1. What is DMF?
DMF, short for dimethylamide, is an organic compound with the formula HCON(CH?). ? It is a colorless transparent liquid and can be miscible with water and most organic solvents. Pure dimethylformamide has a special odor, and industrial grade or deteriorated dimethylformamide has a fishy smell because it contains an impure dimethylamine. The name derives from the fact that it is a dimethyl substitute for formamide (the amide of formic acid), and both methyl groups are located on the N (nitrogen) atom. It is a common solvent for chemical reactions. As a polar (hydrophilic) aprotic solvent with a high boiling point, it can promote SN? The process of reaction mechanism. Dimethylformamide is made from methyl formate and dimethylamine. Dimethylformamide is unstable in the presence of strong bases such as sodium hydroxide or strong acids such as hydrochloric or sulfuric acid (especially at high temperatures) and hydrolyzes to formic acid and dimethylamine with the equation HCON(CH?). ? +H? O → (CH?) ? NH+HCOOH.
On October 27, 2017, the preliminary list of carcinogens published by the World Health Organization's International Agency for Research on Cancer was collated for reference, and dimethylformamide was in the list of Class 2A carcinogens.
2. Chemical properties of DMF
Spontaneous ignition point 445℃. The explosive limit of the mixture of steam and air is 2.2-15.2%. In case of open fire, high heat can cause combustion explosion. It can react violently with concentrated sulfuric acid and fuming nitric acid and even explode.
Third, the main uses of DMF
Use one; It is used as an analytical reagent and as a solvent for ethylene resin and acetylene [5].
Use 2; Is an excellent organic solvent, used as polyurethane, polyacrylonitrile, polyvinyl chloride solvent, also used as extraction agent, medicine and pesticide chloramidine raw material.
Use three; Dimethylformamide is not only a very widely used chemical raw material, but also a very widely used excellent solvent. It can be used for wet spinning of synthetic fibers such as polyacrylonitrile fibers and synthesis of polyurethane. Used for plastic film making; Can also be used to remove paint stripper; It can also dissolve some low solubility pigments, so that the pigment has the characteristics of dyes. Dimethylformamide can be used for aromatics extraction and for the separation and recovery of butadiene from C-4 fractions and isoprene from C-5 fractions. It can also be used as an effective reagent for the separation of non-hydrocarbon components from paraffin.
It has good selectivity for the solubility of isophthalic acid and terephthalic acid: the solubility of isophthalic acid in dimethylformamide is greater than that of terephthalic acid, and the two can be separated by solvent extraction or partial crystallization in dimethylformamide. In the petrochemical industry, dimethylformamide is used as a gas absorber to separate and refine gases. In organic reactions, dimethylformamide is not only widely used as a solvent, but also an important intermediate in organic synthesis. It can be used to produce chloramidine in the pesticide industry; In the pharmaceutical industry, it can be used for the synthesis of sulfadiazine, doxycycline, cortisone, vitamin B6, iodoside, pamotin, thiacil, N-formylsarcomylate, antitumine, methoxyluridine, benazine, cyclohexanitrourea, fururacil, styptic acid, befenamethasone, megestrol, bilviuta, pramine and so on. Dimethylformamide plays a catalytic role in hydrogenation, dehydrogenation, dehydration and dehalogenation reactions, which reduces reaction temperature and improves
product purity.
Use four; Non-aqueous titration reagents, solvents of ethylene resin and acetylene, organic synthesis, photometry, gas chromatography fixed solution (maximum operating temperature 50℃, solvent is methanol), separation and analysis of C2-C5 hydrocarbons, and can separate N-isobutene -[1] and cis-butene -[2]. Pesticide residue analysis. Organic synthesis. Synthesis of peptides. For the photographic
industry.
Iv. Health hazards of DMF
Invasion route: inhalation, ingestion, percutaneous absorption.
Health hazards:
Acute poisoning: main symptoms of eye and upper respiratory tract irritation, headache, anxiety, nausea, vomiting, abdominal pain, constipation, etc. Liver damage generally appears a few days after poisoning, liver enlargement, liver pain, may appear jaundice. Through the skin absorption of poison, the skin appears blisters, edema, sticky rough, local numbness, itching, burning pain.
Chronic effects: skin and mucosa irritation, neurasthenic syndrome, low blood pressure. There are nausea, vomiting, chest tightness, loss of appetite, stomach pain, constipation and liver function changes.
5. Can DMF be recycled?
Because DMF has certain toxicity, direct discharge of waste liquid will cause serious harm to the environment, and its chemical characteristics determine that DMF can be recycled through a certain way. In line with saving emission reduction, sustainable development of the road.
