n-Heptane is a colorless volatile liquid It is mainly used as a standard for the determination of octane number. It can also be used for the preparation of anesthetics, solvents, raw materials for organic synthesis and experimental reagents Store in a cool and ventilated warehouse Keep away from fire and heat source The storage temperature should not exceed 30 ℃ Keep the container sealed.
1) Heptane: content > 98%, UN No: 1206, with colorless, tasteless and non-toxic environmental protection characteristics. Product application: This product is mainly used for pesticide intermediates, pharmaceutical intermediates, fine chemicals, etc. it can replace toluene and improve the purity of intermediate products.
2) n-Heptane: used in chemical reagents.
3) Industrial grade n-Heptane: content > 98%, CN No: 32006, with colorless, tasteless and non-toxic environmental protection characteristics. Product application: This product is mainly used for pesticide intermediates, pharmaceutical intermediates, fine chemicals, etc. it can replace toluene and improve the purity of intermediate products.
4) Special heptane for PVC: content > 98%, used for thermal converter in chlor alkali industry (Applied Industries by: Inner Mongolia Yili Chemical Industry Co., Ltd., Inner Mongolia Haiji Chlor Alkali Chemical Co., Ltd., Henan Pingmei chlor alkali Co., Ltd. and Shandong Binzhou Marine Chemical Co., Ltd.).
n-Heptane is a typical nonpolar solvent. It is often used as a standard for determining octane number, anesthetic, organic synthetic raw material, etc. it is also widely used in medicine, pesticide, rubber synthesis, chemical fiber synthesis, reagent, electronic cleaning and other industries.
Heptane
Molecular formula: C7H16
Molecular weight: 100.21
CAS No.: 142-82-5
Property: colorless liquid. The melting point is – 90.7 ℃, the boiling point is 98.4 ℃, the relative density is 0.684 (20 / 4 ℃), and the refractive index is 1.3855 (25 ℃). Flash point – 1 ℃. Soluble in ethanol, chloroform, ether and benzene, insoluble in water.
Preparation method: the content of n-heptane in the fraction of platinum reforming raffinate (93-102 ℃) is more than 57%. The n-alkanes in the base are adsorbed by 5A molecular sieve in gas phase, and then desorbed by steam to obtain n-alkanes. After nickel catalyzed hydrogenation, a small amount of normal olefins are saturated and transformed into normal alkanes, and the iodine value is reduced to less than 0.1g iodine / 100g. Finally, standard n-heptane with purity of 99.9% was obtained by distillation. Industrial grade n-heptane can also be purified by concentrated sulfuric acid washing and methanol azeotropic distillation.
Widely used in the production of paints, dyes, pigments, ink, adhesives, pharmaceuticals, pesticides, food additives, feed additives, flavors and fragrances, cosmetics.
It is used in the synthesis of pharmaceutical intermediates and as a solvent in other industries.
Main Applications of n-Heptane
Background and overview
N-heptane chemical formula C7H16. Molecular weight 100.20. There are nine isomers, of which n-heptane [CH3 (CH2) 5ch3] is the most important. Colorless flammable liquid. Density 0.6837. Melting point – 90.5 ℃. Boiling point 98.4 ℃. Almost insoluble in water, slightly soluble in alcohol, soluble in ether and chloroform. Vapor and air form an explosive mixture, with an explosion limit of 1.0 ~ 6.0% (volume). Separated from petroleum fractions. It vibrates violently when burning and exploding in the cylinder. Its octane number is set to zero. Mixtures in various proportions with * isooctane (octane number is determined as 100) are often used as a standard for determining the octane number of gasoline. Toluene can be prepared by dehydrogenation and aromatization of n-heptane, which is a common solvent. At present, n-heptane is mainly produced by distillation in industry. Because the boiling points of n-heptane and C7 fractions are very similar (e.g. n-heptane boiling point 98.43 ℃, methyl cyclohexane boiling point 100.93 ℃, and the boiling point difference is only 2.5 ℃), it is difficult to separate them by ordinary distillation; Precision distillation has the advantages of high energy consumption, high production cost, low yield, and it is difficult to obtain high-purity n-heptane (> 99%); With special distillation method, the cost is high and the process is complex.
Applications
n-Heptane is a typical nonpolar solvent. It is often used as a standard for determining octane number, anesthetic, organic synthetic raw material, etc. it is also widely used in medicine, pesticide, rubber synthesis, chemical fiber synthesis, reagent, electronic cleaning and other industries. N-octane is used as solvent and chromatographic reference material, as well as organic synthesis. With the rapid development of chemical industry, medicine, electronics and other related industries, the demand for n-heptane in China will increase year by year, especially High-Purity n-Heptane has broad market prospects.
