IL31077A

IL31077A - Process of manufacturing nitrilotriacetonitrile

Info

Publication number: IL31077A
Application number: IL31077A
Authority: IL
Original assignee: Stauffer Chemical Co
Priority date: 1967-12-18
Filing date: 1968-11-17
Publication date: 1972-02-29
Also published as: FR1596133A; SE365207B; BE725590A; CH494211A; GB1244329A; DE1815110A1; NL6817367A; IL31077A0

Description

S.TAUFPER CHEMICAL COMPANY Q: 29277 Abstract of the Invention A process of manuf cturing nitrilotriacetonitrile in a two step continuous operation wherein ammonia, formaldehyde, and hydrogen cyanide in approximately stoichiometric portions are reacted together in a first reactor to form methylene diaminotetraacetonitrile. The methylene diaminotetraacetonitrile is then continuously conveyed to a second reactor maintained at a temperature of at least above 100°G., and under pressure and contacted with additional formaldehyde and hydrogen cyanide for a period of from three to fifteen minutes to form nitrilotriacetonitrile.

Background of the Invention Nitrilotriacetonitrile (hereinafter referred to as ΝΪΝ) is an old and well known may be described as a white crystalline solid having a melting point of between 126 » 128°C., that is substantially insoluble in water. This material finds use as a reactive intermediate. **■ Prior processes for manufacturing the NTN involve the reaction of ammonia, formaldehyde, and hydrogen cyanide in the presence of a mineral acid. The ingredients were usually introduced into a reaction vessel and agitated with a stirring mechanism to bring about intimate contact of the various components. The reaction of these components is carried out at atmospheric pressure at a temperature ranging from room temperature up to 8o°C. Under these prevailing reaction continual formation of solid intermediates and products. When these components are reacted together at room temperature, the NTN is formed within three to six days. However, at the upper level of 75°C, this time can be reduced to four to five hours. When the reaction is complete, the NTN in a crystalline form, can be recovered and after washing in good yields.

Various alternatives have been proposed, one of which involves the reaction of ammonia and formaldehyde to form hexamethylenetetraamine. The hexamethylenetetraamine is then introduced into a reaction vessel and agitated with hydrogen cyanide and additional formaldehyde in the presence of a mineral acid to form NTN as the end product. Again, these reactions take place at either room temperature or up to 8o°C, resulting in a heterogeneous medium. Also, at these temperatures the formation of NTN from the reaction products takes from three to five hours, also in relatively good yields.

Another method of forming the NTN product is to react ammonium sulfate, formaldehyde and hydrogen cyanide in an aqueous acidic medium to form NTN. However, this reaction is even more sluggish than the previous method. Moreover, because of the long reaction time requirements, and because of the heterogeneous nature of the reaction, all the known methods of forming NTN are limited to batch process operations at temperatures of up to 8o°G., and at atmospheric pressure. At these temperatures and pressures, the large in-process inventories of hydrogen cyanide necessitates the use of especially designed safety equipment to maintain control of the highly exothermic reaction and volatility of the unreacted hydrogen cyanide. These precautions must be maintained because of the highly toxic nature of the material employed. This, of course, requires a large capital investment. Moreover, the time involved of up to four to five hours to produce a commercial yield of the NTN product materially increases the cost thereof. Thus, there is a need in the industry for forming the NT composition at materially reduced rates or times, yet retaining the high yield of over 80$ necessary for commercialization.

Brief Description of the Invention It has been discovered that nitrilotriacetonitrile can be manufactured in a two step operation wherein an intermediate is formed by reacting ammonia, formaldehyde, and hydrogen cyanide in the presence of a mineral acid to form methylene diaminotetraacetonitrile. This intermediate product is then admixed with additional hydrogen cyanide and formaldehyd and heated at a temperature of at least above 100°C. and under pressure for a period of from three to fifteen minutes.

