Production principle and process flow of 1-hydroxy-2-naphthoic acid

1-hydroxy-2-naphthoic acid (1-hydroxy-2-naphthoic acid, 1-hydroxy-2-naphthalenecarboxylicacid), also known as 1-naphthol 2-carboxylic acid (1-naphthol-2-carboxylic acid), 1 , 2-acid, molecular formula is C ₁₁ H ₈ O ₃ , molecular weight is 188.
18, structural formula is

1.
Product performance

White needle-like crystals; industrial products are in powder form; melting point is 191～192℃; easily soluble in ethanol , ether , benzene, chloroform and alkaline solutions, insoluble in cold water, slightly soluble in hot water; its sulfuric acid solution is irradiated by ultraviolet light The bottom is blue-blue fluorescence
.

2.
Production principle

In the chlorobenzene solvent, a-naphthol reacts with carbon dioxide to form sodium carbonate after being salted, and acidified to obtain 1-hydroxy-2-naphthoic acid after rearrangement
.

3.
Process flow

4.
Technical formula (kg/t)

5.
Main equipment

Reaction kettle, rearrangement reaction pot, filter, storage tank, dryer
.

6.
Production process

In the reactor, the solvent chlorobenzene is first added, then a-naphthol is added, and 30% sodium hydroxide is added with stirring to obtain sodium a-naphthol
.
Carbon dioxide is introduced for carboxylation reaction to generate sodium carbonate-a-naphtholate

7.
Product Standard

8.
Quality inspection

1) Assay

Weigh 0.
8g of 1-hydroxy-2-naphthoic acid sample (weigh to 0.
0002g), put it in a 250mL Erlenmeyer flask, add 30mL ethanol to dissolve, add 0.
5mL 1-naphthophthalein indicator, use 0.
1mol/L The sodium hydroxide standard solution is titrated until the solution changes to light yellow-green as the end point
.
Do a blank experiment under the same conditions

In the formula: V——The volume of sodium hydroxide standard solution used to titrate the sample, mL;

V ₁ ——The volume of sodium hydroxide standard solution used in the blank experiment, mL;

c——The molar concentration of sodium hydroxide standard solution, mol/L;

G——The mass of the sample, g
.

2) Melting point determination

According to GB/T617-2006 "General Method for the Determination of the Melting Point of Chemical Reagents"
.

9.
Product use

Dye intermediates
.
Mordant dyes used for producing blue, green and acid mordant dyes and the like

10.
Security measures

(1) The raw material a-naphthol is toxic, easy to sublime, can be absorbed through the skin and poisoned, and is irritating to the eyes and mucous membranes
.
The reaction equipment should be sealed, and the operator should wear labor protection equipment

(2) The product is poisonous and is packed in plastic bags lined with plywood drums or iron drums for external use
.
Store in a dry and ventilated warehouse to prevent heat, moisture and sunlight

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