Tuesday, September 17, 2013


Methylal is a new type of solvent. Methylal has the characteristics of solubility, no toxicity and no air pollution. Methylal can replace traditional solvent of acetone, benzene, toluene, Freon, etc. and can be used in the industries of fungicides, industrial detergents, leather polishing agent, cosmetics, pharmaceuticals, etc. Methylal greatly reduces the discharge of toxic organic compounds and reduces atmospheric pollution. Methylal is a green and environmentally friendly product and has a broad development prospect.
Methylal, also called dimethoxymethane (DMM), has the molecular formula CH3O-CH2-OCH3.  It is a liquid at ambient temperature and pressure, with a boiling point of 42.3°C, flash point of -17.8°C and a melting point of -104.8°C.
Methylal hazards and first aid measures
Methylal is irritating to mucous membrane and has anesthetic effects. Inhalation of vapors may cause nose and throat irritation. Inhalation of high-concentration methylal can cause dizziness and other symptoms. Methylal is harmful to the eyes and the hurt can last for several days. Long-term methylal contact can cause dry skin.
Methylal is a condensation product of methanol and formaldehyde and has low toxicity and corrosiveness, which makes it an ideal substitute solvent for benzene, toluene, xylene, acetone, etc. which are for example commonly used in painting industries.
First aid measures
Skin Contact: Remove contaminated clothing, and wash the skin thoroughly with soap and water.
Eye contact: Lift the eyelids; Wash the eyes with moving water or saline water, and go to see a doctor.
Methylal inhalation: Rapidly move from the scene to places with fresh air; maintain the respiratory tract clear; if breathing is difficult, oxygen should be provided; if breathing stops, artificial respiration should be immediately carried out, and a doctor should be sent.
Methylal ingestion: Drink enough warm water; apply the emetic method and go to see a doctor.
Methylal clean production technology
Methylal has excellent physical and chemical properties, good degreasing capability and volatile property. Methylal can be used as detergent for replacing F11, F113, and chlorinated solvents. Therefore, methylal is a environmental protective product for replacing Freon to reduce volatile organic compounds (VOCs) emissions and reduce air pollution. Due to its dissolution characteristic, methylal can be used as a substitute for part of the halogen hydrocarbon solvent. Methylal has good miscibility with many solvents, especially LPG, of DME. Methylal has low boiling point which is helpful to improve the steam pressure and atomization rate of aerosol. Methylal has excellent solubility in water and provides good prospects for the development of water-based aerosol.
As methylal is regarded as being an environmentally friendly solvent, it can replace many of the oil downstream products of which are relatively toxic solvents and chemicals.  In the past two years, China in particular has led the way and implemented methylal use in many areas.
Production technology of high-concentration methylal
Methylal synthesis uses sulfuric acid as catalyst at all times, but the sulfuric acid has severe corrosion to the equipment. With the development of methylal technology, solid resin is used as catalyst, the combination technique of reaction and distillation is developed, and then yield and quality are greatly improved. With the help of methylal plant, general-concentration methylal is processed into low-concentration methylal, 92% methylal is pressed into the differential pressure distillation column for pressure distillation. Pressure is controlled at 1.2-1.5Mpa, the top temperature of the distillation column is controlled at 120 ℃, and the bottom temperature of the distillation column is controlled at 135 ℃. High concentration methylal is produced at the bottom, distillate at the top of column flow back to the reaction column and thepressure distillation column.
The combination of methylal physical properties such as low molecular weight, minimal viscosity and high solvent power make methylal an ideal candidate for application in environmentally friendly paint strippers.
How far does methanol-formaldehyde-methylal chain can go?
The methylal technology is produced by the condensation reaction of methanol and formaldehyde. The operation of a huge amount of methylal devices brings more space for methanol demands. The chain of methanol-formaldehyde-methylal looks stable and has good demand support. The demands are increased for methanol and formaldehyde plant enterprises of overcapacity. However, a series of market performance reflects the market space of methylal is very small, and the chain of methanol-formaldehyde-methylal chain will be at the risk of out of control.

