Sodium methoxide is a dangerous chemical that is corrosive and flammable. It is mainly used in the pharmaceutical industry and as a condensing agent, chemical reagent, and catalyst for edible oil treatment in organic synthesis. Soluble in methanol and ethanol, decomposes into methanol and sodium hydroxide when exposed to water, and decomposes in air above 126.6°C. Insoluble in benzene and toluene.
Sodium methoxide products come in two forms: solid and liquid. The solid is pure sodium methoxide, and the liquid is a methanol solution of sodium methoxide. The sodium methoxide content is 27.5%-31%.
Uses of sodium methoxide
Sodium methoxide is widely used in spices, dyes and other industries. It is mainly used as a condensing agent, a strong alkaline catalyst, and a methoxylating agent for the preparation of vitamin B1 and A, sulfadiazine and other drugs. A small amount is used in pesticide production. It can also be used as a catalyst for processing edible fats and oils (especially lard). In addition, sodium methoxide can also be used as an analytical reagent.
Preparation method of sodium methoxide
1. Alkaline production process Alkali sodium methoxide is obtained by the reaction of methanol and sodium hydroxide. Its reaction formula is as follows:
CH3OH + NaOH – CH3ONa + H2O
(1) Preparation of methanol alkali solution
Crush the solid sodium hydroxide, add it to the alkali-dissolving pot containing methanol (99.8%) in proportion, and start Use a liquid caustic soda circulating pump to control the temperature below 70°C to dissolve sodium hydroxide. When the content reaches 20%-23%, cool it down to 40°C, pour it into a sedimentation tank, and let it stand for 12 hours for later use.
(2) Preparation of sodium methoxide
Pour water vapor into the interlayer of the evaporator and reaction tower for heating, control the temperature at 85-100°C, and add anhydrous methanol to the evaporator at a flow rate of 180L/h. At the same time, the methanol alkali solution is added from the top of the reaction tower at a flow rate of 25kg/h. The methanol gas containing 2% moisture produced by the reaction is evaporated from the top of the reaction tower and enters the purification distillation tower to separate the water and turn it into anhydrous methanol. recycle. The temperature at the bottom of the reaction tower (i.e. the vaporizer) is controlled at 65-70°C. Check that the material at the bottom of the tower contains 27%-31% sodium methoxide and less than 1% free alkali. The product is obtained with a yield of 86% (using sodium hydroxide count).
The consumption quota of this process is as follows: methanol (95%) 973kg/t, sodium hydroxide (99.5%) 209kg/t.
2. Metal production process
Using metallic sodium and methanol as raw materials, an intermittent production process is used to carry out chemical reactions to produce sodium methoxide methanol solution. The reaction formula is as follows:
2CH3OH + 2Na–2CH3ONa + H2↑
This production process is mainly divided into four parts: (1) Feeding process, pump industrial methanol to the methanol metering tank, and 120kg of metallic sodium is put into the reaction kettle; (2) Nitrogen replacement process, close the feeding and venting valves, introduce nitrogen into the reaction kettle, so that the pressure gauge index reaches 0.1MPa, open the venting valve to relieve pressure, repeat three times and then return to the venting valve. Keep it open and continue to feed nitrogen; (3) Reaction process: Pour cooling water into the condenser, immediately add methanol through the methanol metering tank (pay attention to the methanol addition speed), and react. Stop feeding nitrogen after 5-10 minutes of reaction. Continue to add methanol, meter in 820kg of methanol within 2-3 hours, close the methanol feeding valve, and continue the reaction for 2-3 hours until no bubbles are generated in the reaction solution; (4) In the blending process, add the product to the blending storage tank, take samples for analysis, and blend To the required concentration, fill the barrel.
Market Development Status
As a mature chemical product, sodium methoxide has been produced in my country for decades. The overall price is higher in the south and lower in the north. The selling price in southwest China is around 4,500 yuan per ton, and in Shandong, it is around 0 yuan per ton. At present, the domestic market has a large demand for sodium methoxide products produced by the metal sodium method. Since the sodium methoxide products produced by the metal sodium method have low free alkali content and have better catalytic activity, their market usage is on the rise.
At present, the total supply and demand of the domestic sodium methoxide market is generally balanced, but there are also the following characteristics: most sodium methoxide users with relatively large demand have their own production companies; liquid sodium methoxide production equipment is spread all over the country. Solid sodium methoxide production equipment is relatively concentrated; liquid sodium methoxide products have both alkali and metal production processes, with the majority being metal process; sodium methoxide products are produced based on sales; there is an imbalance of supply and demand in some markets.
