CA1051928A - Process for preparing n,n-dimethylhydrazine - Google Patents
Process for preparing n,n-dimethylhydrazineInfo
- Publication number
- CA1051928A CA1051928A CA246,275A CA246275A CA1051928A CA 1051928 A CA1051928 A CA 1051928A CA 246275 A CA246275 A CA 246275A CA 1051928 A CA1051928 A CA 1051928A
- Authority
- CA
- Canada
- Prior art keywords
- dimethyl
- hydrazine
- acetylhydrazine
- accordance
- reaction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C243/00—Compounds containing chains of nitrogen atoms singly-bound to each other, e.g. hydrazines, triazanes
- C07C243/10—Hydrazines
- C07C243/12—Hydrazines having nitrogen atoms of hydrazine groups bound to acyclic carbon atoms
- C07C243/14—Hydrazines having nitrogen atoms of hydrazine groups bound to acyclic carbon atoms of a saturated carbon skeleton
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C241/00—Preparation of compounds containing chains of nitrogen atoms singly-bound to each other, e.g. hydrazines, triazanes
- C07C241/02—Preparation of hydrazines
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C241/00—Preparation of compounds containing chains of nitrogen atoms singly-bound to each other, e.g. hydrazines, triazanes
- C07C241/04—Preparation of hydrazides
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method for preparing unsymmetrical dimethyl-hydrazine wherein an acid hydrazide is first reductively alkylated with formaldehyde and the resultant N,N-dimethyl-2-acylhydrazine thereupon cleaved via either basic hydrolysis or hydrazinolysis to provide the desired substituted hydrazine.
A method for preparing unsymmetrical dimethyl-hydrazine wherein an acid hydrazide is first reductively alkylated with formaldehyde and the resultant N,N-dimethyl-2-acylhydrazine thereupon cleaved via either basic hydrolysis or hydrazinolysis to provide the desired substituted hydrazine.
Description
lOS~
BACKGROUND OF THE I~EMTION
Field of the Invention This invention relates to a method for preparing a substituted acyclic diamine.
Description of the Prior Art Unsymmetrical dimethylhydrazine (UDMH) is a versatile chemical intermediate having recognized usefulness in the preparation of surfactants, insecticides, dyes, monimers, etc The most important current use thereof, however, is as such in the field of liquid propellants for rockets.
There presently exists two applicable commercial methods for producing UDMH. The more desirable of these methods, particularly from the standpoint of overall efficiency, involves the hydrogenation of nitrosodimethylamine in turn obtained by nitrosating dimethylamine. This method suffers because nitrosodimethylamine has been identified as such a powerful carcinogen that in order to provide absolute protection for plant workers, an exceedingly expensive plant installation is indicated. The market for UDMH, on the other hand, is not sufficiently large enough to justify such an expenditure.
The other method available for producing UDMH
commercially is in accordance with the Raschig process, which is based upon the reaction of monochloramine with dimethyl-amine. This method, while presenting tedious problems associated with the recovery of the UDMH, poses an additional drawback in that the preparation of monochloramine can lead to the formation of minute quantities of trichloramine. The latter compound is so highly explosive that extreme care must be observed in order to assure that none of this unstable ~O~9Z8 by-product is produced.
Accordingly, there exists an important need for a commercially adaptable method of producing unsymmetrical dimethylhydrazine which is not capital intensive and further-more does not involve the formation of hazardous intermediatesor by-products. The object of this invention is to provide such an improved method.
SUM~RY OF THE INVENTION
In accordance with the present invention a method comprising a two-step procedure is provided for the preparation of unsymmetrical dimethylhydrazine. In the first step of the method an acid hydrazide is reductively alkylated with formaldehyde resulting in the formation of the corresponding N,N-dimethyl-2-acylhydrazine. In the second step the indicated substituted hydrazine is cleaved by either (I) base hydrolysis or (II) reaction with hydrazine to yield the l,l-dimethyl-hydrazine.
The following equation is illustrative of the underlying reactions of the method of this invention.
Il 11 11 RCNHNH2 ~RCNHN(CH3)2~ RC-0 + H2NN(CH3)2 (I) Cat.
~ RCNHNH2 + H2NN(CH3)2 (II) DESCRIPTION OF THE PREFERRED EMBODIMENTS
The acid hydrazides useful in the practice of this invention can be conveniently derived from a lower fatty acid.
