Process for preparing nitrilotriacetonitrile

Claim 3

The method of claim 1 in which the pH is maintained at a value not more than about 1.

Claim 4

The method of claim 1 in which the temperature is maintained between about 10° and about 35° C.

Claim 5

The method of claim 1 in which the pH is maintained at a value not more than about 1 and the temperature between about 10° and about 35° C.

Claim 8

The method of claim 5 in which formaldehyde is added to a liquid phase mixture of methylene-bis-iminodiacetonitrile and hydrogen cyanide.

Claim 9

The method of claim 5 in which hydrogen cyanide is added to a liquid phase mixture of methylene-bis-iminodiacetonitrile and formaldehyde.

Claim 10

The method of claim 5 in which the temperature is maintained between about 50° and about 85° C.

Claim 13

The method of claim 9 in which all the formaldehyde is added in the step in which the adduct of ammonia and formaldehyde is formed.

Claim 14

The method of claim 9 wherein the nitrilotriacetonitrile is separated from the reaction mixture and the portion of the reaction mixture separated from the nitrilotriacetonitrile is returned to the step of formation of methylene-bis-iminodiacetonitrile.

Claim 15

The method of claim 9 in which hydrogen cyanide is added to the liquid phase containing the methylene-bis-iminodiacetonitrile and then formaldehyde is added.

Claim 16

The method of claim 9 in which formaldehyde is added to the liquid phase containing the methylene-bis-iminodiacetonitrile and then liquid hydrogen cyanide is added.

Claim 17

The method of claim 9 in which all the hydrogen cyanide is added in the step in which the adduct of ammonia and formaldehyde which has been adjusted to a pH below about 2 is reacted to form methylene-bis-iminodiacetonitrile.

Claim 20

The method of claim 15 wherein the ammonia and hydrogen cyanide are added in two stages, each stage at a different temperature.

Claim 21

The method of claim 16 wherein a portion of the stoichiometrically necessary formaldehyde is not added until the second stage.

Claim 22

The method of claim 15 wherein the ammonia and hydrogen cyanide are added in a first stage at one temperture, and hydrogen cyanide by itself is added in a second stage at another temperature.

Claim 23

The method of claim 15 wherein the molar ratio of the ammonia to the formaldehyde in the adduct lies between about 1:2.5 to about 1:9.

Claim 24

The method of preparing methylene-bis-iminodiacetonitrile of claim 1 which comprises forming an aqueous liquid phase adduct of ammonia and formaldehyde, adjusting the pH of said liquid phase between about 0 and about 2 by the addition of a strong mineral acid, adding hydrogen cyanide to said liquid phase maintained at a pH between about 0 and 2 and a temperature between about 10° and 50° C. to form methylene-bis-iminodiacetonitrile.

Claim 25

The method of claim 20 wherein the strong mineral acid is selected from the group consisting of sulfuric and hydrochloric acid.

Claim 26

The method of preparing methylene-bis-iminodiacetonitrile of claim 20 wherein the ratio of ammonia and formaldehyde utilized in the process is between about 1:1.5 and 1:3 and the ratio of ammonia and hydrogen cyanide is between about 1:1.2 and 1:3.

Claim 27

The method of preparing nitrilotriacetonitrile of claim 5 which comprises reacting methylene-bis-iminodiacetonitrile with hydrogen cyanide and formaldehyde in an aqueous liquid phase mixture at a temperature between about 50° C. and about 95° C. to form nitrilotriacetonitrile.

Claim 28

The method of preparing nitrilotriacetonitrile of claim 23 which comprises reacting methylene-bis-iminodiacetonitrile at a pH between about 0 and about 2 with hydrogen cyanide and formaldehyde to form nitrilotriacetonitrile.

Claim 29

The method of preparing nitrilotriacetonitrile of claim 24 wherein the pH is maintained between about 0 and about 2 by the presence of a strong mineral acid selected from the group consisting of sulfuric and hydrochloric acid.

