Do you know the health hazards of glyoxal?

Invasion pathways: inhalation, ingestion and percutaneous absorption.

Health hazards: Inhalation, intake or skin absorption may be harmful to human body. Steam or smoke can irritate eyes, skin, mucosa and upper respiratory tract.

Toxicity: Medium toxicity. It has slight irritation to eyes and nasal mucosa and can cause hyperemesis in animals. Chronic poisoning can cause pancreatic damage.

Acute toxicity: LD50 2020 mg/kg (rat oral); 200 mg/kg (mouse abdominal cavity)

Hazard characteristics: strong reducibility. Contact with air can cause explosion. Strong polymerization occurs in the presence of water. It reacts strongly with chlorosulfonic acid, ethyleneimine, nitric acid, fuming sulfuric acid and sodium hydroxide. Toxic and irritating smoke is emitted when burning.

Combustion (decomposition) products: carbon monoxide, carbon dichloride.

Preparation

In industry, glyoxal can be prepared by gas phase oxidation of ethylene glycol catalyzed by silver or copper or by oxidation of acetaldehyde with nitric acid solution. In the laboratory, glyoxal is prepared by oxidizing acetaldehyde with selenite. Anhydrous glyoxal can be prepared by co-heating solid hydrate with phosphorus pentoxide.

application

The applications of glyoxal include:

Used as solvents and crosslinkers in polymer chemistry for organic synthesis, especially for the construction of heterocycles such as imidazole

solution

Usually glyoxal is sold in 40% solution. Like other small aldehydes, it can form hydrates and condensate to form a series of "oligomers", whose structure is not yet clear. At least two types of hydrates are currently on sale:

Dimeric glyoxal dihydrate: [(CHO)2]2[H_2O]2, trans-2,3-dihydroxy-1,4-dioxane (CAS4845-50-5, m.p.91-95 C) triglyoxal dihydrate: [(CHO)2]3 (H_2O)4 (CAS 4405-13-4). It is estimated that when the concentration of glyoxal solution is below 1M, it mainly exists in the form of monomer or hydrate, namely OCHCHO, OCH (OH) or (CH2H) O2. When the concentration is more than 1M, it is mainly dimer type, possibly acetal/ketone structure, and the molecular formula is [(HO) CH] 2O2CHO.