The preferred acid hydrazide is acetyl hydrazine which can ,: .
lOS19~8 readily be obtained by reacting a lower ester of acetic acid, preferably the ethyl ester, with hydrazine. The reaction is generally carried out in a lower alcohol of which methanol is most suitable, although solvents are not necessary for effect-ing this reaction. The hydrazine can be anhydrous but foreconomic reasons the conventional 85% hydrazine hydrate of commerce is preferred. The reaction temperature is desirably that of about the boiling point of the ester employed.
Employing the preferred ethyl acetate, such temperature is in the order of 60C. The reactants are preferably combined to provide about a 10~ mole excess of the ester. An alcohol solvent, when employed, is ordinarily used on a basis of about one mole per mole of the ester. Following completion of the reaction, the acid hydrazide solution can be used as is or it can be stripped to remove water, alcohol, unreacted ester or combinations thereof. While the foregoing preparation does not form part of this invention, the working examples will nonetheless illustrate the indicated preferred procedure for obtaining an acid hydrazide from its corresponding fatty acid source.
The first step of the process of this invention consists of reductively alkylating the acid hydrazide with formaldehyde to yield the corresponding N,N-dimethyl-2-acylhydrazine. The formaldehyde can be in the form of an aqueous or methanolic solution thereof although para-formaldehyde serves as well. The preferred form of formaldehyde is Methyl Formcel@(formaldehyde methyl hemiacetal). The acyl hydrazine and formaldehyde can be combined in a molar ratio of from 2 to 3 moles of the formaldehyde per mole of the hydrazine. The preferred molar ratio of the aforesaid ~ 10519Z8 reactants is l mole of the acyl hydrazine to 2.1 moles of formaldehyde.
A suitable temperature range for carrying out the reductive alkylation reaction is from about room temperature to 100C. More preferably, the reaction temperature is maintained within the range of from about 50 to 70C. During the reductive alkylation step hydrogen pressures between about 50 to 150 psig are generally applicable. A closed pressure system is preferred but an open system wherein the reaction mixture is sparged with hydrogen represents an acceptable mode of operation if means are available for recycling hydrogen.
The catalyst useful for effecting reductive alkylation can be the particulate catalytic materials in the form of a Group VIII metal such as palladium, platinum, rhodium, nickel, cobalt and iridium. The usual supports for such catalytic materials can be used, representative of which include carbon, alumina, silica, silica-alumina and titania.
The preferred catalyst in the context of this invention is palladium on a carbon support.
The reductive alkylation reaction can be carried out in the absence of a reaction solvent; that is, in the neat form. The use of a solvent, however, is preferred. The solvent desirably should be a polar solvent of which the lower alkanols and particularly methanol, represent the solvents of choice.
An important feature of this invention resides in the pH control of the reactants during reductive alkylation.
During the course of this reaction the pH should be maintained at not in excess of 7.5. The preferred pH range is in the ~05~9Z~
order of from about 6 to 7, Maintaining the pH as indicated results in a much cleaner reaction than is otherwise obtained and importantly contributes to realizing an essentially quantitative yield and long catalyst life. The pH of the system can be regulated by the addition of an appropriate amount of a lower carboxylic acid such as, for example, acetic or formic acid. Still another applicable pH control acid is phosphoric.
The latter acid may be most advantageously used under those circumstances where corrosion problems associated with the use of the indicated carboxylic acids are presented. Following the completion of the reaction, recovery of the resultant N,N~dimethyl-2-acyl hydrazine can be accomplished by stripping the reaction mixture to remove volatiles. By carrying out the reaction under the preferred conditions noted above, essentially quantitative yields are realized.
Two displacement type procedures exist for convert-ing the substituted acyl hydrazine to unsymmetrical dimethyl hydrazine. Such modes include base hydrolysis and hydrazin-olysis. Base hydrolysis represents the preferred procedure.
For this purpose, a variety of bases are applicable but the alkali metal hydroxides represent the preferred bases, with sodium hydroxide being the base of choice. The amount of base can vary from 1 to 4 moles per mole of the acyl hydrazine.
An aqueous solution of the preferred base; namely, sodium hydroxide, in the order of about 50% concentration is desirably used. The preferred amount of the sodium hydroxide employed in the hydrolysis reaction is about 2 moles per mole of the acyl hydrazine. Suitable temperatures in effecting hydrolysis range from about 60 - 100C. with a temperature in the order of 90 - 100C. being preferred. The unsymmetrical dimethyl ~0~19~8 hydrazine can be conveniently recovered by distillation during the course of the reaction. The time required for effectiny hydrolysis is in the order of several hours. Observing the preferred conditions noted above, yields in excess of 80%
of theoretical are observed.
