A method of preparing n-octacosane in the steps of:
(1) take 2773 g (10 mol) of brominated n-tetradecane and set aside;
(2) Weigh 241.5 g (10.5 mol) of sodium metal and cut it into small thin strips measuring about 1×3 cm2, set aside;
(3) in the reaction kettle put 50g bromine n-tetradecane as well as 20g sodium metal, stirring to warm up to 80 , withdraw the heat source, relying on the reaction heating, and maintained at 120 , constantly adding the remaining bromine n-tetradecane dropwise, and add sodium metal, to maintain a slight reflux state, the addition of the material is completed, the control of the temperature of 160 , the constant temperature for 2 hours;
(4) sequentially add 400 g of 95% ethanol reaction after adding 1000 ml of water, divided into organic matter, water washing to neutral, dried with anhydrous magnesium sulfate, distillation to collect 140 / 1 mmHg before the fraction, the remaining fraction washed with concentrated sulfuric acid to light yellow, washed with water to neutral, drying the proceeds of benzene with repeated purification three times, drained, to obtain the white crystalline eicosanoctadecane as 1.38 Kg, mp60-62 . Said brominated n-tetradecane of sodium metal molar ratio of 1:1.01.
