Product performance and production technology of 2-hydroxy-1-naphthaldehyde

2-hydroxy-1-naphthaldehyde (2-hydroxy-1-naphthaldehyde ) , also known as 1-formyl-2-naphthol (1-formyl-2-naphthol ), of formula C _.
11 H _.
8 O ₂ , molecular weight 172.
18 , The structural formula is

1.

Product performance

Yellow needle-like crystals ( precipitated in ethyl acetate ), crystallized as prisms in ethanol; boiling point 192°C (3.
59kPa), melting point 82°C; insoluble in water, soluble in ethanol , ether , petroleum ether , alkaline aqueous solution, soluble The concentrated sulfuric acid is a yellow solution; it reacts with iron oxide and is brown; the silica gel layer is expanded (the developing agent is benzene: acetone =2:1, volume ratio), R=0.
89
.

2.
Production principle

There are many production principles of 2-hydroxy-1-naphthaldehyde, among which Duff-Beers method and Reimer-Tiemann method (RT method) are more commonly used
.

In the RT method, β-naphthol and chloroform are reacted in a solvent under alkaline conditions to obtain 2-hydroxy-1-naphthaldehyde

3.

Process flow

4.

Technical formula (kg/t)

5.

Main equipment

Reactor, filter, washing pot, dryer
.

6.
Production process

Add appropriate amount of ethanol and 56kg β-naphthol to the reaction kettle , heat to 40°C, stir for 0.
5h, and then add 30% sodium hydroxide solution
.

Heat and increase the temperature.

After rinsing the crude product with water, add 40 kg of ethanol, heat to dissolve the crude product, and then cool and crystallize
.

After filtering, the filter cake is dried at 50-60°C to obtain yellow crystals, and the product is about 40kg

7.
Laboratory preparation method

Add 200g of β-naphthol, 98g of hexamethylenetetramine and 2000mL of glacial acetic acid into a three-necked reaction flask , heat to reflux for 8h, and then add 2000mL of 1:1 hydrochloric acid, and the reaction solution will become orange-yellow
.

Heat for 5min and let it stand overnight

8.
Product Standard

9.

Product use

Intermediate for organic synthesis and fluorescent whitening agent
.

In the production of fluorescent whitening agent, it is an important intermediate benzocoumarin type fluorescent brighteners, such as fluorescent brighteners OM, TinopalACA, BlankophorACF the like
.
In particular, adding alkyl, aryl, acyl and esterifiable carboxyl groups to the 3-position of 5,6-benzocoumarins such as ACF can form a series of fluorescent whitening agents, except for whitening acrylic fibers.
In addition, it can also whiten acetate, polyamide, polyurethane and other materials, and can also be used in detergents or spinning solutions
.
2-Hydroxy-1-naphthaldehyde is also an analytical reagent for the determination of palladium and beryllium
.

10.
Security measures

(1) The raw materials β-naphthol and chloroform are toxic.
The reaction equipment should be sealed.
The operator should wear labor protection equipment to prevent the reaction material from splashing on the skin.
Keep good ventilation in the workshop
.

(2) The products are packed in iron drums lined with plastic bags and stored in a cool, dry place
.

Related links: Product performance and process flow of m-nitrobenzaldehyde