Higher fatty acids

chemical substances

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Higher fatty acids, which contain more than ten carbon atoms fatty acid 。 For example, stearic acid, palmitic acid, oleic acid, etc. Stearic acid and palmitic acid belong to saturated higher fatty acids, which are solid at room temperature. The hydrocarbon radical of oleic acid contains a double bond, which belongs to unsaturated higher fatty acid and is liquid at room temperature.

Higher fatty acids contain carboxyl groups in their molecules, so they have the properties of carboxylic acids. The main component of soap we use daily is the sodium salt of higher fatty acids. There is an unsaturated double bond in the molecule of oleic acid, which can also react with hydrogen or chlorine. For example, liquid oleic acid reacts with hydrogen under the action of metal nickel to generate solid stearic acid.^[1]

Chinese name: Higher fatty acids
Form: In the form of ester

Presence: In animal and vegetable oils
Discipline: Chemistry
Field: life sciences

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Fatty acids in nature mainly exist in animal and vegetable oils in the form of esters, and the amount of natural fatty acids is very small.^[2]

Production method - early high fatty acids were mainly extracted from animal and vegetable fats. With the development of modern petrochemical industry, high fatty acids can be produced by synthesis. In the United States and Japan, natural oils are still used as the main raw materials olefin Is the production route of raw materials; China, the Soviet Union and Eastern European countries mainly paraffin wax (See Petroleum wax ）It is produced for raw materials.

with Natural grease As raw material: the carbon number of fatty acids in oil is almost all even, and the fatty acids obtained by this method are all even carbon products. Grease is triglyceride Class compounds, which can be added with alkali saponification 、 acidification perhaps hydrolysis Fatty acid was prepared by the method of.

In industry, Colgate Emery continuous decomposition device is used to blow high-pressure steam into the decomposition tower. The reaction temperature is 250~260 ℃, the pressure is 5.0~5.5MPa, and the retention time is 2~3h Conversion rate 98%~99%, the product passes Hydrogenation except Unsaturated fatty acid , Rejuvenation Vacuum distillation The product with purity of 99.5% was obtained.

With petroleum hydrocarbon as raw material, i.e paraffin wax Oxidation method: In 1936, German Henkel Company established the first industrial unit. The law is based on Boiling range 350~420 ℃ straight chain N-alkane ——Paraffin wax as raw material potassium permanganate or manganese dioxide -In the presence of potassium sodium catalyst, paraffin is in contact with air in the reaction tower. First, it is initiated at 120~160 ℃, 0.14~0.63MPa for 1~2h, and the control temperature is 105~120 ℃, reaction time 12~20h, yield 75%~85%, product Scrubber Remove C1~C4 acid by internal water washing, and add alkali after separating catalyst saponification , and then separate at 380 ℃, 0.6~1.3 MPa Unsaponifiable matter , and finally use sulfuric acid acidification Various grades of fatty acids are separated by refining. The consumption of paraffin wax per ton of acid is about 1.75~1.85t. The reaction can be carried out in multiple groups of oxidation towers in series or in other forms Reactor Continuous in.

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C fifteen H thirty-one COOH Palmitic acid / palmitic acid (Cetane acid)

C sixteen H thirty-three COOH margaric acid （ Heptadecanoic acid ）

C seventeen H thirty-five COOH stearic acid (Octadecylic acid)

C seventeen H thirty-three COOH oleic acid（ Octadecenoic acid ）

C seventeen H thirty-one COOH linoleic acid (Eighteen carbon Dienoic acid ）

C seventeen H twenty-nine COOH linolenic acid（ Octadecatrienoic acid ）

C nineteen H thirty-nine COOH Arachidic acid （ Eicosanoic acid ）

C nineteen H twenty-nine COOH EPA（ Eicosapentaenoic acid ）

C twenty-one H forty-three COOH oleic acid（ Docosanic acid ）

C twenty-one H thirty-one COOH DHA（ Docosahexaenoic acid ）

C twenty-three H forty-seven COOH Lignin Acid（ Tetracosane acid ）

Higher fatty acids

Etc.

