Preparation or source of p-toluene

Can be separated from phenol oil or tar acid, can also be used to p-toluidine diazotization, hydrolysis and obtained. The main synthetic methods are: alkali fusion of p-toluene aromatic sulfonate, hydrolysis of p-toluene halogenated aromatic hydrocarbons, electrophilic substitution on the aromatic ring of phenolic compounds, and oxidation of p-toluene isopropylbenzene.

Traditional synthesis methods are mainly used in the synthesis method, but also coking, oil shale dry distillation and city gas by-products of mixed cresols in the separation of to. Between, p-cresol can be separated by *** boiling method, urea method, dissociated benzene extraction method, sulfonation hydrolysis method. The main synthetic methods are isopropyltoluene method, o-xylene oxidation method, phenol alkylation method, chloromethyl hydrolysis method and toluene sulfonation alkaline melting method, etc. Commonly used methods are isopropyltoluene method, toluene sulfonation alkaline melting method and o-xylene oxidation method.

Specific preparation process: in the iron reaction pot, add 1kg of sodium hydroxide, potassium hydroxide 400g, heated to 230 ° C, stirring vigorously, add sodium p-toluene sulfonate 600g in batches. each batch, to be gradually increased reaction temperature, the reactants become dilute, and then add the next batch, about 30 minutes to add the end. Finally, the temperature was raised to 300°C. The reactants were refoamed and the foam rose with vigorous stirring. When the temperature rises to about 330°C, the foam disappears, the reactants darken and hydrogen gas is produced from them. The reactants were poured into an iron pan and cured when cold.

The solid is dissolved in 7 liters of water and neutralized with 880 ml of concentrated sulfuric acid prepared with 2 liters of water in dilute sulfuric acid; the reaction is exothermic until it boils, and the acidification is carried out to the point that there is a distinctive odor of sulfur dioxide, and then a water distillation is carried out. To distillate to bromine water only little precipitation, stop distillation. The distillate is saturated with sodium chloride and separated into oil. The aqueous layer is then subjected to hydrodistillation. The oily material was distilled under reduced pressure and the fraction at 95-96°C/2.0 KPa was collected to give 220 g of p-methylphenol in about 70% yield.