JPS60260541A - Method for stabilizing hydroxylamine - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful for various chemical reactions, etc., by using and adding stannic acid to hydroxylamines unstable against oxidation for stabilizing them, and sufficiently controlling a reduction of yield in preparation, and capable of storing the product for a long period. CONSTITUTION:0.1-10,000ppm stannic acid such as sodium stannate is added to stabilize a hydroxylamine expressed by formula I (R<1> represents alkyl; R<2> represents H or R<1>, provided that alkyl represents <=6C lower alkyl including 1-6C cycloalkyl, lower alkenyl an their lower alkyl-substitution products and R<1> together with R<2> forms tetramethylene or pentamethylene, etc.), e.g. N,N-diethylhydroxylamine, or an aqueous solution thereof to obtain the hydroxylamine in high yield. EFFECT:The method exhibits a stabilizing effect for a long period even at a thermal decomposition temperature of amine oxide, etc. in the presence of water in the state of contamination by metal or its ion. USE:An antioxidant, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for stabilizing hydroxylamines.

Hydroxylamines, especially hydroxylamines substituted with alkyl groups, etc., have a strong reducing power and are used in various chemical reactions, and also have a wide range of uses as mization inhibitors and radical polymerization inhibitors. There is.

In particular, low-toxic substituted hydroxylamines such as N,N-diethylhydroxylamine and hydroxylpiperidine are widely used as popcorn polymerization inhibitors for olefin compounds such as butadiene and sutylene.

The present invention provides a means to stabilize these hydroxylamines, which are unstable to oxidation and prone to decomposition during production and storage.

BACKGROUND OF THE INVENTION As stabilizers for N,N-dialkylhydroxylamines, alkali metal salts of dialkyldithiocarbamates are known, as described in US Pat. No. 1,033,260. Also.

Phenols are known as stabilizers for hydroxylamine (Japanese Patent Publication No. 52-48118).

Problems to be Solved by the Invention However, hydroxylamines, especially hydroxylamines in which the nitrogen atom is substituted with an alkyl group or an alkylene group,
It has strong reducing power and is extremely easily oxidized. Furthermore, stabilizers based on ordinary antioxidant effects could not provide sufficient stabilizing effects and were prone to deterioration.

The present invention stabilizes hydroxylamines that deteriorate extremely quickly, thereby making it possible to produce hydroxylamines in good yield even in thermal decomposition methods using high temperatures, and making it possible to store products for a long period of time. The present invention provides a stabilization method for Prevention of side reactions such as oxidation prevents dangers due to the possibility of sequential abnormal reactions,
It is also important to ensure safety.

As a conventional method for producing hydroxylamines.

Methods such as oxidation of amines, thermal decomposition of tertiary amine oxide, and hydrogenation of aldoximes are known, but since the generated hydroxylamines are easily oxidized, it is generally necessary to quickly remove the products from the system. Some effort is needed. Especially in pyrolysis methods.

Deterioration due to heat is significant, and oxidation methods usually result in further oxidation and a decrease in yield. However, there are limits to the method of taking it out of the system, and it was inevitable that some of it would deteriorate while it remained in the system. In addition, when transporting or storing product hydroxylamines, oxygen, light,
The use of a stabilizer is unavoidable because the deterioration caused by heat is significant, but conventional stabilizers have not had sufficiently satisfactory performance.

Means to Solve the Problem: The present inventors have fundamentally investigated measures to prevent the deterioration of these hydroxylamines, and have found that the cause of oxidation and deterioration of hydroxylamine is not simply due to oxygen in the atmosphere. When hydroxylamine is manufactured industrially, certain metals are likely to be mixed in from the equipment and present in the reaction solution or product.2 Trace amounts of metals such as iron and copper can have a large effect by promoting oxidation by oxygen. and further this,
The present invention was completed based on the discovery that the addition of stannic acid is effective in preventing the adverse effects of these metals.

The present invention is a method for stabilizing hydroxylamines, which is characterized by adding stannic acid.

Hydroxylamines The hydroxylamines targeted by the present invention are:

In the formula 0, R1 is an alkyl group and R
2 is a hydrogen atom or an alkyl group. However, in R1 or R2, the alkyl group refers to not only the original alkyl group (usually a lower alkyl group with 6 or less carbon atoms), but also a cycloalkyl group (05 to C6), a lower alkenyl group, or a lower alkyl substituted group thereof. For convenience, it also includes cases where R1 and R2 are linked to form a detramethylene group or a pentamethylene group, and lower alkyl substituted products thereof.

