The Synthesis Process Of A New Sweetener-neotame

Neotame is a novel dipeptide sweetener,which has advantages of high-intensity of sweet,clean sweet taste,high-safety and non-nutritive.It is the highest rank of synthesized sweeteners up till now,which demonstrate its borad prospects.Therefore,it is very important to study the synthesis process of neotame.First,3,3-dimethylbutyraldehyde as a key intermediate was synthesized from terbutyl alcohol as a start material via four-step reactions.The parameters in the process for the synthesis of 3,3-dimethylbutyraldehyde were investigated and the optimal reaction conditions were determined.In the first step,the molar ratio of terbutyl alcohol to concentrated hydrochloric acid was 1:2,the reaction temperature was 25?,and the reaction time was 25 minute.Under the optimal reaction conditions,the yield of tert-butyl chloride reached 88.6% with a purity of 96.0%.In the second step,the mass ratio of catalyst to tert-butyl chloride was 1:40,the feeding rate of ethylene was kept of 200 mL/min,the temperature was maintained at-20?,and the reaction time was 280 minute.The yield of 1-chloro-3,3-dimethylbutane is 70.4%.In the third step,the hydrolysis was performed at 100? in the potassium hydroxide solution of 2.5 mol/L for 24 hours.The yield of 3,3-dimethyl-1 butanol reached 75.4% under theses conditions.In the fourth step,the mass ratio of 3,3-dimethyl-1-butanol to 4-OH-TEMPO was kept to be 29.1:1,and the mass ratio of 3,3-dimethyl-1-butanol to potassium bromide was 8.5:1.The yield of 3,3-dimethylbutyraldehyde reached 89.7% with a purity of 99.5% when the reaction was run under these loading ratio of reactants at temperature 35? for 15 hours.The self-synthesized 3,3-dimethylbutyraldehyde was employed to react with aspartame to afford neotame.The effects of reaction parameters including reaction temperature,molar ratio of raw materials,Pd/C loading and reaction time on the synthesis of neotame were investigated.After a series of experiments,the optimal conditions for the synthesis of neotame were obtained,which are the molar ratio of 3,3-dimethylbutyraldehyde to aspartame of 1.1:1,the mass ratio of catalyst to aspartame of 3:200,reaction temperature of 40?,and reaction time 15 hours.Under the optimal conditions the yield of neotame reached 70.2%.