Chemical process

Claim 2

IN A PROCESS FOR PRODUCING NITRILOTRIACETONITRILE FROM AMMONIA, FORMALDEHYDE, HYDROGEN CYANIDE, AND A STRONG MINERAL ACID, THE IMPROVEMENT WHEREIN: A. AT LEAST ONE OF SAID REACTANTS IS COMBINED WITH THE OTHER REACTANTS AND AT LEAST PARTIALLY REACTED THEREWITH IN AN AQUEOUS SYSTEM IN A FIRST REACTION ZONE AT A PH AT LEAST AS ACIDIC AS ABOUT 2.0 AT A TEMPERATURE FROM ABOUT 120* TO ABOUT 250*F, WHEREIN THE REACTION TO NITRILOTRIACETONITRILE IS LESS THAN COMPLETE, PRODUCING AN EFFLUENT, B. THE EFFLUENT FROM SAID FIRST REACTION ZONE IS REDUCED IN TEMPERATURE BY AT LEAST ABOUT 10*F SO THAT THE RESULTANT TEMPERATURE THEREOF IS WITHIN THE RANGE FROM ABOUT 50* TO ABOUT 150*F, AND C. THE COOLED EFFLUENT IS REACTED SUBSTANTIALLY COMPLETELY AT A TEMPERATURE FROM ABOUT 150* TO ABOUT 250*F TO PRODUCE NITRILOTRIACETONITRILE, THE HEAT CAPACITY OF THE REDUCED TEMPERATURE EFFLUENT BEING UTILIZED TO ABSORB AT LEAST A PART OF THE HEAT LIBERATED AT THIS STEP OF THE REACTION TO HOLD THE TEMPERATURE WITHIN THE RANGE SPECIFIED.

Claim 3

The improvement of claim 1 wherein the strong mineral acid is sulfuric acid which is fed with at least part of the ammonia in the form of ammonium sulfate.

Claim 4

The improvement of claim 1 wherein the strong mineral acid is sulfuric acid which is fed with at least part of the ammonia in the form of ammonium sulfate prereacted with formaldehyde, and wherein the hydrogen cyanide is combined with the ammonium sulfate-formaldehyde system in the first reaction zone.

Claim 5

The improvement of claim 3 wherein from about one-fourth to about three-fourths of the heat of reaction of the ammonium sulfate-formaldehyde system with hydrogen cyanide is liberated in the first reaction zone.

Claim 6

The improvement of claim 3 wherein about half of the heat of reaction of the ammonium sulfate-formaldehyde system with hydrogen cyanide is liberated in the first reaction zone.

Claim 7

The improvement of claim 4 wherein the maximum temperature reached in the second zone is controlled by adjusting the amount of temperature reduction in Step B.

Claim 8

The improvement of claim 4 wherein the temperature of the first reaction zone is from about 130* to about 170*F.

Claim 9

The improvement of claim 4 wherein the temperature of the second Reaction zone is from about 170* to about 190*F.

Claim 10

A process for producing nitrilotriacetonitrile (NTN) which comprises: A. forming at a temperature from about 50* to about 120*F an aqueous system of ammonium ion (NH4) , sulfate ion (SO4) , and formaldehyde (CH2O) wherein the mol ratio of (CH2O) to (NH4) is from about 2.9:1 to about 3.1:1, and the mol ratio (SO4) to (NH4) is from about 0.175 to about 0.5, B. reacting said system with hydrogen cyanide (HCN) wherein the mol ratio of (HCN) to ammonium ion (NH4) is from about 2.9:1 to about 3.1:1, said reacting being a contact period of from about one second to about one hour at a temperature from about 120* to about 175*F during which period substantially complete reaction of HCN occurs and from about one-fourth to about three-fourths of the total heat of reaction of the system with hydrogen cyanide to nitrilotriacetonitrile is liberated, C. reducing the temperature of the effluent from the reacting step at least about 10*F to a temperature from about 50* to about 150*F, D. reacting the temperature reduced effluent from C for a period of time from about ten minutes to about 6 hours during which the temperature of the effluent rises at least 10*F and without exceeding a selected temperature of from about 150* to about 250*F, said period of time being of sufficient duration to produce substantially complete reaction to nitrilotriacetonitrile, and wherein E. at least part of the heat of reaction liberated at D is absorbed by the heating-up of the temperature reduced effluent from C to the selected temperature of step D.

