Research On Synthesis Of P-Hydroxybenzaldehyde And Its Application

As the national strategy of sustainable development, higher requirements were lodged, and the study on method of selective and efficient green synthesis has become one of the key areas in chemistry industry. p-hydroxybenzaldehyde has a wide range of applications in Pharmaceuticals, perfumes, pesticides and so on. So research on systhesis and application of p-hydroxybenzaldehyde is not only important in academic significance, but also has a broad application prospect.This dissertation includes four elements:1 Synthesis of p-hydroxybenzaldehydeReimer-Tiemann reaction has been systematically studied, the green, effective reagent and highly selective phase transfer catalyst can promote the yield and selectivity of abnormal Reimer-Tiemann reaction. First use of glycerol as the solvent, D301 resin as phase transfer catalyst, the yield of p-hydroxybenzaldehyde 71.8% and 95.2% selectivity can be achieved in unusual Reimer-Tiemann reaction. It’s a more suitable for industrial production.2 Synthesis of NitroxynilVeterinary drug Nitroxynil was synthesized by applying "One-pot" synthesis technology. p-hydroxybenzaldehyde as starting materials to react with hydroxylamine hydrochloride giving hydroxybenzonitril, then reacted with sodium periodate, potassium iodide and sodium chloride, without handling, direct synthesis of Nitroxynil by adding sodium nitrite. This new method provides short synthsis route, simple operation, low production cost, high yield and environment-friendly. It’s a effective green synthesis method.3 Synthesis of 1-Amino-2, 4-imidazolidinedione and benzenesulfonylα,β-unsaturated ketone applying solid phase organic synthesis.1-Amino-2, 4-imidazolidinedione was prepared in two ways: 1) Merrifield resin-supported benzaldehyde as starting materials to react with compound semicarbazide giving resin-supported semicarbazone. It was followed by ring formation with ethyl monochloroacetate in the presence of sodium ethoxide, then cleavaged with hydrochloric acid solution to give product. 2) Merrifield resin-bound aldehyde as starting materials to react with semicarbazide giving resin-supported semicarbazone, after cyclization and cleavage, giveing product. Cleavage from the polymer support were carried out by using 1 mol/L hydrochloric acid solution instead of trifluoroacetic acid. This method was convenient and environment-friendly .Merrifield resin-supported benzaldehyde as starting materials to react with acetone giving resin-supported ketone, then react with the bromide reagent Ph₃P⁺CH₂CH₂COOHBr₃^- to give resin-bound unsaturated ketone. It was followed by nucleophilic substitution reaction in the presence of Sodium benzenesulphinate, then cleavaged with trifluoroacetic acid to giveα,β-unsaturated ketone. The new method provide mild reaction conditions, simple work-up procedure and quantitative yields. It’s a effective green chemical synthesis method.4 Synthesis of Imidocarb DihydrochlorideThe synthesis of veterinary drug imidocarb dihydrochloride were improved in three ways: l)Imidocarb was synthesised use cheap benzaldehyde, lowering the cost of production; 2) In the reduction reaction, we use zinc powder instesd of iron powder as reducing agent, which can provide simple post-processing and good color of product; 3)In the condensation reaction, we use triphosgene replace phosgene, while DMF and CH₂Cl₂ mixture as reagent, which did not require salt formation reaction. The new method predi- gest synthetic route and reduce the cost of production.A new synthesis route was designed, which has two advantages: l)cleverly avoid the toxic 2-（3-nitrophenyl）imidazoline; 2) In the condensation reaction, ethylenediamine as reagent and the reaction medium at the same time, thus shortening the reaction time, improving the yield and reducing the cost of production. It’s a more useful new method in industry.