CN100482642C

CN100482642C - Preparing process for biurea

Info

Publication number: CN100482642C
Application number: CNB200610169177XA
Authority: CN
Inventors: 曹润生
Original assignee: Juhua Group Technology Centre; Juhua Group Corp
Current assignee: Juhua Group Technology Centre; Juhua Group Corp
Priority date: 2006-12-21
Filing date: 2006-12-21
Publication date: 2009-04-29
Anticipated expiration: 2026-12-21
Also published as: CN1986524A

Abstract

The present invention is a kind of practical, economic and environment friendly biurea preparing process. Biurea is prepared with no-salt hydrazine hydrate and urea as main material and sulfuric acid as medium, and through adding catalyst, adding crystal seed and condensation reaction in heating and reflux conditions. The process has high biurea yield, high product purity, relatively low cost, short reaction period and other advantages.

Description

A kind of preparation method of hydrazo-dicarbonamide

Technical field

The present invention relates to a kind of method for preparing hydrazo-dicarbonamide, the method for preparing hydrazo-dicarbonamide of especially a kind of practicality, economy and environmental protection.

Background technology

Hydrazo-dicarbonamide, English name biarea chemical name is the hydrazo diformamide, molecular formula is C ₂H ₆N ₄O ₂. chemical formula is H ₂NCOHNNHCONH ₃, the important intermediate of the chemical foaming agent Cellmic C 121 of extensive use is arranged, the back-fire relief of the anti-skidding senior cable of also available and airstrip is anti-molten etc.

In the prior art be with have salt hydrazine hydrate and urea be raw material condensation under sulfuric acid, hydrochloric acid medium produce hydrazo-dicarbonamide.Main reaction formula in its preparation process:

1, condensation reaction

NH ₄·H ₂SO ₄+2NH ₂CONH ₂→H ₂NCOHNNHCONH ₃+(NH ₄) ₂SO ₄

2, neutralization reaction

N _H4·H ₂O+H ₂SO ₄→N ₂H ₄·H ₂SO ₄+H ₂O

H ₂SO ₄+Na ₂CO ₃→Na ₂SO ₄+H ₂O+CO ₂↑

There are the following problems for above-mentioned preparation method: 1. hydrazo-dicarbonamide is not high generally at 80-85% to the yield of hydrazine hydrate, and 2. condensation 3. existed and emits a pot phenomenon for up to 8-12 hour, the operation site acid mist is boundless and indistinct, processing safety, the relatively poor and material loss of industrial hygiene, the 4. by-product (NH of Chan Shenging ₄) ₂SO ₄Waste liquid is to contain a large amount of NaCl and Na ₂SO ₄, the processing cost height does not consequently have utility value.There is the environmental issue of generation in this preparation method.U.S. Pat 3.227,753 proposes to remove carbonate in the hydrazine hydrate in advance, though alleviated the environmental protection treatment expense, condensation was for up to 48-72 hour, and the production cycle is oversize.Therefore the problems referred to above become the difficult problem that processing is produced in puzzlement always.

Summary of the invention

The present invention be directed to the deficiency that exists in the above-mentioned background technology process for preparing biurea of a kind of practicality, economy and environmental protection is provided.Its concrete solution comprises the steps:

1 adds quantitative hydrazine hydrate and urea in the polymerization reaction kettle that has heating, stirs and can control reflux;

2 at room temperature stir condensation reaction solution, regulate pH value at 4-6 with 98% sulfuric acid;

3 by 80-134 ℃ of control reflux control setting-up point;

4 add catalyzer, regulate pH value at 2-6 with 98% industrial sulphuric acid;

An amount of crystal seed of 5 disposable addings, crystal seed are with salt-free hydrazine hydrate and the urea hydrazo-dicarbonamide that condensation forms under sulfuric acid medium;

6 filter the condensation Generation Liquid, and washing and drying gets hydrazo-dicarbonamide;

7 with condensed mother liquor and washing water merging ammonium sulfate solids.

