Brief discussion of difluoromethane
Difluoromethane, its molecular formula is\ (CH_ {2} F_ {2}\), it is a colorless gas at room temperature and pressure, and has a slight ether taste. This substance has unique characteristics in the field of chemistry and is widely used in many aspects.
Properties of mono- and difluoromethane
1. ** Physical properties **: The boiling point is about\ (-24.02 ^ {\ circ} C\), and the freezing point is\ (-136.0 ^ {\ circ} C\). The density is relatively stable under standard conditions, and the density is slightly higher in the gaseous state than that of air. Its critical temperature is about\ (113.3 ^ {\ circ} C\), and the critical pressure is up to\ (5.78MPa\). It is slightly soluble in water, but it is miscible with most organic solvents, such as ethanol, ether, etc.
2. ** Chemical properties **: Difluoromethane is relatively stable in chemical properties and is not prone to chemical reactions under general conditions. However, under the action of high temperature, high pressure or strong catalyst, it can participate in some specific reactions. For example, when there is a suitable catalyst, it can be substituted with chlorine gas to gradually generate derivatives such as chlorofluoromethane.
Applications of difluoromethane
1. ** Refrigeration field **: As a new type of refrigerant, difluoromethane has excellent refrigeration performance. Its ozone layer destruction potential (ODP) is almost zero, and its greenhouse gas emission potential (GWP) is relatively low, which meets environmental protection requirements. It is widely used in household air conditioners, commercial refrigeration equipment and other fields, and can efficiently realize heat transfer and achieve refrigeration purposes.
2. ** Use of foaming agent **: In the production of foam plastics, difluoromethane is often used as a physical foaming agent. It is easy to vaporize when heated, forming bubbles in the plastic matrix, so as to obtain foam plastics with porous structures, such as polystyrene foam used for building insulation, polyurethane foam, etc., to improve the thermal insulation performance of the material.
3. ** Aerosol propellant **: Because of its stable nature, low toxicity and good gasification performance, difluoromethane can be used as a propellant for aerosol products. For example, in hairspray, air freshener and other products, it can effectively spray the contents out of the container to ensure the normal use of the product.
Production of trifluoromethane and difluoromethane
1. ** Direct fluorination method **: Methane is used as raw material and directly reacts with fluorine gas under specific conditions to form difluoromethane. This reaction requires strict control of the reaction conditions. Because fluorine gas is extremely active, the reaction is violent and it is easy to generate a variety of by-products. Usually special catalysts and precise control of temperature and pressure are required to improve the selectivity and yield of difluoromethane.
2. ** Halogenated hydrocarbon fluorination method **: Chloromethane is used as the starting material, and hydrogen fluoride is substituted with hydrogen fluoride under the action of the catalyst, and chlorine atoms are gradually replaced with fluorine atoms to produce difluoromethane. This method is relatively easy to control and has a high yield. It is one of the common methods for industrial production of difluoromethane. The catalysts used are mostly metal halides, such as antimony trichloride, and the reaction is usually carried out in a reactor at a specific temperature and pressure.
