Process Research Of The Preparation Of Several Quinone Compounds By “Out-slot Type” Indirect Electrochemical Oxidation

As a kind of important fine chemical intermediates,quinone compounds are widely used in medicine,pesticide,veterinary medicine,perfume and dye,as well as new organic functional materials.This paper adopts "out-slot type" indirect electro oxidation process,using the metal redox couple Ce⁴⁺/Ce³⁺ as medium,using the Ce⁴⁺ in the electrolyte to oxidation aromatic hydrocarbon substrate naphthalene,1-nitro naphthalene and anthracene to synthesis target quinone intermediates,includes 1,4-naphthoquinone,5-nitro-1,4-naphthoquinone and 9,10-anthraquinone.End of the reaction,Ce⁴⁺ in electrolyte will be converted into invalid Ce³⁺,invalid Ce³⁺ will be regenerated on the anode plate of electrolytic cell through the method of electrochemical oxidation.As a result,the process of indirect oxidation of aromatic hydrocarbon substrate to prepare quinone intermediates can be divided into electrolytic oxidation and substrate oxidation.In this paper,the single factor control method is used to study the electrochemical oxidation and the substrate oxidation,determined.the optimum reaction conditions.The optimum conditions of electrolytic oxidation: frame electrolytic cell by using polypropylene material,using Nd-SnO2-Sb composite coating DSA mesh electrode as electrolytic anode,using 316 L stainless steel mesh electrode as electrolysis cathode,using Nafion551 selection ion exchange membrane as membrane material,the effective area of the electrode plate is 0.02m²,electrode spacing is d=5mm,the concentration of electrolyte is C?Ce ??= 1.0mol/L?C???=3.0mol/L,electrolytic temperature is t=40?,the current density is J=300A/ m²,the electrolyte flow rate is V=0.03m/s.When the conversion rate of Ce³⁺ in the electrolyte was controlled at 80%,the current efficiency was still greater than 80% after the electrolyte was applied for a period of 20 times.The optimum conditions of oxidation naphthalene to synthesis 1,4-naphthoquinone: electrolyte concentration was C(Ce⁴⁺)=0.6mol/L,C?acid?=3.0mol/L,the raw material molar ratio was n(Ce⁴⁺):n?naphthalene?=6:1,using n-heptane as solvent,organic phase naphthalene concentration was 0.2M,reaction temperature was 50?,reaction time was 15 min.Under the optimum reaction conditions,the conversion of naphthalene was 99.6%,the selectivity of 1,4-naphthoquinone was 98.1%,the purity of crude was98.8%,and the yield was97.7%.The optimum conditions of oxidation 1-nitro naphthalene to synthesis 5-nitro-1,4-naphthoquinone: electrolyte concentration was C(Ce⁴⁺)=0.8mol/L,C?acid?=3.0mol/L,the raw material molar ratio was n(Ce⁴⁺):n?1-nitro naphthalene?=8:1,using n-heptane as solvent,organic phase 1-nitro naphthalene concentration was 0.2M,reaction temperature was 70 ?,reaction time was 90 min.Under the optimum reaction conditions,the conversion rate of 1-nitro naphthalene was 98.6%,the selectivity of 5-nitro-1,4-naphthoquinone was 98.4%,the purity of the product was98.7%,and the yield was97.0%.The optimum conditions of oxidation anthracene to synthesis 9,10-anthraquinone: electrolyte concentration was C(Ce⁴⁺)=0.5mol/L,C?acid?=3.0mol/L,the raw material molar ratio was n(Ce⁴⁺):n?anthracene?=5:1,using n-heptane as solvent,organic phase anthracene concentration was 0.2M,reaction temperature was 30?,reaction time was 5min.Under the optimum reaction conditions,the conversion of anthracene was 83.2%,the selectivity of 9,10-anthraquinone was 94.6%,the purity of the product was98.5%,and the yield was78.7%.The experimental results show that the "out-slot type" indirect electro oxidation process can sustainable utilize cleaning electric energy to synthesis the target quinone intermediates,effectively reduce the use of chemical reagent,to avoid the traditional chemical oxidation process produced environmental pollution,high production cost and low product purity.The "out-slot type" indirect electro oxidation process has broad application prospects.