The present invention adds crystal seed by adding catalyzer in condensation reaction, the control reflux is come control reaction temperature, produces effect preferably.The purity of hydrazo-dicarbonamide is 98%, and fusing point is 254 ℃ ± 2 ℃, and yield is at 96.0% (in hydrazine hydrate).Condensation reaction time is at 6-8 hour, even more ideal is in the hydrazo-dicarbonamide that generates impurity seldom, the hydrazo-dicarbonamide after the filtration only needs the less water washing just can get the fine hydrazo-dicarbonamide.The solid sulphuric acid amine content that evaporate to dryness obtained after mother liquor and washing water merged has reached GB535-1995 agricultural salable product index more than 20%, has utility value, has realized the ammonia nitrogen waste water zero release.

The mass ratio of salt-free hydrazine hydrate of the present invention and urea is 1: 2.5-4.0.

The salt-free hydrazine hydrate of raw material of the present invention can be the salt-free hydrazine hydrate of high density, or with the salt-free hydrazine hydrate of lower concentration, salt-free hydrazine hydrate specification of quality is specially: sodium content＜50mg/L, cl content＜50mg/L.Adopt these two kinds of selections all can obtain purity at the hydrazo-dicarbonamide of the fusing point more than 98% at 254 ℃ ± 2 ℃.

U.S. Pat 3,227,753 propose to remove carbonate in the hydrazine hydrate in advance, but prolong greatly with the urea condensation time, add and reach 24-48 hour even 72 hours.And the present invention adds the reflux of crystal seed control by adding catalyzer, has realized the preparation method shorter than the time of present acid condensation, only needs 6-8 hour.

It is considered herein that to add catalyzer very important, the catalyst-free reaction under acidic medium of salt-free hydrazine hydrate and urea is very slow, and the catalyzer that is adopted is an acids, as formic acid, acetate, oxalic acid, citric acid, phosphoric acid or and salt.Crystal seed that the present invention adds is with salt-free hydrazine hydrate and the urea hydrazo-dicarbonamide that condensation forms under sulfuric acid medium.

The present invention is because the salt-free hydrazine hydrate sodium＜50mg/L that adopts, sodium salt and impurity seldom, gained hydrazo-dicarbonamide solid purity is higher, easier washing, thereby only need to wash 1 time with less water just can obtain 98% hydrazo-dicarbonamide.

The present invention adds crystal seed (salt-free hydrazine hydrate and the urea hydrazo-dicarbonamide that condensation forms under sulfuric acid medium) by adding catalyzer, controls reflux well, not only makes reaction fast, and steadily, has eliminated emit pot and the boundless and indistinct phenomenon generation of acid mist of the prior art.

It is considered herein that condensation temp is equally very important, the height of temperature has directly determined the quality of resultant of reaction.

Embodiment

Following embodiment is used for that the present invention will be described, is not construed as limiting the invention.

Embodiment 1:

Salt-free hydrazine hydrate 500ml (is contained hydrazine hydrate 88.63 gram/L, sodium content 6.2mg/L, cl content 23mg/L) and urea 153 gram (hydrazine urine than be 1: 3.45) placed heating, electronic stirring, in 1000 milliliters of four-hole boiling flasks of thermometer and reflux, at room temperature stirring dissolves urea fully, drip sulfuric acid, regulating the pH value is 6, the reacting by heating thing, by the reflux control reaction temperature at 100 ℃-120 ℃, add catalyzer propionic acid 2.2 grams, under agitation be added dropwise to sulfuric acid, control pH to 5 adds crystal seed 0.1 gram, constantly adjust sulfuric acid dripping quantity and rate of addition, be used to keep pH value of solution value and temperature of reaction, successive reaction 6.5 hours is to reaction end, and (product of hydrazine content in the ie in solution＜0.1g/L) after filtration, washing, oven dry.

Obtain purity 98.3%, hydrazo-dicarbonamide 103.5 grams that fusing point is 252.8 ℃-254.2 ℃, the yield of hydrazo-dicarbonamide is 99.0 (in hydrazine hydrates).