Claim 11

A process for producing nitrilotriacetonitrile (NTN) which comprises: A. forming at a temperature from about 50* to about 120*F an aqueous system of ammonium ion (NH4) , sulfate ion (SO4) , and formaldehyde (CH2O) wherein the mol ratio of (CH2O) to (NH4) is from about 2.9:1 to about 3.1:1, and the mol ratio (SO4) to (NH4) is from about 0.175 to about 0.5, B. reacting said system with hydrogen cyanide (HCN) wherein the mol ratio of (HCN) to ammonium ion (NH4) is from about 2.9:1 to about 3.1:1, said reacting being a contact period of from about one second to about one hour at a temperature from about 120* to about 175*F during which period substantially complete reaction of HCN occurs and from about one-fourth to about three-fourths of the total heat of reaction of the system with hydrogen cyanide to nitrilotriacetonitrile is liberated, C. reducing the temperature of the effluent from the reacting step at least about 10*F to a temperature from about 50* to about 150*F, D. reacting the temperature reduced effluent from C for a period of time from about ten minutes to about 6 hours during which the temperature of the effluent rises at least 10*F and without exceeding a selected temperature of from about 150* to about 250*F, said period of time being of sufficient duration to produce substantially complete reaction to nitrilotriacetonitrile, and wherein E. at least part of the heat of reaction liberated at D is absorbed by the heating-up of the temperature reduced effluent from C to the selected temperature of step D.

Claim 12

The process of claim 9 wherein solid nitrilotriacetonitrile is recovered from the product of Step D by crystallization and separation of the crystals producing a mother liquor and wherein at least a part of said mother liquor is cooled to a temperature below that of Step D and is recycled to Step D to provide additional capacity for absorbing the heat of reaction liberated at D.

Claim 13

In a process for producing nitrilotriacetonitrile from ammonia, formaldehyde, hydrogen cyanide, and a strong mineral acid, the improvement wherein: A. at least one of said reactants is combined with the other reactants and at least partially reacted therewith in an aqueous system in a first reaction zone at a pH at least as acidic as about 2.0 at a temperature from about 120* to about 250*F, wherein the reaction to nitrilotriacetonitrile is less than complete, producing an effluent, B. the effluent from said first reaction zone is reduced in temperature by at least about 10*F so that the resultant temperature thereof is within the range from about 50* to about 150*F, and C. the cooled effluent is reacted substantially completely to produce nitrilotriacetonitrile at a temperature from about 150* to about 250*F, the temperature rise in step C being limited at least in part by the heat required to raise the reduced temperature effluent from step B to the temperature of step C.

Claim 14

In a process for producing nitrilotriacetonitrile from ammonia, formaldehyde, hydrogen cyanide, and a strong mineral acid, the improvement wherein: A. at least one of said reactants is combined with the other reactants and at least partially reacted therewith in an aqueous system in a first reaction zone at a pH at least as acidic as about 2.0 at a temperature from about 120* to about 250*F, wherein the reaction to nitrilotriacetonitrile is less than complete, producing an effluent, B. the effluent from said first reaction zone is reduced in temperature by at least about 10*F so that the resultant temperature thereof is within the range from about 50* to about 150*F, and C. the cooled effluent is reacted substantially completely to produce nitrilotriacetonitrile at a temperature from about 150* to about 250*F, the temperature rise in step C being limited at least in part by the heat required to raise the reduced temperature effluent from step B to the temperature of step C.