N, N-dimethylformamide (DMF) is widely used as a pharmaceutical solvent. N. N-dimethylformamide is a dipolar hydrophilic solvent with physicochemical properties, so it is suitable for capillary electrophoresis (CE)
The chemical properties of N-dimethylformamide are very stable, which are shown in the following seven aspects:
1. It is an aprotic polar solvent with good solubility to a variety of organic and inorganic compounds. It has good chemical stability in the absence of alkali, acid, and water.
2. Chemical properties: in the absence of acid, alkali, and water, it is relatively stable even when heated to the boiling point. It is decomposed into formic acid and dimethylamine salt under the action of acid, while it is decomposed into methylate and dimethylamine under the action of alkali.
3. Decompose into dimethylamine and formaldehyde under the action of ultraviolet light, and decompose into dimethylamine and carbon monoxide when heated to about 350 degree . It forms a relatively stable equimolar adduct with hydrochloric acid, with a melting point of 40 degree and a boiling point of 110 degree . It can also form crystalline adducts with SO3, with a melting point of 138 degree and a boiling point of 145 degree . Dmf-so3 can be used as a mild sulfonating agent and sulfating agent. The adducts formed with POCl3, CoCl2, and SOCl2 can introduce the Cho group (Vilsmeier reaction) into the aromatic ring with high electron density. P2O5 is insoluble in Dimethylformamide at room temperature, but after forming a stable complex above 40 degree , it can be dissolved at room temperature without precipitation. When heated in the presence of metallic sodium, a violent reaction occurs and hydrogen is released. It can also react violently with triethylaluminum at 0 degree . It can also react with the Grignard reagent. When reacting with acyl chloride and anhydride, it produces derivatives of dicarbonamide.
4. It belongs to the low toxicity category. Animal experiments have proved that continuous administration of a large amount of N, N-dimethylformamide can cause weight loss and hinder hematopoietic function. It has a strong stimulating effect on the eyes, skin, and mucous membrane, and its liquid or vapor can also cause liver disorders after being absorbed by the skin. Inhalation of high concentration steam can cause acute poisoning. The main symptoms are severe irritation, general spasm, painful constipation, nausea, and vomiting. In addition to skin and mucous membrane irritation, chronic poisoning also includes nausea, vomiting, chest tightness, headache, general discomfort, loss of appetite, stomach pain, constipation, hepatomegaly, changes in liver function, and the increase of urobilinogen and urobilin. When in use, the average vapor concentration is required to be below 29.9mg/m3, and poisoning symptoms (damaging the central nervous system) will appear when it is 59.8mg/m3. The oral toxicity LD50 of rats and mice was 3000 7000 mg/kg. The olfactory threshold concentration is 0.14mg/m3, and TJ 36-79 stipulates that the maximum allowable concentration in the air of the workshop is 10mg / m3.
5. Stability
6. Prohibited substances: strong oxidant, acyl chloride, chloroform, strong reducing agent, halogen, chlorinated hydrocarbon, concentrated sulfuric acid, fuming nitric acid
7. Polymerization hazard non-polymerization
Dimethylformamide is mainly used as a low volatile solvent. Dimethylformamide is used in the manufacture of propylene fibers and plastics. In the pharmaceutical industry, it is also used in the manufacture of pesticides, adhesives, artificial leather, fibers, films, and surface coatings. Dimethylformamide is the reagent of bouveault aldehyde synthesis reaction and Vilsmeier Haack reaction (another useful aldehyde synthesis reaction). In the NMR spectrum, the proton on the methyl group of dimethylformamide forms two single peaks, because the rotation rate of the carbonyl carbon-nitrogen bond is very slow in the time scale of NMR. The bond order of carbonyl carbon-nitrogen bond is greater than one, while that of amide carbon-oxygen bond is less than two. In the infrared spectrum of amide, the chemicalbook, C = O band is usually less than 1700cm-1, because its C = O bond is weakened due to the electron density of oxygen supplied from nitrogen. Dimethylformamide will penetrate most plastics and expand them, so it is often used as one of the components of paint remover. Dimethylformamide is also known as a "universal solvent", but it also has its limitations. It has a high boiling point of 154 degree , which is more suitable as a solvent for many polymer materials. It should be carefully selected in organic synthesis. It is often difficult to remove the solvent. In addition, it can be miscible with water. The simple solvent recovery method is difficult to dehydrate. It can be washed off with water at any cost. The feasibility of large-scale production should be considered in the small-scale test. We need to calculate the cost and wastewater treatment scheme.
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