Research On Paired Electrosynthesis Of Benzaldehyde And Tetramethyl Piperidinol

Both benzaldehyde and tetramethyl piperidinol are important organic chemical products. Benzaldehyde is widely used in the field of medicine, perfumes, dyes, agricultural chemicals, used to synthesis substance such as phenylacetaldehyde, benzyl benzoate, lauryl aldehyde, lauric acid, light green, benzylidene aniline, benzalacetone Etc., itself can be also used as Spices Reconcile agent, Solvent of Cellulose resin,while tetramethyl piperidinol is an important intermediate for the synthesis of hindered amine light stabilizer (referred to as HALS). Both of they have good market prospects. At present, traditional methods of synthesis benzaldehyde include hydrolysis of toluene side-chain chlorination, oxidation of toluene by air, method of synthesising tetramethyl piperidinol is primarily catalytic hydrogenation of tetramethyl piperidone. Both benzaldehyde and tetramethyl piperidinol can be synthesized by conventional chemical methods and electrochemical methods,In all these methods there are problems such as the reaction process complex and difficult to control, serious environmental pollution, low product yield and purity hard to solve.While the electrochemical synthesis is a synthesis process of mild reaction conditions, green and efficient, undoubtedly the best choice for the future to synthesis benzaldehyde and tetramethyl piperidiol.Currently, research on electrosynthesis of benzaldehyde is primarily indirect electrochemical synthesis method toluene in acidic medium. While this paper will explore the possibility of synthesis of benzaldehyde in alkaline medium.First, in this paper nickel foam will be used as matrix to make a novel nickel oxyhydroxide electrode with wide range scan of voltage by cyclic voltammetry. Electrode catalytic performance tests show that catalytic activity of the novel nickel oxyhydroxide electrode improved significantly as to nickel foam electrode. Cyclic voltammetry at different scan rates tests show that electrooxidation process of benzyl alcohol is controlled by diffusion, catalytic mechanism shows that nickel oxyhydroxide electrode similar to indirect electrosynthesis process.Then, in the H-type membrane electrolyzer, nickel oxyhydroxide electrode as anode, zinc as cathode, in an alkaline medium we successfully synthesized benzaldehyde. The impact of the anodic solution group benzyl alcohol amount, NaOH amount, reaction temperature, current on the anode current efficiency was investigated. The optimum conditions of electrooxidation of benzyl alcohol to benzaldehyde show that:when the anodic solution group are benzyl alcohol amount 0.05mol, NaOH amount 1.0g,with reaction temperature at 25℃, current Strength is 0.3A, the current efficiency of the synthesis of benzaldehyde reached 89%.In the process of electrically synthesis of benzaldehyde above, the cathode reaction is hydrogen evolution, therefore current through the cathode side not actually effective used, which obviously waste. Research on process methanol electro-oxidation of benzene above to benzaldehyde electrochemical reduction and the preparation of the relevant literature tetramethylpiperidine alcohol discovery process, both the reaction conditions are similar, experiments show that the two can achieve pairing. Therefore, on the basis of the above experiment, this article will further explore the possibility of pairs of electrical benzaldehyde and tetramethylpiperidine alcohol.Based on optimum conditions of the electro-oxidation of benzaldehyde, in the H-type membrane electrolyzer, nickel oxyhydroxide electrode as anode, zinc as cathode,the impact of the amount four methylpiperidone, NaOH amount, ethanol concentration on current efficiency was investigated. The results showed that:when the amount of benzyl alcohol anode at 0.05mol, NaOH at 1.0g, tetramethyl piperidine at 0.02mol, NaOH amount 0.8g, ethanol concentration 30%, the reaction temperature 25℃, current 0.3A, the anode current efficiency is 85.16%, the cathode current efficiency is 67.05%, the total current efficiency can reach 150%. the efficiency of time and space of electosynthesis relative to monopolar electrical electosynthesis is greatly improved, also paired electrosynthesis can generate two kinds of fine chemical products, which significantly improved economic efficiency.