Another suitable method of displacing the unsymmet-rical dimethyl hydrazine from the acyl hydrazine consists of reacting the latter with anhydrous hydrazine. A broad temperature range for effecting hydrazinolysis is from about 65 - 125C. The preferred temperature is in the order of 100C. An amount of hydrazine ranging from 1 to 10 moles thereof per mole of the acyl hydrazine can be satisfactorily used. The preferred amount, however, ranges from 1 to 5 moles on the indicated basis. Similar to the method of recovering unsymmetrical hydrazine employing base hydrolysis, the desired product can be distilled during the course of displacement reaction. Recovery yields in excess of about 70~ theoretical can be realized in accordance with the hydrazinolysis reaction.
In order to illustrate to thoseskilled in the art the best mode contemplated for carrying out the invention, the following working examples are set forth. It is to be understood that these examples are given solely by way of illustration and accordingly, any enumeration of details set forth therein is not to be interpreted as limiting the invention except as such limitations appear in the appended claims. All parts and percentages are by weight unless otherwise noted.
EXAMPLE I
Hydrazine Formation Into a suitable reaction vessel were charged isopropyl alcohol (8 lbs.) and 85~ hydrazine hydrate (36 lbs.).
~V5~
The mixture was heated to 40C. and ethyl acetate (49 lbs.) was added over a 20 minute period. The temperature climbed slowly to 60C. where it was maintained for four hours. Following completion of the reaction, the mixture was stripped to provide a quantitative yield of acetylhydrazine which crystallized on cooling.
Reductive alkylation Into a suitable pressure reactor were charged acetyl hydrazine (41 lbs.), methanol (40 lbs.) and palladium on carbon catalyst (3.3 lbs.). The reactor was flushed with hydrogen and heated to 45C. and the hydrogen pressure then raised to 100 psig. Over a period of 120 minutes a mixture of Methyl Formcel (80 lbs.~ and acetic acid (4 lbs.) was pumped into the reactor while maintaining the hydrogen pressure constant at about 100 psig. The exothermic reaction was completed about 10 minutes following the addition of the mixture of formaldehyde and acid. The product, N,N-dimethyl acetyl-hydrazine, was formed in essentially quantitative yield and was -isolated by filtration of the catalysts and stripping of the solvent. The product was a colorless liquid at room tempera-ture.
Base Hydrolysis The above reactor was set up for distillation into which was charged N,N-dimethyl acetylhydrazine (56 lbs.) which was then stirred and heated to 90C. over a period of 30 minutes. An aqueous solution of 50% sodium hydroxide ~96 lbs.) was thereupon added. An exothermic reaction occurred and unsymmetrical dimethyl hydrazine was distilled from the reactor. The yield of UDMH was in excess of 80% and the purity thereof without fractionation was in the order of 91%.
~)5~
By analysis the impurities were found to be methylamine 2.2%, methylene-dimethyl hydrazine 2.0% and water 4.7%.
Hydrazinolysis Into a suitable reactor equipped with a distil-lation column were charged 10.2 parts of the N,N-dimethyl acetylhydraæine and 6.75 parts of hydrazine. The mixture was heated to 100C. with stirring and 4.93 parts of UDMH was distilled off. GC analysis indicated the UDMH was 96%
pure representing 74% of theoretical yield.
The pot residue was vacuum stripped and dissolved in an acetylhydrazine mother liquor. The solution was cooled, filtered, washed with isopropanol and dried, thus providing acetylhydrazine for recycle.
EXAMPLE II
Into a 30-gallon reactor fitted with a reflux condenser were charged 57.8 lbs. of ethyl acetate and 35.1 lbs.
of 85% hydrazine hydrate. With stirring the reaction mixture was heated under reflux for ten hours and cooled. Glacial acetic acid was added to the cooled reaction mixture until a pH of 6 was reached, followed by the addition of 1.7 lbs.
of 50% wet power of 5% palladium on carbon. The reactor was then sealed and pressurized to 100 psig with hydrogen.
1~ .