Detailed Description of the Invention In the practice of the present invention, ammonia, formaldehyde and hydrogen cyanide are reacted together under aqueous acid conditions to form methylene diaminotetraaceto-nitrile. The manner in which this intermediate product is manufactured is well known as set forth in J.A.C.S. kQ , 2J k (1926) and German Patent No. 1,159,959- This intermediate product is formed in situ by heating the reactants together for Thereafter, and without isolating the intermediate product, the methylene diaminotetraacetonitrile is reacted with at least approximately stoichiometric portions of additional hydrogen cyanide and formaldehyde to give excellent yields of nitrilotriacetonitrile, in accordance with the following reaction: NCGHs CHa.CN N-CHs-N + 2HCN + CHaO → 2N (CHSCN)3 / \ (NTN) NCCH2 CH2CN The reaction conditions for converting the intermediate product, methylene diaminotetraacetonitrile to the NTN product is at a temperature of at least 100°C, and under pressure, preferably autogeneous pressure. The upper limit of temperature under the reaction conditions would be approximately 150°C. The reaction time at 115°C, is approximately five minutes but can range between three and fifteen minutes depending on the temperature employed.

In order to illustrate the merits of the present invention, the following examples are provided: EXAMPLE 1 In a 250 milliliter flask equipped with stirrer and thermometer, was added 101 grams of a 32$ formaldehyde solution (1.25 moles). To this was added 30.5 grams (0.5 moles) of a 28$ ammonia solution at 25°C. The ammonia was added at such a rate as to keep the temperature below 30° C. After the ammonia was added the reaction mixture was cooled to 5°C, where 12.5 grams (0.125 moles) of sulfuric acid in ten milliliters of water and solution, and put into a 7 milliliter glass tube. The glass tube was sealed and then heated five minutes in a 75°C, oil bath. After the heating period the methylene diaminotetraacetonitrile which was formed precipitated from solution upon cooling to room temperature. The glass tube was opened when the contents were at 0°C. At this temperature 1.55 grams of a solution which contained 21 grams, (0.25 moles) of a 37$ formaldehyde solution, Ik grams (Ο.52 moles) of liquid hydrogen cyanide and 15 grams, of water was added to the glass tube containing the methylene diaminotetraacetonitrile. The glass tube was sealed and then heated for five minutes at ll6°C. The nitrilotriacetonitrile product obtained as a precipitate was analyzed to yield an 82$ of that theoretical obtainable.

EXAMPLE 2 The procedure as outlined in Example 1 was followed in its entirety except that the methylene. diaminotetraacetonitrile was reacted with additional hydrogen cyanide and formaldehyde at a temperature of 120°C, for five minutes. The yield in this experiment was 81$.

EXAMPLE 3 The procedure as outlined in Example 1 was repeated in its entirety except the methylene diaminotetraacetonitrile was reacted with additional hydrogen cyanide and formaldehyde at 12 eC for five minutes. The yield was 8l$.

EXAMPLE k The procedure as outlined in Example 1 was repeated except that the methylene diaminotetraacetonitrile was reacted

Claims

What is claimed is:

1. A process of manufacturing nitrilotriacetonitrile comprising the steps of: (a) contacting in a liquid state at least stoichiometric aqueous portions of ammonia, formaldehyde, and hydrogen cyanide in the presence of a mineral acid in a first reaction means to form methylene diaminotetraacetonitrile; (b) conveying the said methylene diaminotetraacetonitrile to a second reaction means that is maintained at a temperature of at least 100°C, and under pressure; (c) conveying additional formaldehyde and hydrogen cyanide in at least stoichiometric aqueous portions to said second reaction means to contact said methylene diaminotetraacetonitrile which react together to form nitrilotriacetonitrile

2. The process as set forth in Claim 1, wherein the first reaction means is maintained at a temperature of between 50 and 100°C.

3. The process as set forth in Claim 1, wherein the pressure is autogeneous and maintained between 5 and 100 psig. k.

4. The process as set forth in Claim 1, wherein the residence time of the reactants within said second reaction means can range between three and fifteen minutes.

5. The process as set forth in Claim 1, wherein steps (a), (b) and (c) are carried out continuously.

6. A process of manufacturing nitrilotriacetonitrile wherein at least stoichiometric aqueous portions of ammonia, formaldehyde and hydrogen cyanide are reacted together in the presence of a mineral acid to form methylene diaminotetraaceto-nitrile; the improvement comprising reacting said methylene diaminotetraacetonitrile with additional formaldehyde and hydrogen cyanide to form nitrilotriacetonitrile.

7. The process as set forth in Claim 6, wherein said additional formaldehyde and hydrogen cyanide is at a ratio of about l to 2.

8. The process of Claim 6, wherein the reaction of methylene diaminotetraacetonitrile with formaldehyde and hydrogen cyanide is carried out at a temperature of at least