Embodiment 2

Salt-free hydrazine hydrate 600ml (is contained hydrazine hydrate 123.1 gram/L, sodium content 7.6mg/L, cl content 36mg/L) and urea 254.6 gram (hydrazine urine than be 1: 3.75) placed heating, electronic stirring, in 2000 milliliters of four-hole boiling flasks of thermometer and reflux, at room temperature stirring dissolves urea fully, dropwise add sulfuric acid and transfer pH to 6, the reacting by heating thing, by the reflux control reaction temperature at 110-130 ℃, add catalyzer oxalic acid 1.5 grams, under agitation drip sulfuric acid control pH to 5, add crystal seed 0.15 gram, constantly adjust sulfuric acid dripping quantity and rate of addition, be used to keep pH value of solution value and temperature of reaction, (product of hydrazine content in the ie in solution＜0.1g/L) after filtration to reaction end for successive reaction 6.2 hours, washing, oven dry.

Obtain hydrazo-dicarbonamide 142.4 grams of 251.2 ℃-254.4 ℃ of purity 97.1% fusing points, yield is 97.4% (in hydrazine hydrate)

Embodiment 3

Salt-free hydrazine hydrate 500ml (is contained hydrazine hydrate 68.7 gram/L, sodium content 10.2mg/L, cl content 23mg/L) adding places the identical flask of embodiment 1 with urea 118.7 gram (hydrazine urine than be 1: 3.45), at room temperature stir and make it to dissolve fully, dropwise add sulfuric acid and transfer pH to 6, the reacting by heating thing, by the reflux control reaction temperature at 90 ℃～110 ℃, add catalyzer phosphoric acid 3.3 grams, under agitation drip sulfuric acid control pH to 4, add crystal seed 0.3 gram, constantly adjust sour dripping quantity and rate of addition, be used to keep pH value of solution value and temperature of reaction, (product of hydrazine content in the ie in solution＜0.1g/L) after filtration to reaction end for successive reaction 7.8 hours, washing, oven dry.

Obtain hydrazo-dicarbonamide 78.9 grams of 251.7 ℃～254.5 ℃ of purity 97.5% fusing points, hydrazo-dicarbonamide yield (in hydrazine hydrate) is 97.3%.

Embodiment 4

Salt-free hydrazine hydrate 600ml (is contained hydrazine hydrate 62.8 gram/L, sodium content 41.3mg/L, cl content 36mg/L) adding places the identical flask of embodiment 2 with urea 140.4 gram (hydrazine urine than be 1: 3.75), at room temperature stir and make it to dissolve fully, dropwise add sulfuric acid and transfer pH to 6, the reacting by heating thing, by the reflux control reaction temperature at 110 ℃～130 ℃, add catalyzer phosphoric acid and oxalic acid mixing acid 3.8 grams, under agitation drip sulfuric acid control pH to 5; Disposable adding crystal seed 0.07 gram is constantly adjusted dripping quantity and rate of addition, is used to keep pH value of solution value and temperature of reaction, successive reaction 6.0 hours to reaction end (product of hydrazine content in the ie in solution＜0.1g/L) after filtration, washing, oven dry.

Obtain hydrazo-dicarbonamide 86.2 grams of 252.3 ℃～254.5 ℃ of purity 98.4% fusing points, hydrazo-dicarbonamide yield (in hydrazine hydrate) is 97.5%.

Claims

1. a process for preparing biurea is characterized in that comprising the steps:

1.1 in the condensation reaction still that has heating, stirs and can control reflux, add salt-free hydrazine hydrate and urea;

1.2 at room temperature stirring reaction liquid is regulated the pH value at 4-6 with 98% industrial sulphuric acid;

1.3 by the reflux control reaction temperature;

Catalyzer is made in the back adds formic acid, acetate, propionic acid, oxalic acid, citric acid, phosphoric acid 1.4 heat up one or both and above mixing, continues to carry out condensation reaction with 98% industrial sulphuric acid adjusting pH value at 4-6;

1.5 disposable adding is with salt-free hydrazine hydrate and the urea hydrazo-dicarbonamide that condensation forms under sulfuric acid medium;

1.6 the condensation resultant is filtered, washs, dries, obtain the hydrazo-dicarbonamide product.

2. process for preparing biurea according to claim 1, the mass ratio that it is characterized in that salt-free hydrazine hydrate and urea are 1: 2.5～4.