Claim 32

The method of preparing nitrilotriacetonitrile of claim 26 which comprises; forming a liquid phase adduct of ammonia and formaldehyde, adjusting the pH of said liquid phase between about 0 and 2 by the addition of a mineral acid, adding hydrogen cyanide to said liquid phase maintained at a pH between about 0 and about 2 by the presence of a mineral acid and a temperature between about 10° and 50° C. to form a reaction mixture containing methylene-bis-iminodiacetonitrile and reacting said methylene-bis-iminodiacetonitrile in said reaction mixture with hydrogen cyanide and formaldehyde at a temperature between 50° and about 95° C. and a pH between about 0 and about 2 to form nitrilotriacetonitrile.

Claim 33

The method of preparing nitrilotriacetonitrile of claim 27 wherein said ammonia, formaldehyde and hydrogen cyanide are utilized in a ratio of ammonia:formaldehye of from about 1:1.8 to about 1.3.6 and a ratio of ammonia:hydrogen cyanide of from about 1:1.8 to about 1:3.6.

Claim 34

The method of preparing nitrilotriacetonitrile of claim 15 which comprises forming a liquid phase adduct of ammonia and formaldehyde, adjusting the pH of said liquid phase between about 0 and about 2 by addition of a strong mineral acid adding ammonia and hydrogen cyanide to said liqued phase maintained at a pH between about 0 and about 2 by the presence of a strong mineral acid and at a temperature between about 10° and 50° C. to form a reaction mixture containing methylene-bis-iminodiacetonitrile and adding hydrogen cyanide and ammonia to said reaction mixture maintained at a temperature between 50° and about 95° C. and a pH between about 0 and 2 to form nitrilotriacetonitrile, said ammonia, formaldehyde and hydrogen cyanide are added to the reaction mixture in a ratio of ammonia:formaldehyde of from about 1:1.8 to about 1:3.6 and of ammonia:hydrogen cyanide of from about 1:1.8 to about 1:3.6.

Claim 37

A process for preparing methylenebisiminodiacetonitrile comprising: a. reacting at a temperature below about 50° C. for about 16 minutes to 109 minutes a reaction mixture consisting essentially of; (i) water, (ii) an ammonia source selected from the group consisting of an adduct of ammonia and formaldehyde, the adduct of ammonia and formaldehyde being both an ammonia source and a formaldehyde source; (iii) formaldehyde; (iv) HCN; and (v) a strong mineral acid to maintain the pH of the reaction mixture within the range of about 2 -0, the ammonia source, formaldehyde, and HCN being present in amounts to provide a mole ratio of ammonia:formaldehyde:HCN 1:2.5-3:2-3, and the water being present in a ratio of about 10 to 30 parts by weight of water per part by weight of ammonia, to form a reacted mixture consisting essentially of methylenebisiminodiacetonitrile and an acidic liquor; b. adjusting the temperature of the reacted mixture to about 10-50° C. if it is not already within this range to form a slurry consisting essentially of crude precipitated crystalline methylenebisiminodiacetonitrile and an acidic mother liquor; c. seprating the crude crystalline methylenebisiminodiacetonitrile from the mother liquor while maintaining the temperature of the slurry within the range of about 10° to 50° C.; and d. recovering the separated methylenebisiminodiacetonitrile.