Preparation
Method 1: purification method of organic solvent n-heptane, comprising the following steps:
a. Take the raw material n-heptane, successively add sulfuric acid solution with volume concentration of 10% and nitric acid solution with volume concentration of 40%, the volume ratio of sulfuric acid and nitric acid is 1:3, shake and stand for layering, discard the acid layer and retain the organic layer; Add activated carbon into the organic layer, stir for 1 hour, add potassium permanganate for oxidation, reflux for 1 hour, and quickly distill n-heptane. This step is used to remove unsaturated hydrocarbons from raw n-heptane.
b. The n-heptane obtained in step a is passed through the adsorbent column containing modified activated carbon at the rate of 0.5 column volume / hour to further remove the highly polarized substances and benzene ring containing substances formed in the oxidation process. The activated carbon is immersed in a nitric acid solution with a mass concentration of 30%, and the nitric acid solution is attached to the surface of the activated carbon to obtain the modified activated carbon.
b ˊ. Pass the n-heptane obtained in step B into the adsorbent column equipped with 3A molecular sieve with particle size of 20 mesh to further remove water; After adsorption, the water content of n-heptane shall be controlled to ≤ 0.01%; In this step, the molecular sieve is used to remove the water in the extracted n-heptane. If the water content is > 0.03%, the molecular sieve shall be replaced before continuing the molecular sieve adsorption treatment.
B “. Replace step B ˊ The obtained n-heptane is introduced into an adsorbent column equipped with silica gel with particle size of 100 mesh to further remove impurities such as alkanes and aromatic hydrocarbons and impurities affecting absorbance.
c. The n-heptane obtained in step B “is rectified to obtain high-purity organic solvent n-heptane with purity ≥ 99%.
Distillation can be carried out in a well-known manner. A preferred method of the invention is that the heating temperature of the distillation kettle is 105 ℃, the n-heptane liquid temperature in the kettle is 103 ℃, the liquid outlet temperature is 99 ℃, and the reflux ratio is controlled to 12:1. After the rectification liquid is tested to be qualified, it shall be bottled and filled with nitrogen for storage.
Method 2: a preparation method of chromatographic grade n-heptane, the steps are as follows:
(1) Lift the raw material n-heptane with purity of about 98% above the silica gel adsorption column. The specification of the adsorption column is: the length is 1.5m, the inner diameter is 3.2cm, and the amount of silica gel is 4 / 5 of the column length. Flow into the column by gravity, control the flow rate of 50ml ~ 80ml / min, make the organic solvent fully contact with silica gel, adsorb alkane and aromatic hydrocarbon impurities therein, and remove the initial effluent (about 200 ~ 500ml), The impurities in the silica gel will be brought out at the beginning, and the effluent will be tested.
(2) The qualified n-heptane effluent flows into the diatomite adsorption column, which is the same as the silica gel adsorption column. The diatomite adsorption column can adsorb carbonyl compounds and other impurities and separate them by contacting with organic solvents. The flow rate is 50ml ~ 80ml / min, and the effluent detection absorbance is close to the index. The applicant has conducted several tests on the adsorption column (silica gel and diatomite) used in the above two steps. The results show that the combined use of the two adsorbents is better. After adsorption by two-stage adsorption column, the content of n-heptane is ≥ 99%.
(3) The n-heptane outlet liquid in step (2) is dried through the drying column. The desiccant in the drying column is anhydrous calcium chloride or calcium hydride. The water content of the dried outlet liquid is 0.01% ~ 0.05%. If it is greater than 0.05%, it is considered that the desiccant is saturated with water. Replace the desiccant before drying. After drying with anhydrous calcium chloride or calcium hydride, the water content reaches 0.01% ~ 0.05%.
(4) Put the dried effluent into the reactor for rectification, and use electric heating to control the heating temperature of 140 ℃ ~ 200 ℃, the temperature of n-heptane liquid in the reactor is 100 ℃ ~ 110 ℃, and the effluent temperature is 98 ℃ ~ 99 ℃; The reflux ratio was 10 ∶ 5 ~ 8, and the reflux ratio was gradually adjusted to 10 ∶ 12 ~ 15. Finally, the chromatographic grade n-heptane product was obtained; The distillation was carried out according to the determined process conditions, the distillation temperature and reflux ratio were controlled, and all the prepared n-heptane met the chromatographic index requirements after removing the front fraction.
(5) 0.45 for qualified finished products μ M microporous membrane filtration, bottling and storage under nitrogen protection.
Effect detection: the absorbance of the prepared chromatographic grade n-heptane finished product meets the index requirements in Table 1 within the range of 197nm ~ 400nm UV wavelength (1cm quartz absorption cell, water as reference), the content is greater than 99.0%, the moisture is ≤ 0.01%, the recovery is greater than 95%, the yield is more than 95%, and other indexes meet the requirements.
Main references
[1] Chemical Dictionary
[2] Cn201810889998.3 pressure swing adsorption extraction of n-heptane and CO production of n-octane
[3] Cn201410209265.2 purification method of high purity organic solvent n-heptane
[4] Cn201510902614.3 preparation method of chromatographic grade n-heptane
