Study On The Synthesis Of Dodecanol Ester

Dodecanol ester which is called 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate is an emerging green additive, widely used in paint industry. Compared with other additives, dodecanol ester has many advantages such as: good compatibility, less dosage, low film formation temperature, good leveling and color development, low freezing point, hydrolytic stability, low toxicity and so on.The production of dodecanol ester can be synthesized by isobutyraldehyde with alkali as catalyst. The main reactions involved in the process are aldol and cannizzaro reactions. Within the temperature range from 20 ℃ to 100 ℃,we have deeply thermodynamic calculations of the production of dodecanol ester through a variety of group contribution methods. The results show that: the reaction of 2,2,4-trimethyl-3-hydroxy-pentanal with isobutyraldehyde as raw material via aldol condensation reaction is an exothermic reaction, the further cannizzaro reaction of pentanal and isobutyraldehyde to 2,2,4-trimethyl-1,3-pentanediol and isobutyrate is an endothermic reaction, the main reaction of three isobutyraldehyde synthesizing 2,2,4-trimethyl-1,3-pentanediol diol monoisobutyrate is exothermic; over the entire temperature range aldol reaction and the main reaction can occur spontaneously, but cannizzaro reaction spontaneous at more than 40 ℃; thermodynamically speaking, heating temperature is not conducive to aldol condensation reaction and the main reaction but in favor of cannizzaro reaction.Research on conventional catalytic reaction system are as follows: the type of catalysts, heating way, optimizing of reaction conditions, separation, purification and characterization of the products and so on. Experimental results show that: in the catalysts of powdered sodium hydroxide, calcium hydroxide, the mixture of sodium hydroxide and calcium hydroxide,(mass ratio 7:3), sodium methoxide, sodium ethoxide, the solution of sodium methoxide and methanol, powdered sodium hydroxide is finally selected as the optimal catalyst, the warming mode is used one step only, optimization of reaction conditions is by orthogonal analysis of three factors and four levels. The final optimal conditions are as follows: the catalyst dosage is 2.50 %, the reaction temperature is 50 ℃, the reaction time is 4 h. Under these conditions, the catalytic effect is best with the yield of target product is 82.07 %. After taking off the aldehyde and vacuum distillation we get the product with purity of 99 %.The study on catalytic effect of immobilized catalysts is with sodium nitrate as the active component, molecular sieve such as γ-Al2O3, NaY, SBA-15 and activated carbon as the carriers. First, the catalyst supports are screened to determine the carrier of activated carbon, then the catalytic effect of activated carbon sizes, the impact of loading amount of sodium nitrite, the effect of catalyst dosage range, the effect of calcination time on the catalytic performance are explored, we also conduct repetitive experiments using the recovered catalysts. The results show that: under conditions of the reaction temperature of 50 ℃, reaction time of 6 h, calcination temperature of 800 ℃, calcination time of 3 h, the carrier is activated carbon of 60 mesh, the loading amount of sodium nitrate is 30 %, catalyst concent is 30 %, at these conditions the catalytic effect is the best with the yield of target product of 73.55 %, and after five reproducibility experiments the immobilized catalyst stability is well. After taking off the aldehyde and vacuum distillation we get the product with purity of 99 %.Through this study we determine the forms of conventional catalysts and supported solid catalysts and the reaction conditions, with these conditions we get a better response effect, so it can provide a foundation to achieving industrialization, and it is more conducive to actual production.