Claim 38

A process for preparing methylenebisiminodiacetonitrile comprising: a. reacting at a temperature below about 50° C. for about 16 minutes to 109 minutes a reaction mixture consisting essentially of; (i) water, (ii) an ammonia source selected from the group consisting of an adduct of ammonia and formaldehyde, the adduct of ammonia and formaldehyde being both an ammonia source and a formaldehyde source; (iii) formaldehyde; (iv) HCN; and (v) a strong mineral acid to maintain the pH of the reaction mixture within the range of about 2 -0, the ammonia source, formaldehyde, and HCN being present in amounts to provide a mole ratio of ammonia:formaldehyde:HCN 1:2.5-3:2-3, and the water being present in a ratio of about 10 to 30 parts by weight of water per part by weight of ammonia, to form a reacted mixture consisting essentially of methylenebisiminodiacetonitrile and an acidic liquor; b. adjusting the temperature of the reacted mixture to about 10-50° C. if it is not already within this range to form a slurry consisting essentially of crude precipitated crystalline methylenebisiminodiacetonitrile and an acidic mother liquor; c. seprating the crude crystalline methylenebisiminodiacetonitrile from the mother liquor while maintaining the temperature of the slurry within the range of about 10° to 50° C.; and d. recovering the separated methylenebisiminodiacetonitrile.

Claim 39

A fully continuous process for preparing methylenebisiminodiacetonitrile comprising: a. charging into a cooled agitated mixing zone, and mixing therein to form an aqueous reaction mixture, reactants consisting essentially of; (i) an ammonia source selected from the group consisting of an adduct of ammonia and formaldehyde, the adduct of ammonia and formaldehyde being both an ammonia source and a formaldehyde source; (ii) an aqueous formaldehyde solution; (iii) a strong mineral acid; and (iv) liquid anhydrous HCN while maintaining the temperature of the reactants in the mixing zone within the rnage of below about 50° C., the mole ratio of ammonia:formaldehyde:HCN in the aqueous reaction mixture being about 1:2.5-3:2-3, the weight ratio of ammonia to water in the aqueous reaction mixture being about 1:10-30; and the pH of the aqueous reaction mixture being about 2-0; b. passing the aqueous reaction mixture through a heated reaction zone, residence time in the reaction zone being about 16-109 minutes, while maintaining the temperature of the aqueous mixture in the reaction zone within the range of below about 50° C. to form a reacted mixture consisting essentially of methylenebisiminodiacetonitrile and an acidic aqueous liquor; c. adjusting the temperature of the reacted mixture to about 10°-50° C. if it is not already within this temperature range to form crude precipitated crystalline methylenebisiminodiacetonitrile and an acidic mother liquor; d. passing the crude precipitated crystalline methylenebisiminodiacetonitrile and the mother liquor through a separating zone to separate the crude crystalline methylenebisiminodiacetonitrile from the mother liquor; and e. recovering the separated methylenebisiminodiacetonitrile.

Claim 40

A fully continuous process for preparing methylenebisiminodiacetonitrile comprising: a. charging into a cooled agitated mixing zone, and mixing therein to form an aqueous reaction mixture, reactants consisting essentially of; (i) an ammonia source selected from the group consisting of an adduct of ammonia and formaldehyde, the adduct of ammonia and formaldehyde being both an ammonia source and a formaldehyde source; (ii) an aqueous formaldehyde solution; (iii) a strong mineral acid; and (iv) liquid anhydrous HCN while maintaining the temperature of the reactants in the mixing zone within the rnage of below about 50° C., the mole ratio of ammonia:formaldehyde:HCN in the aqueous reaction mixture being about 1:2.5-3:2-3, the weight ratio of ammonia to water in the aqueous reaction mixture being about 1:10-30; and the pH of the aqueous reaction mixture being about 2-0; b. passing the aqueous reaction mixture through a heated reaction zone, residence time in the reaction zone being about 16-109 minutes, while maintaining the temperature of the aqueous mixture in the reaction zone within the range of below about 50° C. to form a reacted mixture consisting essentially of methylenebisiminodiacetonitrile and an acidic aqueous liquor; c. adjusting the temperature of the reacted mixture to about 10°-50° C. if it is not already within this temperature range to form crude precipitated crystalline methylenebisiminodiacetonitrile and an acidic mother liquor; d. passing the crude precipitated crystalline methylenebisiminodiacetonitrile and the mother liquor through a separating zone to separate the crude crystalline methylenebisiminodiacetonitrile from the mother liquor; and e. recovering the separated methylenebisiminodiacetonitrile.