Synthesis method of p-hydroxybenzonitrile

Abstract

The invention discloses a synthesis method of p-hydroxybenzonitrile. The method specifically comprises the following steps: uniformly dispersing p-hydroxybenzoic acid, urea, a dehydrating agent and adehydrating catalyst in an inert solvent with a high boiling point, then heating and reacting, filtering after a reaction to obtain filtrate, performing vacuum rectification on the filtrate and crystallizing to obtain the p-hydroxybenzonitrile. The invention can guarantee a relatively good dehydration effect, greatly reduces the using amount of the dehydrating agent at the same time, greatly reduces the generation of solid waste and improves the reaction yield.

Description

technical field

[0001] The invention relates to the technical field of organic synthesis, in particular to a synthesis method of p-hydroxybenzonitrile. Background technique

[0002] p-Hydroxybenzonitrile, also known as 4-cyanophenol or p-cyanophenol, is widely used in the synthesis of various medicines, spices, pesticides, liquid crystal materials and corrosion inhibitors. Important intermediates such as benzonitrile. In recent years, as an important fine intermediate, the demand for p-hydroxybenzonitrile has been increasing, which makes the research on its industrial synthesis process more urgent.

[0003] At present, the existing synthesis method of p-hydroxybenzonitrile needs to use a large amount of dehydrating agent, and a large amount of dehydrating agent cannot be well dispersed in the reaction system, which affects the reaction yield and produces a large amount of solid waste. Contents of the invention

[0004] In order to solve the above-mentioned technical prob...

Examples

Embodiment 1

[0015] A kind of synthetic method of p-hydroxybenzonitrile, specifically: 1mol p-hydroxybenzoic acid, 2mol urea, 0.3mol phosphorus pentoxide, 0.02mol dibutyl tin oxide, 0.2mol methyl benzoate are dropped in the reactor, Stir evenly, disperse p-hydroxybenzoic acid, urea, phosphorus pentoxide, and dibutyltin oxide evenly in methyl benzoate, then heat to 160°C, keep warm for 1 hour, and filter after the reaction to obtain the filtrate. The filtrate was subjected to rectification under reduced pressure, the temperature was controlled at 100°C, and p-hydroxybenzonitrile was obtained by crystallization with a yield of 92.1%.

Embodiment 2

[0017] A kind of synthetic method of p-hydroxybenzonitrile, specifically: 1mol p-hydroxybenzoic acid, 3mol urea, 0.5mol phosphorus pentoxide, 0.05mol dibutyl tin oxide, 0.5mol ethyl benzoate are dropped in the reactor, Evenly disperse p-hydroxybenzoic acid, urea, phosphorus pentoxide, and dibutyltin oxide in ethyl benzoate, then heat to 180°C, keep warm for 2 hours, filter after the reaction to obtain the filtrate, and reduce the filtrate Pressure rectification, temperature control at 150°C, crystallization to obtain p-hydroxybenzonitrile with a yield of 94.2%.

Embodiment 3

[0019] A kind of synthetic method of p-hydroxybenzonitrile, specifically: 1mol p-hydroxybenzoic acid, 4mol urea, 0.8mol phosphorus pentoxide, 0.1mol dibutyltin oxide, 0.7mol methyl benzoate are dropped in the reactor, Evenly disperse p-hydroxybenzoic acid, urea, phosphorus pentoxide, and dibutyltin oxide in methyl benzoate, then heat to 220°C, keep warm for 3 hours, and filter after the reaction to obtain the filtrate. Pressure rectification, temperature control at 250°C, crystallization to obtain p-hydroxybenzonitrile with a yield of 96.4%.

technical field

[0001] The invention relates to the technical field of organic synthesis, in particular to a synthesis method of p-hydroxybenzonitrile. Background technique

[0002] p-Hydroxybenzonitrile, also known as 4-cyanophenol or p-cyanophenol, is widely used in the synthesis of various medicines, spices, pesticides, liquid crystal materials and corrosion inhibitors. Important intermediates such as benzonitrile. In recent years, as an important fine intermediate, the demand for p-hydroxybenzonitrile has been increasing, which makes the research on its industrial synthesis process more urgent.

[0003] At present, the existing synthesis method of p-hydroxybenzonitrile needs to use a large amount of dehydrating agent, and a large amount of dehydrating agent cannot be well dispersed in the reaction system, which affects the reaction yield and produces a large amount of solid waste. Contents of the invention

[0004] In order to solve the above-mentioned technical prob...

Examples

Embodiment 1

[0015] A kind of synthetic method of p-hydroxybenzonitrile, specifically: 1mol p-hydroxybenzoic acid, 2mol urea, 0.3mol phosphorus pentoxide, 0.02mol dibutyl tin oxide, 0.2mol methyl benzoate are dropped in the reactor, Stir evenly, disperse p-hydroxybenzoic acid, urea, phosphorus pentoxide, and dibutyltin oxide evenly in methyl benzoate, then heat to 160°C, keep warm for 1 hour, and filter after the reaction to obtain the filtrate. The filtrate was subjected to rectification under reduced pressure, the temperature was controlled at 100°C, and p-hydroxybenzonitrile was obtained by crystallization with a yield of 92.1%.

Embodiment 2

[0017] A kind of synthetic method of p-hydroxybenzonitrile, specifically: 1mol p-hydroxybenzoic acid, 3mol urea, 0.5mol phosphorus pentoxide, 0.05mol dibutyl tin oxide, 0.5mol ethyl benzoate are dropped in the reactor, Evenly disperse p-hydroxybenzoic acid, urea, phosphorus pentoxide, and dibutyltin oxide in ethyl benzoate, then heat to 180°C, keep warm for 2 hours, filter after the reaction to obtain the filtrate, and reduce the filtrate Pressure rectification, temperature control at 150°C, crystallization to obtain p-hydroxybenzonitrile with a yield of 94.2%.

Embodiment 3

[0019] A kind of synthetic method of p-hydroxybenzonitrile, specifically: 1mol p-hydroxybenzoic acid, 4mol urea, 0.8mol phosphorus pentoxide, 0.1mol dibutyltin oxide, 0.7mol methyl benzoate are dropped in the reactor, Evenly disperse p-hydroxybenzoic acid, urea, phosphorus pentoxide, and dibutyltin oxide in methyl benzoate, then heat to 220°C, keep warm for 3 hours, and filter after the reaction to obtain the filtrate. Pressure rectification, temperature control at 250°C, crystallization to obtain p-hydroxybenzonitrile with a yield of 96.4%.