Methyl Formcel containing 5% acetic acid in the amount of 57 lbs. was pumped into the reactor over a period of five hours. Heating was applied and the temperature maintained at 60 - 90C. and the pressure held between 100 - 150 psig during the formaldehyde addition. The reactor was then cooled, vented and the catalyst filtered. Solvents present in the reaction mixture (methanol, ethyl acetate, ethanol) were distilled and recovered. The resulting aqueous 1051~X8 solution of dimethyl acetyl hydrazine was then mixed with 50%
sodium hydroxide in the amount of 68 lbs. and heated carefully at 60C. with reflux cooling. After three hours the reactor was set up for distillation and 99% pure unsymmetrical dimethyl hydrazine was distilled from the mixture. The recovery of said hydrazine was in the order of about 28 lbs.
BACKGROUND OF THE I~EMTION
Field of the Invention This invention relates to a method for preparing a substituted acyclic diamine.
Description of the Prior Art Unsymmetrical dimethylhydrazine (UDMH) is a versatile chemical intermediate having recognized usefulness in the preparation of surfactants, insecticides, dyes, monimers, etc The most important current use thereof, however, is as such in the field of liquid propellants for rockets.
There presently exists two applicable commercial methods for producing UDMH. The more desirable of these methods, particularly from the standpoint of overall efficiency, involves the hydrogenation of nitrosodimethylamine in turn obtained by nitrosating dimethylamine. This method suffers because nitrosodimethylamine has been identified as such a powerful carcinogen that in order to provide absolute protection for plant workers, an exceedingly expensive plant installation is indicated. The market for UDMH, on the other hand, is not sufficiently large enough to justify such an expenditure.
The other method available for producing UDMH
commercially is in accordance with the Raschig process, which is based upon the reaction of monochloramine with dimethyl-amine. This method, while presenting tedious problems associated with the recovery of the UDMH, poses an additional drawback in that the preparation of monochloramine can lead to the formation of minute quantities of trichloramine. The latter compound is so highly explosive that extreme care must be observed in order to assure that none of this unstable ~O~9Z8 by-product is produced.
Accordingly, there exists an important need for a commercially adaptable method of producing unsymmetrical dimethylhydrazine which is not capital intensive and further-more does not involve the formation of hazardous intermediatesor by-products. The object of this invention is to provide such an improved method.
SUM~RY OF THE INVENTION
In accordance with the present invention a method comprising a two-step procedure is provided for the preparation of unsymmetrical dimethylhydrazine. In the first step of the method an acid hydrazide is reductively alkylated with formaldehyde resulting in the formation of the corresponding N,N-dimethyl-2-acylhydrazine. In the second step the indicated substituted hydrazine is cleaved by either (I) base hydrolysis or (II) reaction with hydrazine to yield the l,l-dimethyl-hydrazine.
The following equation is illustrative of the underlying reactions of the method of this invention.
Il 11 11 RCNHNH2 ~RCNHN(CH3)2~ RC-0 + H2NN(CH3)2 (I) Cat.
~ RCNHNH2 + H2NN(CH3)2 (II) DESCRIPTION OF THE PREFERRED EMBODIMENTS
The acid hydrazides useful in the practice of this invention can be conveniently derived from a lower fatty acid.
The preferred acid hydrazide is acetyl hydrazine which can ,: .
lOS19~8 readily be obtained by reacting a lower ester of acetic acid, preferably the ethyl ester, with hydrazine. The reaction is generally carried out in a lower alcohol of which methanol is most suitable, although solvents are not necessary for effect-ing this reaction. The hydrazine can be anhydrous but foreconomic reasons the conventional 85% hydrazine hydrate of commerce is preferred. The reaction temperature is desirably that of about the boiling point of the ester employed.
Employing the preferred ethyl acetate, such temperature is in the order of 60C. The reactants are preferably combined to provide about a 10~ mole excess of the ester. An alcohol solvent, when employed, is ordinarily used on a basis of about one mole per mole of the ester. Following completion of the reaction, the acid hydrazide solution can be used as is or it can be stripped to remove water, alcohol, unreacted ester or combinations thereof. While the foregoing preparation does not form part of this invention, the working examples will nonetheless illustrate the indicated preferred procedure for obtaining an acid hydrazide from its corresponding fatty acid source.
