Method of making N-(2-methoxyethyl)morpholine

Covers a process of making N-(2-methoxyethyl)morpholine by reacting N-(2-hydroxyethyl)morpholine with an excess of methanol in presence of a silica-alumina catalyst.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The instant invention generally relates to an improved process for making 
N-(2-methoxyethyl)morpholine. 
2. Prior Art 
N-(2-methoxyethyl)morpholine has been found to be a very valuable chemical 
in the catalyst field. It has been found particularly useful as a 
polyurethane catalyst. However, many methods of preparing said chemical 
are relatively expensive, usually involving a metal 
hydrogenation-dehydrogenation catalyst. One such method involves reaction 
of morpholine with ethylene glycol monomethyl ether in presence of 
hydrogen over said metal hydrogenation-dehydrogenation catalyst. 
It would be a distinct advance in the art if a method were found of making 
N-(2-methoxyethyl)morpholine without need to resort to expensive metal 
hydrogenation-dehydrogenation catalyst and concomitant use of hydrogen. 
Such is the primary object of the present invention. Other objects will 
appear hereinafter. 
SUMMARY OF THE INVENTION 
In accordance with the broad aspects of the present invention 
N-(2-methoxyethyl)morpholine is produced by reacting 
N-(2-hydroxyethyl)morpholine with an excess of methanol in presence of a 
silica-alumina catalyst.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In accordance with the preferred embodiments to 
N-(2-methoxyethyl)morpholine is prepared by reacting 
N-(2-hydroxyethyl)morpholine with an excess of methanol in presence of a 
silica-alumina catalyst. The reactants are readily available materials and 
need no further elaboration. Usually the reaction is effected at a 
relatively high temperature under pressure. 
A wide variety of silica-alumina materials may be useful as catalysts here. 
The silica-aluminas which are most effective as catalysts include those 
having an alumina content of from about 5 to about 50 wt.% alumina and 
preferably from about 10 to about 40 wt.% alumina. While silica or alumina 
utilized alone have proven to be poor catalysts for the process of this 
invention, the silica-aluminas as herein described effect the reaction in 
high yields and with high selectivity to the desired product. 
While almost of any silica-alumina with an alumina content within the 
above-mentioned range is effective as a catalyst in the process of this 
invention, particularly desirable are silica-aluminas with surface areas 
of from about 50 m.sup.2 /g to about 700 m.sup.2 /g. 
The silica-alumina catalysts can be employed in any well known form such as 
a fine powder or as a pellet. Pelletized catalysts are particularly 
suitable for continuous processes in which the catalyst may be employed as 
a fixed bed. The particular physical form in which the catalyst is 
employed is not critical in the process of this invention. 
The amount of silica-alumina catalyst employed in the process of this 
instant invention can be widely varied. In batch processes, silica-alumina 
catalysts in an amount of from about 1 to about 20 wt.%, based upon the 
amount of reactants present, have been found satisfactory, with an amount 
of from about 5 to about 10% being preferred. In a continuous reaction 
process wherein the catalyst is generally employed as a fixed bed, a 
weight hourly space velocity (WHSV) of from about 0.1 to 5.0 g/ml 
catalyst/hour is satisfactory with a space velocity of from about 0.2 to 
about 2.0 g/ml catalyst/hour being preferred. 
The reaction of this invention, as described herein, is carried out 
substantially in a liquid phase reaction which is conducted at a 
temperature of from about 200.degree. C. to about 350.degree. C., more 
often 250.degree.-350.degree. C. It has been found that temperatures in 
the range of from about 260.degree. to 300.degree. C. are normally 
sufficient for good yield production of the desired morpholine derivative. 
The pressure at which the reaction is carried out can be any pressure 
sufficient to maintain the reactants substantially in the liquid state. 
Generally, reaction pressure of from about 10 to about 3,000 psig. have 
been found satisfactory. It has been found that for typical reaction 
temperatures the preferable reaction zone pressure is from about 1000 to 
about 2000 psig. 
In practicing the process of this invention a solvent is not required, but 
may be employed if desired. Whenever a solvent is employed, the solvent 
should be nondeleterious to the reaction environment and the desired 
reaction. Examples of suitable solvents include hydrocarbon solvents such 
as hexane, decane, dodecene, benzene, and the like, and chlorinated 
aromatic solvents such as chlorobenzene. 
The crude reaction product obtained from the process of this invention will 
contain the desired N-(2-methoxyethyl)morpholine (MEM) in combination with 
some 2,2'-dimorpholinediethyl ether (DMDEE) and 2,2'-dimorpholine (DMORE) 
and larger amounts of N-methylmorpholine (NMM). 
It has been found that the silica-alumina catalyst may be recovered from 
the crude reaction mixture and recycled for reuse according to the process 
of this invention. It is generally preferable to wash the recovered 
catalyst, for example with methanol and/or water, and dry it prior to 
recycling it for reuse. 
The N-(2-methoxyethyl)morpholine can be recovered from the crude reaction 
mixture by conventional means, for example distillation, extraction, and 
the like. 
The process of this invention will now be further illustrated in the 
following examples which are for the purpose of illustration and should 
not be considered as a limitation on the scope of the invention. 
EXAMPLES 1-3 
A clean and dry 1 liter stirred stainless steel autoclave was charged with 
a solution of 262.3 g (2.0 moles) N-(2-hydroxyethyl)morpholine (HEM) and 
256.0 g (8.0 moles) methanol and then the catalyst. 
A silica-alumina catalyst in an amount of 5.0 wt.% based on weight of 
reactants was employed. The catalyst used was AEROCAT TA sold by American 
Cyanamid which contained 74.4% silica, 25.7% alumina, 0.6% other oxides 
and had a surface area of 550-700 m2/g. 
After purging and padding with nitrogen, the autoclave was sealed and then 
heated to the desired temperature and held for the below indicated length 
of time. After cooling to room temperature, the autoclave was carefully 
vented and the reaction mixture recovered. Results are based on glc 
analysis and Karl Fisher water determination. Products were identified by 
distillation and spectral characterization and results are shown below in 
Table I. 
TABLE I 
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Temp. Press. 
t % HEM % Selectivity 
Run. No. 
.degree.C. 
psig hrs. 
Conv. 
NMM MEM DMDEE 
DMORE 
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1 280 1225-1380 
4.0 
66.5 23.7 
62.4 
6.9 1.5 
2 270 1100-1190 
4.0 
43.7 21.3 
64.6 
7.9 1.8 
3 260 1000-1035 
4.0 
33.0 21.1 
66.2 
8.3 1.5 
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