Study On The Synthesis Of 3, 3-dimethyl-1, 5-dioxa-spiro[5.5]undecan-9-one

3,3-Dimethyl-1,5-dioxa-spiro[5.5]undecan-9-one is an exceedingly useful bifunctional synthetic intermediate and has been widely used in synthetic organic chemistry such as pharmaceuticals and liquid crystal materials. After compared the existing synthetic methods, the synthesis of 3,3-dimethyl-1,5-dioxa-spiro[5.5] undecan- 9-one by 1,4-cyclohexane-dione and neopentyl glycol with acid-catalyst was chosen to be studied.Ascertainment of main factors for sulphuric acid catalyst use orthogonal test. The experimental results show that, the reaction conditions optimized are the reaction temperature 25℃, the reaction time 30min, the mole ratio of neopentyl glycol to 1,4-cyclohexanedione 1:1.2, methylene chloride reagent concentration 1.125mol·L-1 and the molar mass of catalyst is equal to 10% of feedstocks. Under the above conditions, the yields of monoketal is 62.9%. On this basis, the catalytic reaction kinetics by sulfuric acid was also studied. The apparent reaction order of the reaction, neopentyl glycol and 1,4-cyclohexane- dione is 2, 1 and 1, respectively.Considering the demands of the green chemistry, solid acid catalysts have been studied. For the purpose of comparison, several different ion-exchange resins are selected and find that the catalysis of NKC-9 is better than the others. The condensation reaction of 1,4-cyclohexanedione with neopentyl glycol by using NKC-9 macroporous resin as catalyst is firstly studied. The factors of the effects on the reactions are examined. The results showed that at 25℃, in dissolvent of dichloromethane, reagent concentration is 1.3mol·L-1, the weight of catalyst is equal to 15.4% of feedstocks, reaction mixture is stirred for 110min, under which the conversation rate of neopentyl glycol is 94%, the yield of monoketal can reach to 74.6 %. Compared with using sulfuric acid as catalyst,taking NKC-9 as catalyst make the procedure to be a green productive technology with higher yield (the yield of monoketal is increased from 62.9% to74.6%), process simplification, no corrosion to facilities, simple post treatment and it may reuse for many times. The product will be characterized by IR, 1HNMR and 13CNMR.