The first step of the process of this invention consists of reductively alkylating the acid hydrazide with formaldehyde to yield the corresponding N,N-dimethyl-2-acylhydrazine. The formaldehyde can be in the form of an aqueous or methanolic solution thereof although para-formaldehyde serves as well. The preferred form of formaldehyde is Methyl Formcel@(formaldehyde methyl hemiacetal). The acyl hydrazine and formaldehyde can be combined in a molar ratio of from 2 to 3 moles of the formaldehyde per mole of the hydrazine. The preferred molar ratio of the aforesaid ~ 10519Z8 reactants is l mole of the acyl hydrazine to 2.1 moles of formaldehyde.
A suitable temperature range for carrying out the reductive alkylation reaction is from about room temperature to 100C. More preferably, the reaction temperature is maintained within the range of from about 50 to 70C. During the reductive alkylation step hydrogen pressures between about 50 to 150 psig are generally applicable. A closed pressure system is preferred but an open system wherein the reaction mixture is sparged with hydrogen represents an acceptable mode of operation if means are available for recycling hydrogen.
The catalyst useful for effecting reductive alkylation can be the particulate catalytic materials in the form of a Group VIII metal such as palladium, platinum, rhodium, nickel, cobalt and iridium. The usual supports for such catalytic materials can be used, representative of which include carbon, alumina, silica, silica-alumina and titania.
The preferred catalyst in the context of this invention is palladium on a carbon support.
The reductive alkylation reaction can be carried out in the absence of a reaction solvent; that is, in the neat form. The use of a solvent, however, is preferred. The solvent desirably should be a polar solvent of which the lower alkanols and particularly methanol, represent the solvents of choice.
An important feature of this invention resides in the pH control of the reactants during reductive alkylation.
During the course of this reaction the pH should be maintained at not in excess of 7.5. The preferred pH range is in the ~05~9Z~
order of from about 6 to 7, Maintaining the pH as indicated results in a much cleaner reaction than is otherwise obtained and importantly contributes to realizing an essentially quantitative yield and long catalyst life. The pH of the system can be regulated by the addition of an appropriate amount of a lower carboxylic acid such as, for example, acetic or formic acid. Still another applicable pH control acid is phosphoric.
The latter acid may be most advantageously used under those circumstances where corrosion problems associated with the use of the indicated carboxylic acids are presented. Following the completion of the reaction, recovery of the resultant N,N~dimethyl-2-acyl hydrazine can be accomplished by stripping the reaction mixture to remove volatiles. By carrying out the reaction under the preferred conditions noted above, essentially quantitative yields are realized.
Two displacement type procedures exist for convert-ing the substituted acyl hydrazine to unsymmetrical dimethyl hydrazine. Such modes include base hydrolysis and hydrazin-olysis. Base hydrolysis represents the preferred procedure.
For this purpose, a variety of bases are applicable but the alkali metal hydroxides represent the preferred bases, with sodium hydroxide being the base of choice. The amount of base can vary from 1 to 4 moles per mole of the acyl hydrazine.
An aqueous solution of the preferred base; namely, sodium hydroxide, in the order of about 50% concentration is desirably used. The preferred amount of the sodium hydroxide employed in the hydrolysis reaction is about 2 moles per mole of the acyl hydrazine. Suitable temperatures in effecting hydrolysis range from about 60 - 100C. with a temperature in the order of 90 - 100C. being preferred. The unsymmetrical dimethyl ~0~19~8 hydrazine can be conveniently recovered by distillation during the course of the reaction. The time required for effectiny hydrolysis is in the order of several hours. Observing the preferred conditions noted above, yields in excess of 80%
of theoretical are observed.
Another suitable method of displacing the unsymmet-rical dimethyl hydrazine from the acyl hydrazine consists of reacting the latter with anhydrous hydrazine. A broad temperature range for effecting hydrazinolysis is from about 65 - 125C. The preferred temperature is in the order of 100C. An amount of hydrazine ranging from 1 to 10 moles thereof per mole of the acyl hydrazine can be satisfactorily used. The preferred amount, however, ranges from 1 to 5 moles on the indicated basis. Similar to the method of recovering unsymmetrical hydrazine employing base hydrolysis, the desired product can be distilled during the course of displacement reaction. Recovery yields in excess of about 70~ theoretical can be realized in accordance with the hydrazinolysis reaction.
In order to illustrate to thoseskilled in the art the best mode contemplated for carrying out the invention, the following working examples are set forth. It is to be understood that these examples are given solely by way of illustration and accordingly, any enumeration of details set forth therein is not to be interpreted as limiting the invention except as such limitations appear in the appended claims. All parts and percentages are by weight unless otherwise noted.
