong irritation, easy to cause cough
after inhalation.
Slightly soluble in water, soluble in ethanol, ethyl, chloroform, benzene, Chemicalbook toluene, carbon disulfide, carbon tetrachloride and turpentine and other organic solvents
.
is widely present in nature in the form of free acids, esters or derivatives thereof, for example, in the form of free acids and benzyl esters in benzoin gum; exists in free form in the leaves and stem bark of some plants; in the form of methyl or benzyl esters in essential oils; In horse urine in the form of its derivative hippuric acid
.
Benzoic acid is a weak acid, stronger
than fatty acids.
Their chemical properties are similar, can form salts, esters, acid halides, amide, anhydride, etc.
, are not easy to be oxidized ethanol solution clarity and color take 5.
0g of this product, add ethanol to dissolve and dilute to 100ml, the solution should be clear and colorless
.
Take 6.
7g of this product and put 6.
7g of this product in a 100ml measuring flask, add 40ml of lmol/L sodium hydroxide solution and 50ml of ethanol to dissolve, dilute to the scale with water, and shake well
.
take 10ml of the above solution, add 7.
5ml of 2mol/L sodium hydroxide solution and 0.
125g of nickel-aluminum alloy, heat on a water bath for 10 minutes, cool, filter, put the filtrate in a 25ml measuring flask, wash the filtrate with ethanol 3 times, 2ml each time, wash the solution and human filtrate, dilute it with water to the scale, as solution A
.
The blank solution was prepared as solution B
by the same method.
(The glass instrument used in this experiment must be soaked in 500g/L nitric acid solution overnight before use, washed with water and filled with water to ensure that there is no chlorine
.
) Take solution A, solution B, standard chloride solution [take 0.
132% (W / V) sodium chloride solution lm l in a 100ml measuring flask, dilute to the scale with water, and use a new one] and 10ml of water, put them in 25ml measuring flasks respectively, add ammonium ferric sulfate solution (take 30g of ammonium ferric sulfate, add 40ml of nitric acid, shake, dilute to 100ml with water, filter, and obtain
.
The solution should be stored in the dark) 5ml, shake well, add 2ml of nitric acid dropwise (shake while adding), add absolute ethanol to dissolve into 100ml, that is
.
After preparation, use 5ml within 7 days), shake, dilute with water to the scale, and leave in a water bath at 20 °C for 15 minutes
.
According to UV-Vis spectrophotometry (General 0401), the absorbance of solution A (with solution B as blank) and standard chloride solution (with water as blank) is measured at a wavelength of 460nm, respectively, and the absorbance of solution A shall not be greater than the absorbance of standard chloride solution (0.
03%)
。 Easy oxide take 100ml of water, add 1.
5ml of sulfuric acid, after boiling, add potassium manganate titration solution (0.
02mol/L) dropwise, until the pink color does not disappear for 30 seconds, add 1.
0g of this product while hot, after dissolution, add potassium permanganate titration solution (0.
02mol/L) 0.
25ml, should be pink color, and do not disappear
within 15 seconds 。 Easy carbide take 0.
5g of this product, add sulfuric acid [containing H2S04 94.
5% to 95.
5% (g/g)] 5ml shaking, place for 5 minutes, compared with yellow No.
2 standard colorimetric solution, not deeper
.
The ignition residue shall not exceed 0.
1 % (General Rule 0841).

Heavy metals take this product l.
Og, add 22ml of ethanol to dissolve, add 2ml of acetate buffer (pH 3.
5) and an appropriate amount of water to make 25ml, check according to law (General 0821 first method), containing heavy metals shall not exceed 10
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