年产1200吨NPM工艺设计+文献综述(4)
2 Literature Review
Nitro anisole is also known for P—nitro anisole. Used as intermediates in organic synthesis. It is also for the production of amino anisole, blue salt, vitamin B, etc. On the yield and quality Nitro anisole directly affects on the yield and quality aminoanisole. Therefore, many scholars have long carried a lot to explore its synthesis.
3 Route selection of raw materials
Nitroanisole is important for the synthesis of pharmaceutical raw materials, such as organic dyes and pigments. Always synthetic routes are mainly three kinds: nitro phenol and methyl chloride reaction, anisole nitration and nitro chlorobenzene and sodium methylate reaction. The first two methods because the synthetic route length, separation process is complex, and the tight supply of raw materials. It is not suitable for industrial production. At present, China is using nitro chlorobenzene law. In the presence of a large and solid sodium hydroxide in methanol autoclave synthesis NPM about 10h-13h. But this process there is a large methanol consumption, long reaction time, the reaction yield is low, production capacity byproducts, environmental pollution and other issues. According to the above-mentioned disadvantages of the process, the use of phase transfer catalysis synthesis of NPM, in order to overcome the current process harsh reaction conditions, hydrolysis multi-product, wastewater volume and other shortcomings, so the use of phase transfer catalysis can create more social, economic and environmental benefit.4By studying and comparing different process routes to determine the order of the nitro chlorobenzene, methanol and sodium hydroxide as raw material, TEBAC as phase transfer catalyst synthesis process route for Nitroanisole at atmospheric pressure.
4 Design basis and principles
Nitroanisole can be used for the synthesis of blue salt VB, maroon-based GP, Naphthol AS dyes and pharmaceutical products. It is important pharmaceutical intermediate and dye. Its excellent quality, inferior quality depends on the nitroanisole. Preparation Nitroanisole of mainly the following methods: nitro chlorobenzene under pressure methoxy, nitro chlorobenzene under pressure methoxy, use of a phase transfer catalyst for nitro chloro methoxylated benzene. Since the first two methods operate more cumbersome, product yield and quality is not high, and phase transfer catalysis method does not require special equipment, does not require expensive anhydrous or aprotic solvent and mild reaction conditions, simple operation, fewer side effects. In recent years, phase transfer catalysis Preparation of ethers, have been reported in the literature a lot. Ether synthesis phase transfer catalyst, the use of quaternary ammonium salts, quaternary phosphonium salts, crown ethers and linear polyoxyethylene compounds. 7But emulsification quaternary obvious to the isolation of the product, purification will bring some difficulties; crown ethers expensive and toxic, the application is also subject to certain restrictions. Therefore it becomes a research hotspot in recent years.
The basic principle of phase transfer catalysis reaction using the molecular structure of the catalyst is soluble in both the aqueous phase, the organic phase and soluble functional group. The nucleophilic substitution reaction, in the presence of a small amount of water, the catalyst can be a nucleophile with an aqueous phase to form an ion pair, so that the original is not soluble in the organic phase into the organic nucleophile easily participate in the reaction phase.
5 Technical feasibility
This design uses a three-phase catalytic synthesis method for Nitroanisole. The reaction mechanism for the phase transfer reaction mechanism. For the selection of optimal production conditions, by varying the ratio of different nitro-chlorobenzene and methanol, sodium hydroxide concentration, type of catalyst, amount of catalyst, the holding time to determine the best operating conditions.
When changing only the control of the remaining conditions constant concentration of sodium hydroxide, were used at a concentration of 30%, 35% and 40% sodium hydroxide solution for testing. The experimental results show that when the concentration of 35% sodium hydroxide solution, the experiment yields the highest nitroanisole therefore selected 35% sodium hydroxide solution concentration optimum pH.
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