Use of solid phosgene

Compared to gaseous phosgene, solid phosgene has the following advantages: 1) It is safer to use and more environmentally friendly; it lacks the high toxicity of gaseous phosgene as well as the strong tear-inducing effect of diphosgene, and is treated merely as a general toxic substance. 2) Solid crystallization, easy to use, and accurate in measurement. 3) It can achieve a reverse addition reaction that is not possible with phosgene gas ； 4) Equivalent reaction, with high yield of reaction products. 5) It can be stored and transported. Properties of solid phosgene: Solid phosgene (BTC) I. Physicochemical properties Chemical name: Bis(trichlormethyl)carbonate, also known as trichlormethyl carbonate; its English name is Bis(trichlormethyl)carbonate, abbreviated as BTC, or trifosgene, or Carbonic acid bis-(trichlormethyl)ester, or Methanol trichloro-carbonate. Its CAS number is 32315-10-9. 　　 This product is a stable white crystal with a melting point of 78–82°C and a boiling point of 203–206°C. It has an odor similar to that of phosgene. Its molecular formula is CO(OCCl3)2, with a molecular weight of 296.75. The density of the solid form is 1.78 g/cm3, while the density in its molten state is 1.629 g/cm3. Its structural formula is: (for convenience, this substance is referred to as BTC.) Since one mole of BTC can produce three moles of phosgene under certain conditions, it is also called “triphosgene.” As it is in solid form, it is also known as “solid phosgene.” 　　 BTC is insoluble in water, but soluble in organic solvents such as benzene, toluene, ethanol, ether, chloroform, **furan, and dichloroethane. It decomposes when exposed to hot water and sodium hydroxide. BTC exhibits reactivity similar to phosgene; it can react with various compounds such as alcohols, aldehydes, amines, amides, carboxylic acids, phenols, and hydroxylamines, and can also undergo cyclization and condensation to form heterocyclic compounds. In short, BTC can completely replace the highly toxic phosgene and diphosgene in chemical reactions to synthesize related chemical products. II. Safety and Usage 　　 1. This product is a Class 2 organic toxin, with a CAS number of 32315-10-9. Its UN number is 2811. According to GB6944 classification standards for hazardous substances, it belongs to Category 6, with the code 61908 – Class 2 organic toxic substance. The special provisions applicable to it are 73. 　　 2. This product is extremely stable at room temperature; it should be packaged in a sealed container and stored in a dry, cool, well-ventilated place. It must not be stored together with alkaline compounds. 　　 3. When using or handling this product, the operator should wear plastic-coated gloves and a gas mask, and personnel should also stay as far upwind as possible. 　　 4. In case of eye irritation or skin contact, rinse with clean water; in cases of accidental ingestion or inhalation, the affected person should rest in peace and receive oxygen therapy. For severe cases, 20 ml of 20% atropine should be injected. 　　 When in use, it depends on the specific reaction system; generally speaking, if the system contains substances that can trigger its decomposition (organic amines, activated carbon, organic bases), no initiator is needed for the reaction to proceed smoothly. Otherwise, 1-5% (by weight of the product) of an organic base such as DMF or pyridine is added to the other phase (the reaction generally takes place in two phases: one phase is a solid phosgene solution, and the other phase is the substance that reacts with phosgene); the rate at which one phase is added to the other phase is controlled in order to regulate the speed of the reaction. Solvents for BTC include benzene, chloroform, dichloroethane, cyclohexane, etc. These solvents should not be substances that cause its decomposition, while the solvent in the other phase is preferably one that can induce its decomposition. III. Applications 1. In the field of pesticides, a range of carbamate pesticides can be produced, as well as urea-based herbicides such as isoproturon and metolachlor, herbicides like simazine, oxadiazon, and diuron. There are also insecticides such as chlorpyrifos, and antifungal agents such as difenoconazole ； Furthermore, a series of benzoylurea insecticides and sulfonylurea herbicides can also be produced. 　　2. In the pharmaceutical industry, it is used to produce the nitrile ester intermediate for the anti-ulcer drug cimetidine, the tetrachloroazetanol intermediate for the anti-infective drug cefazolin, the carbamate ester of ampicillin used in the synthesis of sleeping pills, the non-steroidal anti-inflammatory drug ambixocam, and antihypertensive drugs, among others ； It can also be used to synthesize the antibacterial drugs azlocillin, piperacillin, and cefoperazone, the antidepressant and analgesic drug carbamazepine, and the antiepileptic drug trimethadione ； Chlorzoxazone, a muscle relaxant, can also be produced. 　　3. In organic synthesis, acyl chlorides, halides, special aldehydes, and ketones can be prepared. 　　4. In the field of dyes, it can be used as a substitute for phosgene to produce various direct dyes, such as Direct Yellow, Direct Lightfast Red, as well as dye intermediates like alizarinol and red base GC. 　5. 4,4-Diphenyloxydiphenylmethane, obtained by reacting with diphenyl ether in the field of synthetic polymer materials, is an important intermediate for producing polymers. It can be used to create polyethers with excellent chemical and thermal stability, namely PEER. It can also be utilized to produce carbonates and block copolymers. Functionalized polystyrene, when reacted with corresponding amines, yields monobasic or polybasic isocyanates such as TDI and MDI, which serve as important monomers for synthesizing various polyurethanes. It can also be used in the synthesis of liquid curing agents such as diethyl azodicarboxylate, diisopropyl azodicarboxylate, and dibutyl azodicarboxylate, which are used in the production of sponge rubber and as rubber processing aids. 　　 In recent years, BTC has been successfully widely used in many areas as a new type of chemical raw material.

Regarding the handling of off-gases generated during the use of solid phosgene and during the removal of excess light and acid, especially in terms of safety issues, I would appreciate your advice

【When in use, it depends on the specific reaction system; generally speaking, if the system contains substances that can initiate its decomposition (organic amines, activated carbon, organic bases), no initiator is required for the reaction to proceed smoothly.】 Otherwise, 1-5% (by weight of the product) of an organic base such as DMF or pyridine is added to the other phase (the reaction generally takes place in two phases: one phase is a solid phosgene solution, and the other phase is the substance that reacts with phosgene); the rate at which one phase is added to the other phase is controlled in order to regulate the speed of the reaction. Solvents for BTC include benzene, chloroform, dichloroethane, cyclohexane, etc. These solvents should not be substances that cause its decomposition, while the solvent in the other phase is preferably one that can induce its decomposition. 】 What if another phase solvent causes decomposition and generates phosgene? How to handle security management? Even if there isn’t an excess of BTC, it can’t be guaranteed that the decomposed phosgene will react immediately, right? .

Multi-layer film absorption tower for absorbing exhaust gases

I would like to ask if there are any specific policy requirements regarding the production and use of solid phosgene

Those who need to produce solid phosgene, please get in touch. QQ2578609539