How do phenols and halobenzene become benzene? How to tell the difference between phenol and benzene

The classic method is to sulfonize benzene and then melt it with caustic soda, which was first established by Monsanto in 1923.

Traditional methods of development. Because of concentrated sulfuric acid and sodium hydroxide.

Both are very common and readily available reagents, so this route is preferred for preparing phenol in small quantities without large equipment. The disadvantage is also obvious, that is, the consumption of mixed acid and caustic soda is very large and the cost is very high. From the point of view of today's processes, it is outdated for large-scale industrial production.

Now the most classic method in the industry is cumene oxidation. To put it simply, benzene and propylene are prepared by Friedel-Crafts alkylation reaction induced by phosphoric acid, and then cumene is oxidized to cumene hydrogen peroxide, and finally cumene hydrogen peroxide is hydrolyzed-rearranged under acidic conditions to generate phenol and acetone.

The biggest advantage of cumene is the atom economy, i.e. all the substrates of the reaction are used to make the product – phenol and acetone are very important basic chemical raw materials. At the same time, benzene and propylene, the primary raw materials of cumene oxidation, are the basic products of petrochemical industry, which are cheap and easy to obtainCumpene oxidation:

Cumene is oxidized with air to produce peroxide.

in dilute sulfuric acid. In the presence of peroxides, the peroxide decomposes to form phenol and acetone C6H5-CH(CH3)2-O2-->C6H5-C(CH3)2-OOH--H--C6H5OH CH3CoCH3

Sulfonation alkali melting method: sulfonation of benzene to generate benzene sulfonic acid with concentrated sulfuric acid sulfonating agent.

Benesulfonic acid is neutralized with sodium hydroxide to obtain sodium benzenesulfonate, which is eutectic with sodium hydroxide to obtain sodium phenol. Sodium phenol is acidified to obtain phenol.

Cumpene method: propylene with benzene in aluminum chloride.

catalyze, at 80-90 degrees Celsius.

An alkylation reaction is carried out to obtain cumene. Cumene is oxidized with air at a pressure of 100-120 degrees Celsius and 300-400 kPa to produce cumene hydrogen peroxide. Cumene hydrogen peroxide is cracked into acetone and phenol by atmospheric pressure at 60 °C with sulfuric acid.

Chlorobenzene hydrolysis: benzene and chlorine.

Under the catalysis of iron, chlorine is obtained by chlorination. The aqueous solution of chlorobenzene and sodium hydroxide is catalytically hydrolyzed under high temperature and high pressure to generate sodium phenol, which is acidified to obtain phenol. The chlorine of chlorobenzene is very inactive and needs to be catalyzed at high temperature and high pressure and catalyzed by a catalyst to be successfully hydrolyzed.

Halogenyl phenol.

In an autoclave with concentrated heat sodium hydroxide.

Hydrolysis, plus acid halobenzene aniline: reacts with ammonia catalyzed by ATM and Cu2O aniline halobenzene: with nitrous acid at low temperatures.

Diazotization, addition of the corresponding halide (except f), raised to room temperature. The introduction of fluorine can be obtained by heating and decomposing diazo salt by adding tetrafluoroborate to crystallize diazonium salt tetrafluoroborate (except for diazonium tetrafluoroborate salt, the rest of the diazo salts are easy to be solid **) aniline Phenol: After making diazonium salt, heat it in aqueous solution Phenol aniline:

It is first nitrified to 2,4-dinitrophenol, reduced to 2,4-diaminophenol with iron powder + hydrochloric acid, and then halogenated and hydrolyzed to make halogen.

It becomes a hydroxyl group. Diazotization, reduction with hypophosphorous acid. It reacts with ammonia to form triphenylamine.

It is then diazotized to reduce benzene. Then nitrified with mixed acid, and then reduced with iron powder + hydrochloric acid to obtain aniline. Phenol Halobenzene:

First make aniline, and then make <> according to the method of aniline halobenzene

Phenol reacts in activated zinc powder or zinc amalgam to form benzohalobenzene is generally reductive dehalogenation into benzene in one step, such as bromobenzene and lialh4 reaction to generate benzene and hydrogen bromide.

Toluene can be prepared by air oxidation reaction by the specific steps are as follows:

Toluene is added to the reactor, and catalysts such as CuCl2, MNO2, etc. are added.

Toluene is heated to about 100-110, oxygen is introduced, and the reaction proceeds.

After the reaction is completed, the reaction mixture is cooled to room temperature and added to dilute acids, such as dilute hydrochloric acid, dilute sulfuric acid, etc., to neutralize it.

The mixture is then separated by distillation and other methods to obtain a phenol product.

The reaction equation is as follows:

C6H5CH3 + C6H5OH + H2O It should be noted that when the air oxidation reaction is carried out, the reaction temperature and oxygen influx rate should be controlled to avoid the impurity of the product and the occurrence of side reactions. In addition, safety measures need to be taken during the reaction, such as preventing oxygen leakage.

1. Functional groups reacting with sodium: carboxyl group, phenolic hydroxyl group, alcohol hydroxyl group.

2. Functional groups reacting with sodium hydroxide: carboxyl group, phenolic hydroxyl group.

3. Functional group reacting with sodium bicarbonate: carboxyl group.

Phenol contains phenolic hydroxyl groups, which can react with sodium and sodium hydroxide, but not with sodium bicarbonate.

The phenol solution can be washed with alcohol when it is stained with **. A small fraction of phenol is exposed to air and is oxidized by oxygen to quinone and has a pink color. When ferric ions turn purple, this method is usually used to test phenol.

FeCl3 was added separately, and the blue-purple Fe(C6H5O)6]3- precipitate was phenol. Benzene, toluene has no phenomenon, and then add purple acidic KMNO4 solution such as coarse, and the purple color of the solution fades to toluene. Toluene is oxidized to benzoic acid, potassium permanganate is reduced to colorless Mn2+, and benzene remains unchanged in color.

Reagent: acidic potassium permanganate solution.

Principle: Toluene is the one that can fade the acidic potassium permanganate, otherwise it is benzene.

Explanation: If there is h on the carbon on the benzene ring branched chain (the carbon connected to the benzene ring), then the branched chain can be oxidized to a carboxyl group (-Cooh) by the acid potassium permanganate, such as toluene can be oxidized by the acid potassium permanganate to benzoic acid. Benzene does not react with acidic potassium permanganate.

This method of hydrolysis of bromobenzine seems to be direct, but in fact it is not easy to react, so it should be nitrified with concentrated H2SO4 and HNO3 and then reduced to aniline by SN and HCL, then nitrous acid to become diazo salt, and finally diazonium salt hydrolyzed with water to release N2.

Benzene is first substituted, for example, when iron is used as a catalyst and reacts with bromine to form monobromobenzene. After hydrolysis of monobromobenzene in a strong alkali, phenolate salt can be generated, and then crystallized in an acidic solution.

Chlorobenzene can be synthesized from benzene, and then phenol can be obtained by hydrolysis of chlorobenzene.

c6h6+cl2-fe→c6h5-cl+hcl

C6H5-Cl+H2O- catalyst, pressurized, heated C6H5-OH+HCl