Process for the preparation of N,N′-dialkylalkanediamines

Details Process for the preparation of N,N′-dialkylalkanediamines Process for the preparation of N,N′-dialkylalkanediamines

2000-10-20

2001-06-05

Richter, Johann (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Amino nitrogen containing

Reexamination Certificate

active

06242651

ABSTRACT:

TECHNICAL FIELD
This application is a 371 of PCT JP00/01576 filed Mar. 15, 2000.
The present invention relates to a novel preparation process of N,N′-dialkylalkanediamine. More particularly, in the preparation of the N,N′-dialkylalkanediamine by reaction of dihaloalkane with lower alkylamine, the invention relates to a process for preparing desired N,N′-dialkylalkanediamine in a high yield by inhibiting formation of unfavorable by-products such as cyclic dialkyldiamine and trialkylalkanetriamine.
BACKGROUND ART
The preparation process of N,N′-dialkylalkanediamine has been known for a long time, and many processes have been proposed. For example, J. uber die Fortshritteder Chemie, 389(1859) has reported a process for preparing N,N′-diethyl-1,2-ethanediamine by reacting dibromoalkane with alkylamine.
A process for obtaining N,N′-dimethyl-1,2-propanediamine has been described in J. Chem. Soc., 214(1947).
Further, processes for preparing N,N′-dimethyl-1,3-propanediamine and N,N′-dimethyl-1,2-ethanediamine have also been known.
Japan Laid Open Patent SHO 57-120570 has disclosed a process for preparing 1,3-dimethyl-2-imidazolidinone via N,N′-dimethyl-1,2-ethanediamine as an intermediate by reacting 1,2-dichloroethane, water, liquid methylamine and carbon dioxide in an autoclave.
Further, a reaction of dichloroalkane with primary lower alkylamine has been found as a process for preparing N,N′-dialkylalkanediamine. Various investigations have been carried out on the reaction. For example, a process for carrying out the reaction in the presence of a nickel compound and/or copper compound and a process for carrying out the reaction substantially in the absence of moisture have been proposed in Japan Laid Open Patent SHO 62-129256.
These processes for preparing N,N′-dialkylalkanediamine by reaction of dihaloalkane and alkylamine can provide the desired product in a high yield and thus are favorable processes.
The processes can provide N,N′-dialkylalkanediamine in a yield of 80 to 85%. However, 1 to 5% of cyclic dialkyldiamine and 9 to 13% of trialkylalkanetriamine are formed as impurities at the same time. The whole amount of impurities including other by-products is considerably large. As a result, enhancement of equipment has been required for the purification of thus obtained N,N′-dialkylalkanediamine.
Consequently, as to the preparation of N,N′-dialkylalkanediamine, it has been desired to develop a process which can inhibit formation of cyclic dialkyldiamine, trialkylalkanetriamine and other impurities and can provide high purity N,N′dialkylalkanediamine in a high yield. It has also been demanded that N,N′-alkylalkanediamine is produced by such a process in order to simplify the purification operation.
DISCLOSURE OF INVENTION
One object of the invention is to solve the above problems on the known preparation process of N,N′-dialkylalkanediamine and to increase the yield of N,N′-dialkylalkanediamine.
Another object of the invention is to provide a novel preparation process of N,N′-dialkylalkanediamine which can inhibit formation of cyclic dialkyldiamine and trialkylalkanetriamine, can give high purity and high yield, and has no requirement to make purification equipment complex and large scale.
The present inventors have carried out an intensive investigation in order to solve the above problems. That is, various investigations have been carried out on the reaction between dihaloalkane and alkylamine. The reaction mechanism was elucidated in the main reaction and a side reaction for forming cyclic dialkyldiamine and trialkylalkanetriamine. On the basis of these investigation results, the present invention, that is, a preparation process of N,N′-dialkylalkanediamine has been completed.
On the basis of the elucidated mechanism on the main reaction for forming the desired product and the side reaction for forming the by-products, the present inventors have found that a haloalkaneamine intermediate generates in the course of forming N,N′-dialkylalkanediamine by reaction of dihaloalkane and alkylamine, and that the object of the invention can be achieved by proceeding the reaction while controlling the residual amount of haloalkaneamine intermediate in the reaction system, that is, concentration in the reaction mixture. Thus the present invention has been completed.
In the process of the invention, the haloalkaneamine intermediate formed by reaction of dihaloalkane and alkylamine is controlled to 0.002 mol or less, preferably 0.001 mol or less per 1 mol of alkylamine in the reaction system. Further, the object of the invention can be achieved by reacting the haloalkaneamine intermediate with alkylamine which serves as a solvent. The embodiment for realizing the process is dropwise addition of dihaloalkane in a batch type reactor or use of vessel type continuous reactor, preferably, multistage vessel type continuous reactor, more preferably tubular continuous reactor.
In the process, alkylamine and dihaloalkane are charged to the reactor, dihaloalkane is preferably added continuously or by portions, the reaction is proceeded with controlling the amount of haloalkaneamine intermediate in the above range, formation of cyclic dialkyldiamine and trialkylalkanetriamine is inhibited, and thus high purity N,N′-dialkylalkanediamine can be obtained in a high yield.
That is, the aspect of the present invention is illustrated below.
(1) A preparation process of N,N′-dialkylalkanediamine by reacting dihaloalkane represented by the formula (1):
wherein R
1
and R
2
are a hydrogen atom or a lower alkyl group, X is a chlorine, bromine or iodine atom, and n is an integer of 2 to 6, with lower alkylamine represented by the formula (2):
R—NH
2
  (2)
wherein R is a lower alkyl group, to obtain N,N′-dialkylalkanediamine represented by the formula (3):
wherein R
1
and R
2
are a hydrogen atom or a lower alkyl group, X is a chlorine, bromine or iodine atom, and n is an integer of 2 to 6, characterized in that the reaction is carried out with controlling the residual amount of haloalkaneamine intermediate represented by the formula (4):
wherein R is a lower alkyl group, R
1
and R
2
are a hydrogen atom or lower alkyl group, X is a chlorine, bromine or iodine atom, and n is an integer of 2 to 6, to 0.002 mol or less for 1 mol of lower alkylamine represented by the formula (2).
(2) A preparation process according to item (1) wherein the lower alkylamine represented by the formula (2) is used in amount of 5 mols or more for 1 mol of dihaloalkane represented by the formula (1).
(3) A preparation process according to item (1) wherein the reaction of dihaloalkane with lower alkylamine is carried out by dropwise addition of dihaloalkane to lower alkylamine in a batch reactor.
(4) A preparation process according to item (1) wherein the reaction of dihaloalkane with lower alkylamine is carried out in a vessel type continuous reactor or a tubular continuous reactor.
(5) A preparation process according to item (1) wherein the reaction of dihaloalkane with lower alkylamine is carried out in a multistage vessel type continuous reactor.
(6) A preparation process according to item (1) wherein the reaction of dihaloalkane with lower alkylamine is carried out in a tubular continuous reactor.
(7) A preparation process according to item (6) wherein the reaction is carried out by feeding dihaloalkane represented by the formula (1) and lower alkylamine represented by the formula (2) to a tubular continuous reactor, and dihaloalkane is added by portions or continuously at a position capable of controlling a residual amount in the reactor tube of haloalkaneamine represented by the formula (4), to 0.002 mol or less for 1 mol of lower alkylamine.
(8) A preparation process according to one of items 1 to 7 wherein the residual amount in the reaction system of haloalkaneamine represented by the formula (4) is 0.001 mol or less for 1 mol of lower alkylamine represented by the formula

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