EXAMPLE I
Hydrazine Formation Into a suitable reaction vessel were charged isopropyl alcohol (8 lbs.) and 85~ hydrazine hydrate (36 lbs.).
~V5~
The mixture was heated to 40C. and ethyl acetate (49 lbs.) was added over a 20 minute period. The temperature climbed slowly to 60C. where it was maintained for four hours. Following completion of the reaction, the mixture was stripped to provide a quantitative yield of acetylhydrazine which crystallized on cooling.
Reductive alkylation Into a suitable pressure reactor were charged acetyl hydrazine (41 lbs.), methanol (40 lbs.) and palladium on carbon catalyst (3.3 lbs.). The reactor was flushed with hydrogen and heated to 45C. and the hydrogen pressure then raised to 100 psig. Over a period of 120 minutes a mixture of Methyl Formcel (80 lbs.~ and acetic acid (4 lbs.) was pumped into the reactor while maintaining the hydrogen pressure constant at about 100 psig. The exothermic reaction was completed about 10 minutes following the addition of the mixture of formaldehyde and acid. The product, N,N-dimethyl acetyl-hydrazine, was formed in essentially quantitative yield and was -isolated by filtration of the catalysts and stripping of the solvent. The product was a colorless liquid at room tempera-ture.
Base Hydrolysis The above reactor was set up for distillation into which was charged N,N-dimethyl acetylhydrazine (56 lbs.) which was then stirred and heated to 90C. over a period of 30 minutes. An aqueous solution of 50% sodium hydroxide ~96 lbs.) was thereupon added. An exothermic reaction occurred and unsymmetrical dimethyl hydrazine was distilled from the reactor. The yield of UDMH was in excess of 80% and the purity thereof without fractionation was in the order of 91%.
~)5~
By analysis the impurities were found to be methylamine 2.2%, methylene-dimethyl hydrazine 2.0% and water 4.7%.
Hydrazinolysis Into a suitable reactor equipped with a distil-lation column were charged 10.2 parts of the N,N-dimethyl acetylhydraæine and 6.75 parts of hydrazine. The mixture was heated to 100C. with stirring and 4.93 parts of UDMH was distilled off. GC analysis indicated the UDMH was 96%
pure representing 74% of theoretical yield.
The pot residue was vacuum stripped and dissolved in an acetylhydrazine mother liquor. The solution was cooled, filtered, washed with isopropanol and dried, thus providing acetylhydrazine for recycle.
EXAMPLE II
Into a 30-gallon reactor fitted with a reflux condenser were charged 57.8 lbs. of ethyl acetate and 35.1 lbs.
of 85% hydrazine hydrate. With stirring the reaction mixture was heated under reflux for ten hours and cooled. Glacial acetic acid was added to the cooled reaction mixture until a pH of 6 was reached, followed by the addition of 1.7 lbs.
of 50% wet power of 5% palladium on carbon. The reactor was then sealed and pressurized to 100 psig with hydrogen.
1~ .
Methyl Formcel containing 5% acetic acid in the amount of 57 lbs. was pumped into the reactor over a period of five hours. Heating was applied and the temperature maintained at 60 - 90C. and the pressure held between 100 - 150 psig during the formaldehyde addition. The reactor was then cooled, vented and the catalyst filtered. Solvents present in the reaction mixture (methanol, ethyl acetate, ethanol) were distilled and recovered. The resulting aqueous 1051~X8 solution of dimethyl acetyl hydrazine was then mixed with 50%
sodium hydroxide in the amount of 68 lbs. and heated carefully at 60C. with reflux cooling. After three hours the reactor was set up for distillation and 99% pure unsymmetrical dimethyl hydrazine was distilled from the mixture. The recovery of said hydrazine was in the order of about 28 lbs.
Claims (10)
1. A method for preparing 1,1-dimethyl hydrazine which comprises the steps:
(a) reductively alkylating an acid hydrazide of the formula wherein R represents lower alkyl with formaldehyde at a pH less than about 7.5 to provide the corresponding N,N-dimethyl-2-acylhydrazine;
(b) cleaving said N,N-dimethyl-2-acylhydrazine by the base hydrolysis or the hydrazinolysis thereof; and (c) recovering the 1,1-dimethyl hydrazine from the reaction mixture of step (b).
