2,3-DIHYDROXYBENZOIC ACID

PRODUCT IDENTIFICATION
CAS NO. 303-38-8

2,3-DIHYDROXYBENZOIC ACID

EINECS NO. 206-139-5
FORMULA (HO)2C6H3COOH
MOL WT. 154.12

H.S. CODE

  

TOXICITY

  
SYNONYMS 3-Hydroxysalicylic acid; Catecholcarboxylic acid;
2,3-DHB; 2-Pyrocatechuic acid; 2,3-Dioxybenzoic Acid;
DERIVATION

 

CLASSIFICATION

  

PHYSICAL AND CHEMICAL PROPERTIES

PHYSICAL STATE white crystalline powder
MELTING POINT 204- 206 C (Sublimes)
BOILING POINT

 

SPECIFIC GRAVITY

 

SOLUBILITY IN WATER Soluble
pH  
VAPOR DENSITY

 

REFRACTIVE INDEX

 

NFPA RATINGS

 Health: 2 ; Flammability: 0 ; Reactivity: 0

AUTOIGNITION

 

FLASH POINT

 

STABILITY Stable under normal conditions.

APPLICATIONS
Benzoic acid, the simplest aromatic carboxylic acid containing carboxyl group bonded directly to benzene ring, is a white, crystalline organic compound; melting at 122 C (starting sublime at 100 C);  boiling at 249 C; slightly soluble in water, soluble in ethanol, very slightly soluble in benzene and acetone. Its aqua solution is weakly acidic. It occurs naturally in many plants  and resins. Benzoic acid is also detected in animals. The most of commercial benzoic acid is produced by the reaction of toluene with oxygen at temperatures around 200 C in the liquid phase and in the presence of cobalt and manganese salts as catalysts. It can be prepared also by the oxidation of benzene with concentrated sulphuric acid or carbon dioxide in the presence of catalysts. Other methods are such as by the oxidation of benzyl alcohol, benzaldehyde, cinnamic acid; by hydrolysis of benzonitrile, benzoyl chloride. More than 90% of commercial benzoic acid is converted directly to phenol and caprolactam. Its use in the production of glycol benzoates for the application of plasticizer in adhesive formulations is increasing. It is also used in the manufacture of alkyd resins and drilling mud additive for crude oil recovery applications. It is used as a rubber polymerization activators and retardants. Benzoic acid is converted to its salts and esters for the use of preservative application in foods, drugs and personal products. Sodium benzoate, sodium salt of benzoic acid, is used preferably as one of the principal anti-microbial preservatives used in foods and beverages (but it's concentration is limited usually not exceeding 0.1% because it is poisonous), as it is about 200 times more soluble than benzoic acid. Sodium Benzoate is also used in medications, anti-fermentation additives and tabletting lubricant for pharmaceuticals. The industrial applications are as a corrosion inhibitor, as an additive to automotive engine antifreeze coolants and in other waterborne systems, as a nucleating agents for polyolefin, as a dye intermediate, as a stabilizer in photographic processing and as a catalyst. Wide range of benzoic esters are used as solvents, dying carrier, disinfectant additive, penetrating agent and pesticides and manufacturing other compounds.

There are six isomeric compounds of dihydroxybenzoic acids which have two -OH groups and one carboxylic group on the benzene ring.

2,3-Dihydroxybenzoic acid
(2-Pyrocatechuic acid)

2,4-Dihydroxybenzoic acid
(beta-Resorcylic acid)

2,5-Dihydroxybenzoic acid
(Gentisic acid)

2,3-Dihydroxybenzoic acid

2,4-Dihydroxybenzoic acid

2,5-Dihydroxybenzoic acid

CAS RN: 303-38-8
Melting Point: 204 - 206 C

CAS RN: 89-86-1
Melting Point:208 - 211 C

CAS RN: 490-79-9
Melting Point:200 - 205 C

 

 

 

2,6-Dihydroxybenzoic acid
(gamma-Resorcylic acid)

3,4-Dihydroxybenzoic acid
(Protocatechuic acid)

3,5-Dihydroxybenzoic acid
(alpha-Resorcylic acid)

2,6-Dihydroxybenzoic acid

3,4-Dihydroxybenzoic acid

3,5-Dihydroxybenzoic acid

CAS RN: 303-07-1
Melting Point: 165 C

CAS RN: 99-50-3
Melting Point: 200 - 202 C

CAS RN: 99-10-5
Melting Point: 235 - 237 C

Gentisic acid, having a carboxylic group and two -OH at quinol position, is a crystalline powder that forms monoclinic prism in water solution. It is soluble in water, alcohol, ether, polar organic solvents and salts; sublimes at 200C and lemts at 205 C. 5-Hydroxysalicylic acid is another structural name of gentisic acid. Benzoic acid derivatives substituted by hydroxy group or ether containing oxygen atom have active bacteriostatic and  fragrant properties. They are typically used in pharmaceutical and perfumery industry. The destructive metabolic property of oxygen containing benzoic acid derivatives such as protocatechuic acid (3,4-dihydroxybenzoic acid) and veratric acid (3,4-dimethoxybenzoic acid) is used in the application for pharmaceuticals. Protocatechuic acid is a catabolite of epinephrine. Protocatechuic acid itself is used as an anticarcinogenic agent. Prazosin, a peripheral vasodilator and antihypertensive, is also an example of the applicaion of veratric acid. Hydroxyl group substituted benzoic acids feature analogue metabolite of aspirin (acetylsalicylic Acid). Diacetate ester of 2,3-dihydroxybenzoic acid, dipyrocetyl, is an analogue of aspirin used as an analgesic and antipyretic. Dihydroxybenzoic acids are used as intermediates for pharmaceuticals (especially for antipyetic anlgesic, antirheumatism) and other organic synthesis. They are used as matrix for ionization of peptides, proteins and carbohydrates. In industrial field, they are used as intermediates for the production of other organic chemicals, resins, polyesters, plasticizers, dyestuffs, preservatives, and rubber chemicals.

SALES SPECIFICATION

APPEARANCE

 white crystalline powder

ASSAY

99.0% m in

MELTING POINT

 202 - 206 C
LOSS ON DRYING

0.5% max
RESIDUE ON IGNITION

0.1% max
TRANSPORTATION
PACKING
25kgs in  Bag
HAZARD CLASS  
UN NO.  
OTHER INFORMATION
Hazard Symbols: XI, Risk Phrases: 36/37/38, Safety Phrases: 26-36