For example, N-methylhydroxylamine, N,'N-dimethylhydroxylamine, N-methyl-N-ethylhydroxylamine, N-ethylhydroxylamine, N,
N-diethylhydro-4-zylamine, N,N-dipropylhydroxylamine.

N, N-di-tart-butylhuman[]xylamine,
N-cyclohexylhydroxylamine, N-hydroxylpiperidine and the like are objects of the present invention.

A typical one of these is N,N-diethylhydroxylamine.

Addition of stannic acid The stabilizing agent that characterizes the present invention is stannic acid. Stannic acid is commonly used as an alkali metal salt 2, typically as sodium stannate, which is the most readily available and highly effective. Non-salt stannic acid and salts of other metals such as potassium, lithium, calcium, and magnesium can also be used as long as they do not impair the stability of the hydroxylamines.

Hydroxylamines, in liquid or solution state, are significantly stabilized by the addition of stannic acid.

The most common embodiment is to add and dissolve stannic acid into an aqueous solution containing the hydroxylamines or raw materials thereof. In addition, stannic acid may be added to hydroxylamines in various states, such as organic solvent solutions, liquids, and aqueous hydrochloride solutions. The amount of excess 2 is determined depending on the degree of treatment, processing temperature, etc., and is usually about 3 to 30 times the amount of atoms present such as iron or copper. 0. lp
Additions from pm to 100 ppm, especially from 1 to 300 ppm are commonly used. .

Effects of the Invention The addition to stannic acid according to the present invention is stable for a long time in the presence of water and in the presence of metals or their ions under the actual use conditions of hydroxylamines, such as the thermal decomposition temperature of amine oxide. It exhibits a chemical effect and sufficiently suppresses yield loss during production. Also.

Allows long-term storage of hydroxylamine products.

The present invention will be explained below based on specific examples.

Quantitative analysis of N,N-diethylhydroxylamine and diethylamine was performed at 0. Calculations were made based on an automatic titration curve prepared using IN hydrochloric acid.

Example 1 N,N-diethylhydroxylamine was produced by dropping an aqueous solution of triethylamine oxide (TEAO) into a heat medium liquid and thermally decomposing it at 120°C while distilling off the product (Japanese Patent Publication No. 1973 - Now 13056), at this time, 1.4p of Fe3+ ions were added to the raw material T' E A O.
The yield when pm was included (relative to TEAO) was 86.2%, and the yield of diethylamine produced as a by-product by decomposition of N,N-diethylhydroxylamine was 7.4%.

When sodium stannate was added (the amount added was] = 03+
As shown in Table 1 (molar ratio to ions), the yield of N,N-diethylhydroxylamine (D E HA ) was improved and the by-product of diethylamine (DEA) was reduced.

Table 1 The yield is 98.1%.

Example 2 In the same method as in Example 1, the yield of N,N-diethylhydroxylamine was 95.3% when the raw material triethylamine oxide contained 3.4 ppm of Cu2+ ions.
(DEA by-product 2.5%).

When 12.0% of sodium stannate was added (the amount added is a molar ratio to CU2+ ions), the yield of N,N-diethylhydroxylamine was 96.6% (DEA by-product 1.5%).
%).

Example 3 N containing 0.7 mmol/1 Fe3+ ion.

N-diethylhydroxylamine aqueous solution (initial concentration 20
．． 5% by weight) at 70°C for 5 days.

When N,N-diethylhydroxylthymine was quantified, it was found to have decreased to 7.5%. When 2.5 mmol/1 sodium stannate was added before heating, the concentration was 15.8%. When the amount of sodium stannate added was 5.0 mmol/1, the concentration after heating was 19.7%.

Comparative Example Tests similar to those in Example 3 were conducted on the following substances, but none were effective.

Pyrogallol, catechol, 2,3-dihydroxynaphthalene, 2,3-dihydroxybenzoic acid.

Even when 4-tert-butylchicol EDTA-2Na salt was added, most DE
DEIA disappeared in one day, and the stabilizing effect of DEIA was not observed using a conventional sequestering agent.

When 5 mmol/1 of zinc diethyldithiocarbamate is added, the N,N-diethylhydroxylamine vagueness after being kept at 70°C for 5 days is 12°3%, and even if the amount added is 10 mmol/1, the concentration of N,N-diethylhydroxylamine is 13%. Only .2% remained.

Claims (1)

[Claims] Method for stabilizing hydroxylamines characterized by adding stannic acid