(a) reductively alkylating an acid hydrazide of the formula wherein R represents lower alkyl with formaldehyde at a pH less than about 7.5 to provide the corresponding N,N-dimethyl-2-acylhydrazine;
(b) cleaving said N,N-dimethyl-2-acylhydrazine by the base hydrolysis or the hydrazinolysis thereof; and (c) recovering the 1,1-dimethyl hydrazine from the reaction mixture of step (b).
2. A process in accordance with claim 1, wherein said acid hydrazide is acetylhydrazine and wherein said reductive alkylation is effected at a temperature from about 20 - 100°C.
and at a pH of from about 6 - 7.
and at a pH of from about 6 - 7.
3. A process in accordance with claim 2, wherein said acetylhydrazine and the formaldehyde are present in molar ratio of from about 1:2::1:3, respectively, and the reaction temperature is from about 50 - 70°C.
4. A process in accordance with claim 3, wherein the acetylhydrazine and formaldehyde are present in the molar ratio of 1:2.1, respectively.
5. A process in accordance with claim 4, wherein said step (b) the N,N-dimethyl-2-acetylhydrazine is cleaved under base hydrolysis conditions provided by the presence of aqueous sodium hydroxide.
6. A process in accordance with claim 5, wherein the molar ratio of N,N-dimethyl-2-acetylhydrazine to sodium hydroxide is from 1:1::1:4, respectively.
7. A process in accordance with claim 6, wherein the molar ratio of N,N-dimethyl-2-acetylhydrazine to sodium hydroxide is about 1:2, respectively.
8. A process in accordance with claim 4, wherein said step (b) the N,N-dimethyl-2-acetylhydrazine is cleaved by reaction with hydrazine.
9. A process in accordance with claim 8, wherein said hydrazine is anhydrous and is present in the amount to provide a molar ratio of N,N-dimethyl-2-acetylhydrazine to hydrazine of from 1:1::1:10, respectively.
10. A process in accordance with claim 9, wherein the molar ratio of N,N-dimethyl-2-acetylhydrazine to hydrazine is from 1:5, respectively.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US55975575A | 1975-03-19 | 1975-03-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1051928A true CA1051928A (en) | 1979-04-03 |
Family
ID=24234890
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA246,275A Expired CA1051928A (en) | 1975-03-19 | 1976-02-20 | Process for preparing n,n-dimethylhydrazine |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS51115407A (en) |
| BE (1) | BE839664A (en) |
| CA (1) | CA1051928A (en) |
| DE (1) | DE2611724C3 (en) |
| FR (1) | FR2304599A1 (en) |
| GB (1) | GB1488637A (en) |
| IT (1) | IT1062084B (en) |
| MX (1) | MX3256E (en) |
| NL (1) | NL7602794A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USRE43252E1 (en) | 1992-10-27 | 2012-03-20 | Vast Power Portfolio, Llc | High efficiency low pollution hybrid Brayton cycle combustor |
-
1976
- 1976-02-20 CA CA246,275A patent/CA1051928A/en not_active Expired
- 1976-02-26 MX MX2576U patent/MX3256E/en unknown
- 1976-03-09 IT IT2100676A patent/IT1062084B/en active
- 1976-03-17 GB GB1075076A patent/GB1488637A/en not_active Expired
- 1976-03-17 BE BE165252A patent/BE839664A/en not_active IP Right Cessation
- 1976-03-17 NL NL7602794A patent/NL7602794A/en unknown
- 1976-03-18 FR FR7607882A patent/FR2304599A1/en active Granted
- 1976-03-19 DE DE19762611724 patent/DE2611724C3/en not_active Expired
- 1976-03-19 JP JP2938976A patent/JPS51115407A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USRE43252E1 (en) | 1992-10-27 | 2012-03-20 | Vast Power Portfolio, Llc | High efficiency low pollution hybrid Brayton cycle combustor |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1062084B (en) | 1983-06-25 |
| JPS51115407A (en) | 1976-10-12 |
| NL7602794A (en) | 1976-09-21 |
| JPS5716978B2 (en) | 1982-04-08 |
| BE839664A (en) | 1976-07-16 |
| DE2611724A1 (en) | 1977-02-10 |
| DE2611724B2 (en) | 1978-09-28 |
| GB1488637A (en) | 1977-10-12 |
| MX3256E (en) | 1980-08-12 |
| FR2304599A1 (en) | 1976-10-15 |
| FR2304599B1 (en) | 1978-11-17 |
| DE2611724C3 (en) | 1979-05-23 |
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