Production method

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The early higher fatty acids were mainly extracted from animal and vegetable fats. With the development of modern petrochemical industry, higher fatty acids can be produced by synthesis. In the United States and Japan, natural oils are still used as the main raw materials olefin Is the production route of raw materials; China, Russia and Eastern European countries mainly paraffin wax (See Petroleum wax ）It is produced for raw materials.

with Natural grease As raw material: the carbon number of fatty acids in oil is almost all even, so the fatty acids obtained by this method are all even carbon products. Grease is triglyceride Class compounds, which can be added with alkali saponification 、 acidification perhaps hydrolysis Fatty acid was prepared by the method of. The basic reaction is: Colgate Emery continuous decomposition device is used in industry to blow high-pressure steam into the decomposition tower, reaction temperature is 250~260 ℃, pressure is 5.0~5.5MPa, residence time is 2~3h, reaction Conversion rate 98%~99%, the product passes Hydrogenation Remove unsaturated fatty acids, and then Vacuum distillation The product with purity of 99.5% was obtained.

Fatty acids produced with oils are called natural fatty acids. In addition, higher fatty acids can also be obtained from rosin , extracted from wood pulp oil slick (see Agricultural, forestry and chemical products ）。 With petroleum hydrocarbon as raw material, i.e paraffin wax Oxidation method: In 1936, German Henkel Company established the first industrial unit. The method is based on straight chain with boiling range of 350~420 ℃ N-alkane ——Paraffin wax as raw material, in potassium permanganate or manganese dioxide -In the presence of potassium sodium catalyst, paraffin is in contact with air in the reaction tower. First, the reaction was initiated at 120~160 ℃, 0.14~0.63MPa for 1~2h, controlled at 105~120 ℃, and the reaction time was 12~20h. The yield was 75%~85% Scrubber Remove C1~C4 acid by internal water washing, and add alkali after separating catalyst saponification , then separate unsaponifiable matter at 380 ℃, 0.6~1.3 MPa, and finally use sulfuric acid acidification Various grades of fatty acids are separated by refining. Acid consumption per ton paraffin wax About 1.75~1.85t. The reaction can be carried out continuously in multiple groups of oxidation towers in series or other types of reactors.

with olefin As raw materials, there are mainly the following methods:

① Alkali oxidation of primary alcohol - through olefins Carbonyl synthesis Law and Ziegler Legal Primary alcohol Generated by alkali melting sodium salt , and then acidified to obtain fatty acid:

RCH two OH+NaOH─→RCOONa+2H two

2RCOONa+H two SO four ─→2RCOOH+Na two SO four

② Straight chain Alpha olefin Hydroformylation, oxidation or carboxyl Chemical method - the basic reaction formula is:

③ Ziegler intermediate oxidation and carboxylation—— ethylene Oligomerized Alkyl aluminium Direct oxidation, or with carbon dioxide After reaction to generate trialkoxy aluminum hydrolysis Acidification:

2R3Al+9O two ─→6R′COOH+3H two O+Al two O three

R3Al+3CO two ─→(RCOO)3Al

(RCOO)3Al+3H two O─→3RCOOH+Al(OH) three

④ Kohfa—— Branched chain olefin In sulfuric acid- Boron fluoride In the presence of catalyst, under the condition of 0~80 ℃, 0.1~10MPa and carbon monoxide Water reaction can generate higher fatty acids with branched chains.^[3]

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Higher fatty acids

The main use of linear chain saturated higher fatty acids is to make soap; Unsaturated higher fatty acids can be used as Paint raw materials , or Hydrogenation Made by hydrogenation Saturated fatty acid ； belt Branched chain The higher fatty acids of thermal stability And difficult saponification It is suitable for making paints and resins. The synthetic high fatty acid with wide fraction can be used fractionation Post application.

Higher fatty acids

Open up sources of raw materials and develop various Green surfactant From the perspective of development, it has important practical significance. Natural high fatty acids are renewable resources developed from green vegetable oil and other raw materials. The most important use is to produce green surfactants. In China, we should adhere to the development path of green surfactants based on resources and in line with China's national conditions and responsible for future generations, and vigorously promote green surfactants that have been used in production.^[4]

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