Study On Synthesis Of1,4-Naphthoquinone By Oxidation Of1-Naphthylamine

1,4-Naphthoquinone is an important raw material in the fine chemical industry. It can be used as a key intermediate in the synthesis of dyes, pharmaceuticals, pesticides, fragrances, plasticizers, new pulp paper additives and so on. It is a good antifungal agent, preservative and non-systemic fungicide, and can be manufactured as bilge coating, electronic replication material and deodorant. The production of1,4-naphthoquinone still mainly uses traditional liquid-phase oxidation method which is in small production scale, low yield and serious environmental pollution. In this thesis, a new type of liquid-phase oxidation method to improve the traditional production process of the1,4-naphthoquinone is researched. Fenton’s reagent, H2O2, manganese ore powder, NaClO, HNO3and mixed acid have been studied as oxidant in the synthesis of1,4-naphthoquinone by oxidation of1-naphthylamine. The effects of the oxidation time, reaction temperature, concentration of the oxidant, molar ratio of1-naphthylamine to the oxidant etc. on the product yield were investigated.In the selection of different catalysts for catalytic oxidation, we found MnSO4was the best catalyst in the Fenton’s reagent. We have avoided the use of environmentally polluting organic solvents with simple process under the mild reaction conditions. At a temperature of80°C, reaction time3h, the product1,4-naphthoquinone can yield up to45.4%.When using H2O2as oxidant, essentially H2O2has been transformed into the peracetic acid which oxidated1-naphthylamine later in the solvent of glacial acetic acid. The method using green chemistry reagents H2O2as oxidant to synthesize1,4-naphthoquinone without catalyst is easy to control under mild reaction conditions without environmental pollution, and the product yield can be as high as52.2%.The cost of oxidation using manganese ore powder as oxidant is low-priced and the raw materials are easy to get. It was found that manganese ore powder being processed in mass fraction40%sulfuric acid was more active, and the product yield can reach up to59.8%with a simple post-processing. So this process is easy to industrialization.When using NaClO as the oxidant, the pH of the solution plays a decisive role in the oxidation-reduction potential of the whole system. The reaction process is difficult to control and the post-processing is troublesome. Moreover, the purity of the product obtained is not high.Using inorganic acid (HNO3and mixed acid) as the oxidant, the reaction is very intense, dangerous and can produce polluting gases NOx. Therefore it is not easy to industrialization.