Method for preparing n-tetradecane, n-heptadecane and n-eicosane at one time

Abstract

The invention relates to a method for preparing n-tetradecane, n-heptadecane and n-eicosane at one time, which comprises the following steps of: preparing raw materials comprising bromoalkane and sodium metal for later use; adding bromoalkane mixed liquid and the sodium metal into a reaction kettle, stirring the solution and heating the solution to 80 DEG C, maintaining the temperature between 120 and 140 DEG C, controlling the temperature to be 140 to 160 DEG C after the rest material is completely added, and keeping constant temperature for 2 hours; and adding ethanol and water into the solution in turn, separating out organic substances and washing the organic substances to be neutral by using water, drying the organic substances by using anhydrous magnesium sulfate, collecting fractions by distillation, and collecting n-tetradecane, n-heptadecane and n-eicosane finished products through water distillation columns according to different boiling points. A strong oxidant such as concentrated sulfuric acid or acid potassium permanganate used in the preparation method has oxidation effect on unsaturated organic substances and alcoholic impurities in the reactants and removes unsaturated hydrocarbons to achieve the effect of eliminating the impurities, the content of the normal alkanes reaches 96 to 98 percent, and the purity of the finished products is improved.

Description

Technical field [0001] The invention belongs to the field of normal alkanes in chemical reagents, and relates to a preparation method of alkanes, in particular to a preparation method for preparing n-tetradecane, n-heptadecane and n-eicosane at one time. Background technique [0002] As one of the key components of diesel fuel, low temperature improvement, and environmentally friendly liquid fuel composition, n-alkane has been widely used. At the same time, n-alkane monomer also plays an important role in the analysis of geology, crude oil, atmospheric particulate matter and organic matter. Important role. At present, due to the different sources of n-alkanes, the composition of various n-alkanes is different, resulting in different degrees of product quality. Some special n-alkane monomers are needed to adjust the composition ratio of n-alkanes to make The quality can be maximized. [0003] According to the search, the types of preparation methods that currently exist for n-alka...

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Problems solved by technology

[0003] According to the search, the types of n-alkane preparation methods that currently exist are as follows: 1. The mixture of n-alkane is prepared by dewaxing molecular sieve or urea, and then sub-stage freezing is carried out to separate the n-alkane monomer. The most advanced processes include the molex process of Vop Company and the IVDW process developed by my country; 2. Adopt Wurtz reaction to prepare symmetrical normal alkanes; 3. Use iodoalkane reduction method; 4. Use petroleum ether, n-hexane, n-heptyl Although the above methods can prepare corresponding n-alkane monomers, there are certain problems in each method: as the first method, the process conditions are relatively complicated, and the requirements for certain equipment and materials are relatively high. The investment scale is relatively large, and it is only suitable for large-scale petrochemical production; the second method is suitable for symmetrical even-numbered alkanes, and the product needs to be extracted repeatedly with ether, and the raw materials above the octadecyl carbon chain are not easy to obtain; the third and fourth methods are dangerous to operate High resistance, petroleum ether is very easy to erupt in the violent reaction between metal sodium and halogenated alkanes, low safety factor and high cost