Thursday, September 5, 2013


Dimethylformamide (DMF) is an organic compound that is used as a solvent for many products, including lacquers, pigments and dyes. Known as a volatile organic compound (VOC), DMF can endanger both humans and wildlife, but the threat is regarded as minimal because it does not occur in nature and isn't encountered by humans outside of occupational settings. Dimethylformamide is not stable when strong acids or bases are around it, and it hydrolyzes back into its original state of dimethylamine and formic acid. According to the Material Safety Data Sheet (MSDS), dimethylformamide is hazardous to health, flammable, reacts to skin on contact and poses a minimal threat of reacting with other chemicals.
Recently we showed how crystallization in microemulsions could lead directly to the most stable polymorph, thereby leapfrogging Ostwald’s rule of stages. Here we consider in more details the crystallization of mefenamic acid from dimethylformamide microemulsions. Crystallization of mefenamic acid from bulk DMF has previously been shown to produce only the metastable Form II irrespective of the supersaturation or temperature.
Dimethylformamide is a polar (hydrophilic) aprotic solvent with a high boiling point. It facilitates reactions that utilizes polar mechanisms, such as SN2 reactions. Dimethylformamide can be synthesized from methyl formate and dimethylamine or by reaction of dimethylamine with carbon monoxide. Dimethylformamide is not stable in the presence of strong bases such as sodium hydroxide or strong acids such as hydrochloric acid or sulfuric acid and is hydrolyzed back into formic acid and dimethylamine, especially at elevated temperatures.
There are several ways to form dimethylformamide, all of which involve the use of dimethylamine. For smaller production runs, dimethylamine is catalyzed with carbon monoxide and methanol or with methyl formate. In larger, laboratory-scale productions, formic acid and dimethylamine react together to create this solvent.
In contrast, we show that stable Form I can be produced from DMF microemulsions provided the lowest supersaturations that can achieve crystallization are used; these correspond to initial supersaturations that are significantly higher than those commonly used in bulk solution crystallizations, owing to the large decrease in supersaturation that occurs when a nuclei grows in a 3D-nanoconfined droplet. Increasing the supersaturation above the minimum required for crystallization leads to increasing proportions of metastable Form II crystals.
As a solvent, or a chemical that mixes with other liquids, dimethylformamide is used in the formation of many products that require a strong chemical reaction. Its high boiling point leaves it with low evaporation potential, so it will not quickly dissipate when used with other chemicals at high temperatures. Many plastics and curing processes, such as the curing done to leather, need this chemical to complete the product or process. It also can be used to break down many organic compounds.
Dimethylformamide is a neutral compound, so it does not react very well when paired with a strong acid or base. A strong base would be a compound such as sodium hydroxide, and a strong acid would be something such as sulfuric acid. When a base or acid is paired with this compound, it will revert to its two original components. This reverting process is increased if placed in a high-temperature vat.
Co-exposure of noise, DMF and TOL can affect the ambulatory blood pressure and heart rate among synthetic leather workers. Noise exposure may have obviously higher effect than chemical exposure.
Dimethylformamide is a VOC, meaning it is dangerous for humans and wildlife. It is not made in nature and isn't encountered outside certain work settings, so it is not regarded as an especially hazardous compound. Testing has shown that DMF can easily and quickly transfer from dirt to groundwater and will quickly spread through any body of water. Dimethylformamide also has been shown to cause cancer and chronically affect organs such as the lungs and heart.
The MSDS, which grades all compounds on a scale of 0 to 4 with 4 being a serious hazard, shows DMF to be a hazard. The worst risk is contacting or touching the chemical, which is rated as a 3. Both health and flammability risks earn a 2; DMF also must be stored away from high temperatures. The reactivity level is only 1, so it should not react with other compounds in an adverse way.
This article is from http://www.hiseachem.com/news/Dimethylformamide.htm .