N, N-Dimethylformamide is called DMF for short. A compound formed by the substitution of hydroxyl groups of formic acid by dimethylamino groups. It is a colorless, transparent, high boiling liquid with light amine flavor and a spontaneous combustion point of 445 ℃. The explosion limit of steam and air mixture is 2.2 ~ 15.2%. In case of an open fire and high heat, it can cause combustion and explosion. It can react violently with concentrated sulfuric acid, fuming nitric acid, and even explode. It is miscible with water and most organic solvents. It is a common solvent for chemical reactions. Pure dimethylformamide has no smell, but industrial-grade or deteriorated dimethylformamide has a fishy smell because it contains impure substances of dimethylamine. The name comes from the fact that it is a dimethyl substituent of formamide (amide of formic acid), and both methyl groups are located on the n (nitrogen) atom.
This substance is a polar (hydrophilic) aprotic solvent with a high boiling point. Chemicalbook can promote the progress of the SN2 reaction mechanism. Dimethylformamide is made from formic acid and dimethylamine. Dimethylformamide is unstable in the presence of strong bases such as sodium hydroxide or strong acids such as hydrochloric acid or sulfuric acid (especially at high temperature) and hydrolyzes to formic acid and dimethylamine. It is very stable in the air and when heated to boiling. When the temperature is higher than 350 ℃, water is lost and carbon monoxide and dimethylamine are generated. N. N-dimethylformamide is a good aprotic polar solvent, which can dissolve most organic and inorganic substances, and is miscible with water, alcohol, ether, aldehyde, ketone, ester, halogenated hydrocarbon, an aromatic hydrocarbon. N. The positively charged end of the N-dimethylformamide molecule is surrounded by methyl, forming a space barrier, so that the negative ions cannot approach, but only associate with the positive ions. The activity of bare negative ions is much greater than that of solvated negative ions. Many ionic reactions are easier to carry out in N, N-dimethylformamide than proton solvents. For example, carboxylates react with halogenated hydrocarbons in N, N-dimethylformamide at room temperature to produce esters with high yield, which is especially suitable for the synthesis of stearic esters
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 to manufacture 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 ℃, 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.
It is a good solvent for the synthesis of polyvinylnitrile and polyacrylonitrile, such as polyvinylamide, which can be used for the synthesis of many kinds of wet fibers, such as polyvinylamide, etc; For plastic film making; It can also be used as paint remover to remove paint; It can also dissolve some pigments with low solubility and make the pigments have the characteristics of dyes. Dimethylformamide is used for aromatic extraction, separation, and recovery of butadiene from the C4 fraction and isoprene from the C5 fraction. It can also be used as an effective reagent for the separation of nonhydrocarbon components from paraffin. It has good selectivity for the solubility of m-phthalic acid and terephthalic acid: the solubility of m-phthalic acid in dimethylformamide is greater than that of terephthalic acid. The two can be separated by solvent extraction or partial crystallization in formamide. In the petrochemical industry, dimethylformamide can be used as a gas absorbent to separate and refine gas. In the polyurethane industry, as a curing agent for washing chemicalbook, it is mainly used in the production of wet synthetic leather; As a solvent in the acrylic fiber industry, it is mainly used in the dry spinning of acrylic fiber; Quenching of tinned parts and cleaning of circuit boards in the electronic industry; Other industries include carriers of dangerous gases, solvents for drug crystallization, adhesives, etc. In organic reactions, dimethylformamide is not only widely used as a reaction solvent, but also an important intermediate in organic synthesis. It can be used to produce Chlordimeform in the pesticide industry; In the pharmaceutical industry, it can be used for the synthesis of iodamine pyrimidine, doxycycline, cortisone, vitamin B6, iodoside, quzhujing, thiadiazine, N-formyl sarcoplasmosin, antitumor acid, methoxyaromatic mustard, Bian nitrogen mustard, cyclohexylnitrourea, furafluorouracil, hemostatic acid, betamethasone, medroxyprogesterone, cholevita, chlorpheniramine, and sulfonamides. Dimethyl Dimethy lformamidelformamide plays a catalytic role in the reactions of hydrogenation, dehydrogenation, dehydration, and dehydrohalogenation, which reduces the reaction temperature and improves the purity of the product.