U.S. patent application number 12/468585 was filed with the patent office on 2010-11-25 for production of n,n-dialklylaminoethyl (meth)acrylates.
Invention is credited to Larry E. Brammer, JR., Barbara E. Fair, Cheng-Sung Huang, Linh Quach, Peter E. Reed, Leonard M. Ver Vers.
Application Number | 20100298594 12/468585 |
Document ID | / |
Family ID | 43034808 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100298594 |
Kind Code |
A1 |
Brammer, JR.; Larry E. ; et
al. |
November 25, 2010 |
PRODUCTION OF N,N-DIALKLYLAMINOETHYL (METH)ACRYLATES
Abstract
A method and apparatus for preparing a N,N-dialkylaminoalkyl
acrytate in a continuous transesterification reaction. The reaction
involves adding alkyl acrylates such as methacrylate or ethacrylate
to a reboiler mechanism and efficiently removing alcohol
co-products. Because the reaction is continuous, the alkyl
acrylates can be added as needed to increase output, decrease
output, or fine-tune the reaction dynamics. An entrainer is used to
form a volatile azeotrope which contains both alcohol and entrainer
and which is easily removed from the reboiler mechanism. This
method reduces the amount of entrainer needed per unit of alkyl
acrylate used and eliminates any need to purify the end product
from entrainer contamination of the resulting N,N-dialkylaminoalkyl
acrylate product.
Inventors: |
Brammer, JR.; Larry E.;
(Kingsport, TN) ; Fair; Barbara E.; (Lisle,
IL) ; Huang; Cheng-Sung; (Naperville, IL) ;
Quach; Linh; (Arlington Heights, IL) ; Reed; Peter
E.; (Plainfield, IL) ; Ver Vers; Leonard M.;
(Downers Grove, IL) |
Correspondence
Address: |
NALCO COMPANY
1601 W. DIEHL ROAD
NAPERVILLE
IL
60563-1198
US
|
Family ID: |
43034808 |
Appl. No.: |
12/468585 |
Filed: |
May 19, 2009 |
Current U.S.
Class: |
560/217 |
Current CPC
Class: |
C07C 213/06 20130101;
C07C 213/06 20130101; C07C 219/08 20130101 |
Class at
Publication: |
560/217 |
International
Class: |
C07C 67/03 20060101
C07C067/03 |
Claims
1. A method of preparing a N,N-dialkylaminoalkyl acrylate of
Formula 1: ##STR00006## wherein R.sub.1 is H, or C.sub.1-C.sub.4
alkyl; R.sub.2 is C.sub.1-C.sub.4 alkylene; and R.sub.3 and R.sub.4
are C.sub.1-C.sub.4 alkyl, comprising: a) providing a distillation
reactor comprising a distillation column and a reboiler; b)
continuously adding to the distillation column, entrainer,
catalyst, polymerization inhibitor, and an alkyl acrylate of
Formula 2 ##STR00007## wherein R.sub.5 is C.sub.1-C.sub.4 alkyl and
a dialkylamino alcohol of Formula 3 ##STR00008## under conditions
resulting in the transesterification of the alkyl acrylate with
said dialkylamino alcohol to form said N,N-dialkylaminoalkyl
acrylate and an alcohol of formula R.sub.5OH; and c) simultaneously
removing an azeotropic mixture of the entrainer and the alcohol
from the distillation column and removing the N,N-dialkylaminoalkyl
acrylate from the reboiler.
2. The method of claim 1 wherein R.sub.1 is H or methyl, R.sub.2 is
ethylene and R.sub.3, R.sub.4 and R.sub.5 are methyl.
3. The method of claim 2 in which the entrainer is selected from
the list consisting of methylpentatne, hexane, heptane, C4-C8
straight chain hydrocarbons, C4-C8 cyclic hydrocarbons, C4-C8
branched hydrocarbons, and any combination thereof.
4. The method of claim 3 wherein the catalyst is one item selected
from the list consisting of strong acids, strong bases, tin-based
Lewis acids, titanium based Lewis acids, and tin catalysts that
exist as liquids at room temperature and which are highly soluble
in the reaction medium, DBTA, and any combination thereof.
5. The method of claim 4 wherein the entrainer, catalyst,
inhibitor, dialkylamino alcohol and alkyl acrylate are added to the
reboiler.
6. The method of claim 4 wherein the entrainer, catalyst, inhibitor
and dialkylamino alcohol are added to the distillation column and
the alkyl acrylate is added to the reboiler.
7. The method of claim 1 wherein the distillation column comprises
between 1 and 60 distillation trays arranged sequentially from a
bottom of the column to a top of a column.
8. The method of claim 7 wherein one item selected from the list of
the entrainer, the catalyst, and the inhibitor are fed into the
distillation column at a position lower than a middlemost
distillation tray.
9. The method of claim 4 where R.sub.1 is H, the molar feed ratio
of methyl acrylate to N,N-dimethylaminoethanol is less than or
equal to 1.7, and the chemical conversion of
N,N-dimethylaminoethanol to N,N-dimethylaminoethyl acrylate is
greater than 88%
10. The method of claim 1 in which there is substantially no
entrainer mixed with the N,N-dialkylaminoalkyl acrylate when the
N,N-dialkylaminoalkyl acrylate is removed from the reboiler.
11. The method of claim 10 in which the pressure within the
distillation column is within the range of 14-14.4 psia.
12. The method of claim 1 in which the reboiler is a kettle
reboiler.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] None.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
BACKGROUND OF THE INVENTION
[0003] This invention relates to a continuous process for preparing
N,N-dialkylaminoalkyl(meth)acrylates by transesterification of an
alkyl(meth)acrylate with a dialkylamino alcohol in the presence of
catalyst and entrainer to form the
N,N-dialkylaminoalkyl(meth)acrylate and byproduct alcohol in which
an azeotropic mixture of entrainer and byproduct alcohol is
continuously removed from the transesterification, to equipment for
performing the transesterification and to equipment and methods for
purifying the N,N-dialkylaminoalkyl(meth)acrylate.
