Tungsten Trioxide Compounds Adipic Acid

Adipic acid is also known as fat acid, it is an important organic dicarboxylic acid, it can occur salt, esterification, amidation reaction, and can compound the diamine or diol condensation into high molecular polymer. Adipic acid slightly solubles in water, its solubility has large changes in water. When the solution temperature from 28 ℃ rises to 78 ℃, the solubility can increases to 20-fold. Adipic acid is dicarboxylic acids of great significance in the industry; it has an important role in chemical production, organic synthesis industry, medicine, manufacturing, and other lubricants. Adipic acid is mainly used as raw material for nylon and engineering plastics, but also for the production of esters products, also used as a raw material of polyurethane elastomer, a variety of food and beverage acidulant, and its role may be worth citric acid and tartaric acid. Adipic sour is soft and durable in a wide concentration range of pH change; it is the preferred pH modifier.

Steps
Adding 0.5806g tungsten trioxide, 44.5ml hydrogen peroxide into a 100ml reaction flask. Stirring at room temperature for 10min, then adding 10.5ml cyclohexene (about 100ml, hydrogen peroxide / cyclohexene about 4.4 mole), controlling oil bath heating temperature at 120 ℃, the initial reaction temperature is 75-80 ℃, the latter part of is 95-100 ℃. After completion of the reaction at 85 ℃ under reduced pressure, the separated catalyst becomes tungsten trioxide, and the resulting solution was filtered and allowed in an ice water bath 0.5h. We can obtain adipic acid when the reaction flask is precipitated as adipic acid crystals by vacuum filtration at room temperature.

Conclusions
1. The results shows that the conditions of optimal reaction are: the amount of tungsten trioxide is 5.0mmol, the reaction time is 6h, the rate of adipic acid separation reaches the maximum 75.4 %, and the purity of adipic acid purity is 99.8%.
2. When the amount of tungsten trioxide is 1.25mmol in the solution, there are not products in active centers. With the increasing of the amount of catalyst, an acidic solution is higher; the corresponding increases in the number of active centers.