Preparation Of Cyclohexylcarboxaldehyde And Cyclohexanecarboxylic Acid From Cyclohexene

Cyclohexyl formaldehyde,as an important organic synthesis intermediate,has important application value in pesticide,medicine and some organic synthesis.In the traditional production process,due to the limitations of catalyst cost and preparation conditions,it has a certain influence on industrial production.Cyclohexyl formic acid,a downstream product of cyclohexyl formaldehyde,has also been widely used in medicine,petroleum,rubber and other fields.The oxidation of cyclohexylcarbaldehyde to cyclohexylformic acid prolongs the production chain of cyclohexene and has a positive effect on its industrial application.In this paper,hydroformylation of cyclohexene was studied from two routes of metal/phosphine complex and nano-metal particles.The influence of various reaction conditions on the whole reaction under different routes was studied,and the interactions between factors were analyzed by combining response surface analysis.The corresponding characterization was performed by ¹³C-NMR,¹H-NMR,³¹P-NMR,TEM and XPS.In addition,aldehydes were oxidized with different additives by using cyclohexylcarbaldehyde as a raw material and hydrogen peroxide as an oxidizing agent.The main research contents are as follows:（1）The prepared phosphine ligands were characterized by ¹³C-NMR,¹H-NMR,and ³¹P-NMR,and compared with MPEG-350 to determine the characteristic state of the ligand.（2）In experiments catalysing the hydroformylation of cyclohexene with metal/phosphine complexes,the single metal salt RhCl₃·3H₂O has the best effect.Throughdopingwithdifferentsalts,itwasdeterminedthat m（RhCl₃·3H₂O）:m（Ru Cl₃·3H₂O）=18.5:1 was the best,and was better than a single salt.From single factor experiments,the effects of reaction temperature,reaction pressure,phosphine ligand addition amount and reaction time on the reaction were investigated,and the optimal reaction conditions under single factor were determined.On this basis,response surface experiments with three factors and three levels of reaction temperature,reaction pressure,and phosphine ligand addition were designed to analyze the influence of interactions between the three factors on the reaction.The optimum process conditions were determined as follows:phosphine ligand addition P=0.09g,synthesis gas pressure p=5.3 MPa,reaction temperature T=122°C.At this point,the conversion of cyclohexene is greater than 99%.（3）The hydrated chloride salts of yttrium,barium and cobalt were reduced by hydrogen reduction.Different nanoparticles were prepared using PEG-4000 as a stabilizer.Combined with the hydroformylation reaction,the collocation of chlorides in this reaction was determined,ie,m（Co Cl₂·6H₂O）:m（RuCl₃·3H₂O）=14:1,that is,n（Co）:n（Ru）=12.74:1.The prepared nanoparticles were characterized by XPS and TEM.The surface metal valences were determined.The particle size was mainly distributed between 1.5 and 3.5 nm,and the average particle size was 2.53 nm.（4）In the case of nanoparticle-catalyzed hydroformylation of cyclohexene,the effects of the reduction temperature,the hydrogen inlet pressure,the synthesis gas pressure in the hydroformylation stage,and the reaction temperature on the reaction were investigated in a single-factor experiment.And determined the best reaction conditions under single factor.On this basis,response surface experiments with three factors and three levels of hydrogen pressure,hydroformylation pressure and reaction temperature were designed to analyze the influence of interactions between the three factors on the reaction.The optimum process conditions were:reduction pressure 6.25MPa,synthesis gas pressure 5.75 MPa,hydroformylation temperature 128°C.Under the experimental conditions,the yield of cyclohexylcarbaldehyde was 97.9%.The catalyst has a high activity and stability.（5）Using cyclohexylcarbaldehyde as a raw material,experiments were conducted with 30%hydrogen peroxide and oxygen as oxidants.Among them,the hydrogen peroxide route,by adding different additives,changing the amount of additives,reaction temperature,hydrogen peroxide addition amount to examine the oxidation effect of cyclohexyl formaldehyde.And with these three factors,the response surface experiment was designed to analyze the influence of each factor and the interactive influence.The optimum conditions were as follows:the amount of potassium carbonate added m（K₂CO₃）=1.15 g,the amount of hydrogen peroxide added V（H₂O₂）=10 mL,T=63°C,and the corresponding yield of cyclohexylcarboxylic acid was 98.6%.In the oxygen catalytic oxidation route,the reaction temperature is changed by comparing different catalysts,adding different proportions of cocatalysts.As well as designing the tower reactor,the oxygen flow rate and the ratio of the height to the diameter of the reaction liquid are changed to carry out the oxidation reaction.The optimum conditions were as follows:mass ratio of main catalyst to cocatalyst m（C）:m（P）=1:4,reaction temperature T=80°C,oxygen flow rate 80mL/min,heighttodiameterratio12:1.Thecorrespondingyieldof cyclohexylcarboxylic acid was 95.9%.