Method for producing n-hexanol

(1) is generally prepared by catalytic hydrogenation and reduction of caproic acid in industry. In large-scale industrial production, ethylene was used as raw material to synthesize trihexyl aluminum in the presence of triethyl aluminum catalyst, and then trihexyl aluminum was oxidized to obtain trihexyl aluminum, which was hydrolyzed to n-hexanol. This is the famous Ziegler method, which is used to synthesize primary alcohols with uniform carbon number. The three-step reaction equation is as follows:

Synthesis of triethylaluminum: 2Al +3H2+6C2H4→ 2Al(C2H5)3.

Chain extension reaction: Al (C2H5) 3+6C2H4→ [C2H5 (C2H4) 2] 3al.

Oxidation: 2 [C2H5 (C2H4) 2] 3al+3o2 → 2 [C2H5 (C2H4) 2O] 3al.

Hydrolysis: 2 [C2H5 (C2H4) 2O] 3al+3H2O → 6C2H5 (C2H4) 2OH+Al2O3.

It can also be produced by oxidation of n-hexane, but the product is often a mixture of different isomers of hexanol, and n-hexanol can be obtained by distillation separation.

Hexanol often contains other alcohols, which is difficult to separate. The better purification method is esterification with p-hydroxybenzoic acid, ester recrystallization, saponification, separation of water layer, drying with potassium carbonate or calcium sulfate, distillation and interception of n-hexanol fraction.

(2) Ethyl hexanoate is reduced by sodium metal in absolute ethanol to obtain n-hexanol and ethanol, and pure n-hexanol is obtained through rectification and separation.

(3) Butyl magnesium bromide can be obtained by the reaction of bromobutane with magnesium chips, and then reacted with ethylene oxide to obtain hexanol. In the presence of catalyst iodine, anhydrous ether solution of bromobutane reacts with magnesium chips under stirring. During the reaction, reflux and waterless must be realized. The dropping speed of bromobutane anhydrous ether should be controlled to make the reaction liquid boil continuously. After the dropwise addition, ethylene oxide should be introduced, and the feeding speed should be controlled in the cooling state to keep the reaction temperature at 65438 00℃. After the introduction, the cooling was stopped, so that the temperature of the reaction system increased slightly, resulting in a slight boiling. After boiling, the reactants are heated in a water bath. When half of the total amount of ether is distilled off, appropriate amount of dry benzene is added, stirred and distilled until the steam temperature reaches 65℃, and then the mixture is completely refluxed to be viscous. After cooling, add an appropriate amount of ice water for hydrolysis, and add 30% sulfuric acid while cooling until the precipitated magnesium hydroxide is completely dissolved. Then steam distillation, adding 20% sodium hydroxide into the water layer from which the distillate is separated, heating in a steam bath, stirring for 1-2h, then steam distillation, distilling the obtained oil layer, and distilling the collected fraction at 85- 154+057.

Industrial chain

Reference Mass The reference mass of n-hexanol used for plasticizer production is as follows:

Alcohol content% ≥98.9

Hydroxyl value mgKOH/g 543

Acid value mgKOH/g (calculated by acetic acid) < 0.00 1

Carbonyl value mg KOH/ g 0.05

Relative density (20/20) 0.820

Boiling point℃ 15 1~ 157

Chromaticity (apha)