JPS5953457A - Stabilization of methacrylonitrile - Google Patents

Abstract

PURPOSE:To keep methacrylonitrile at a high temperature stably for a long period with extremely small amount of additive, by adding pyrogallol in combination with hydroquinone to the process liquid, etc. of the purification process. CONSTITUTION:Pyrogallol and hydroquinone are added to the process liquid of the purification process for distilling the ammoxidation reaction product composed mainly of methacrylonitrile to obtain the product methacrylonitrile, or added to the product methacrylonitrile. The amounts of pyrogallol and hydroquinone are preferably 20-50ppm and 100-200ppm, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention describes the stability ratio method for methacrylonilyl (hereinafter abbreviated as MAN). Or MAN when storing product MAN
Regarding the stabilization method.

M A N is produced by a gas phase catalytic reaction, that is, an ammoxidation reaction, with isobutylene or tertiary butyl ammonia and oxygen. This reaction product is mainly composed of M A N and contains acetonitrile, methacrolein, η acid, acrylonitrile, isobutyronitrile, and the like. In order to obtain a highly pure product M A N from a reaction product containing these by-products, the conventional method is to absorb the reaction product using water as a solvent, recover it by extractive distillation using water as a solvent, and collect the recovered liquid. De-bamboo acid j, dehydration O1;, low fraction^1 in the column, distillation in the product column 1;
I got N.

However, since it is an unsaturated nitrile compound with polymerizable properties, it polymerizes during the heating distillation purification process or during storage to form a 10 polymer, resulting in a low product yield. , ■1 There is a possibility that the heat generated during the reaction will significantly accelerate the y1R1 reaction. For this reason, it was necessary to stabilize the process liquid or to prevent polymerization of MAN during storage.

This invention was made in view of the above circumstances, and its purpose is to propose a method for stabilizing MAN that prevents polymerization for a long period of time even at high temperatures by adding a highly dependent cross-agent. . The gist of B is that one ammoxidation reaction containing MAN as the main component is distilled and the product M A
This is a method for stabilizing MAN, which is characterized by adding pyrogallol and hydroquinone to the process liquid of the purification process for obtaining N, to the raw product MAN.

Hydroquinone has traditionally been used as a stabilizer for polymerizable monomers, but with the addition of hydroquinone, it is possible to stably print a high M A N of 14 degrees over a long period of time. However, it was difficult to add a large amount of lubricant and was not practical. However, the addition of hydroquino/pyrrol) (may be a mutual effect?
It became possible to keep Takanishiki's ttIA N-4 low for a long time until the end of the first three years.

The amount of hydroquinone/pyrogallol added varies depending on the temperature of the target process liquid or product MAN, the required stabilization time, etc., but is usually 50-400 wtpl+m.

Preference 1. < i, i, l 1) (1, 21) +I
WLljllrrl, pyrogallol is 10-2 (1
+l wtpl++n, preferably 20-50wLpp
It is a giant IX.

Example-1 The following test solution containing MAN, a small amount of methacrolein, acrylonitrile, and hydrocyanic acid was added with pyrogallol and hydroquinone at a predetermined concentration.
The sample was sealed in a pressure-resistant transparent ampoule at 20 m2 under nitrogen gas, and stored at 1()0°C in a light-shielded state. The time when cloudiness or precipitate was observed in the sample was defined as the polymerization initiation time. The results are shown in Table 1.

Table 1 Pyrogallol, hydroquinone addition M and polymerization initiation time Test solution composition MAN 94.6, methacrolein 2.98' Acrylonitrile 1.18' Hydrocyanic acid 0.93' Water 0.319. .

Example 2 Pyrogallol and hydroquinone were added to a test liquid with a composition mainly consisting of the three components MAN, methacrolein, and acrylonitrile, with a predetermined concentration of pyrogallol and hydroquinone. Table 2 shows the results of the first test conducted on the same row F as in the test row-1.

Table 2 Addition of pyrogallol and hydroquinone and polymerization start time test solution composition MAN 35.4 9
f.

Methacrolein aa, 696 Acrylonitrile 28.8 Acetone 2.3

Claims (1)

[Claims] (1) Adding pyrogallol and hydroquinone to the process liquid or product methacrylonitrile of the purification process in which the ammoxide reaction product containing methacrylonitrile as a main component is distilled to obtain the product methacrylonitrile. Characteristic method for stabilizing methacrylonitrile.