[0004] A number of previous approaches have been taken for
preparing N,N-dialkylaminoalkyl(meth)acrylates. In Japanese Patent
Application 2001/172234 A2 a hexane entrainer is used in a series
of distillation towers which is washed with water, separated in a
decanter, and returned to a column. In Japanese Patent Application
2001/172235 number of serial reaction towers are used with
purification column, in Japanese Patent Application 2001/172236 A
two columns are used, one which removes excess methyl acrylate and
one which removes excess DMAE from the catalyst and other heavy
components with an evaporator, US Published Patent Application
2004/0168903 A1 describes using 3 or 4 distillation columns that
sequentially react then separate the products, US Published Patent
Application 2004/0171868 A1 describes a process in which lower
alcohol co-products are removed along with lower (meth)acrylate and
is then fed into a plant to convert the alcohol co-products back
into methyl acrylate, U.S. Pat. No. 6,437,173 describes using a
titanium catalyst along with three distillation columns, Published
PCT Application WO 2003/093218 A1 describes a tubular piston
reaction technology, U.S. Pat. No. 6,417,392 describes removing
alcohol co-products as (meth)acrylate azeotropes, Published PCT
Application WO 2007/057120 A1 describes a useful entrainer,
Japanese Patent Application 2004/189650 A2 describes a batch
process, and Japanese Patent Application 2004/106278 A1 describes a
batch process which uses water to facilitate the Michael adduct
decomposition.
[0005] Despite all of these attempts however there is still a need
for a simple cost, effective, high yield method of preparing
N,N-dialkylaminoalkyl(meth)acrylates that is a continuous reaction
that allows users to add reagents and catalysts to the ongoing
reaction as desired.
[0006] The art described in this section is not intended to
constitute an admission that any patent, publication or other
information referred to herein is "prior art" with respect to this
invention, unless specifically designated as such. In addition,
this section should not be construed to mean that a search has been
made or that no other pertinent information as defined in 37 C.F.R.
.sctn.1.56(a) exists.
BRIEF SUMMARY OF THE INVENTION
[0007] At least one embodiment is directed towards a method of
preparing a N,N-dialkylaminoalkyl acrylate of Formula 1:
##STR00001##
wherein R.sub.1 is H, or C.sub.1-C.sub.4 alkyl; R.sub.2 is
C.sub.1-C.sub.4 alkylene; and R.sub.3 and R.sub.4 are
C.sub.1-C.sub.4 alkyl. The method comprises: [0008] a) Providing a
distillation reactor comprising a distillation column and a
reboiler. [0009] b) Continuously adding to the distillation column,
entrainer, catalyst, polymerization inhibitor(s), and an alkyl
acrylate of Formula 2
##STR00002##
[0009] wherein R.sub.5 is C.sub.1-C.sub.4 alkyl and a dialkylamino
alcohol is of Formula 3.
##STR00003##
The continuous addition occurs under conditions resulting in the
transesterification of the alkyl acrylate with said dialkylamino
alcohol to form said N,N-dialkylaminoalkyl acrylate and an alcohol
of formula R.sub.5OH. The method also comprises: [0010] c)
Simultaneously removing an azeotropic mixture of the entrainer and
the alcohol from the distillation column and removing the
N,N-dialkylaminoalkyl acrylate and residual reactants from the
reboiler.
[0011] At least one embodiment is directed to a method in which
R.sub.1 is H or methyl, R.sub.2 is ethylene and R.sub.3, R.sub.4
and R.sub.5 are methyl. The entrainer may be selected from the list
consisting of methylpentatne, hexane, heptane, C4-C8 straight chain
hydrocarbons, C4-C8 cyclic hydrocarbons, C4-C8 branched
hydrocarbons, and any combination thereof. The catalyst may be one
item selected from the list consisting of strong acids, strong
bases, tin-based Lewis acids, titanium based Lewis acids, and tin
catalysts that exist as liquids at room temperature and which are
highly soluble in the reaction medium, di-N-butyltin diacetae
(DBTA), and any combination thereof. The entrainer, catalyst,
inhibitor, dialkylamino alcohol and alkyl acrylate may all be added
to the reboiler. The entrainer, catalyst, inhibitor and
dialkylamino alcohol may also be added to the distillation column
and the alkyl acrylate is added to the reboiler. In addition, the
molar feed ratio of methyl acrylate to N,N-dimethylaminoethanol may
be less than or equal to 1.7, and the chemical conversion of
N,N-dimethylaminoethanol to N,N-dimethylaminoethyl acrylate may be
greater than 88%.
[0012] At least one embodiment is directed to a method in which the
distillation column comprises between 1 and 40 distillation trays
arranged sequentially from a bottom of the column to a top of a
column. In addition, one item selected from the list of the
entrainer, the catalyst, and the polymerization inhibitor, and any
combination thereof are fed into the distillation column at a
position lower than a middlemost distillation tray. At least one
embodiment is directed to a method in which there is substantially
no entrainer mixed with the N,N-dialkylaminoalkyl acrylate when the
N,N-dialkylaminoalkyl acrylate is removed from the reboiler.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] A detailed description of the invention is hereafter
described with specific reference being made to the drawings in
which:
[0014] FIG. 1 is an illustration of a process of preparing
N,N-dialkylaminoalkyl acrylate.
DETAILED DESCRIPTION OF THE INVENTION
[0015] "Alkyl" means a monovalent group derived from a straight or
branched chain saturated hydrocarbon by the removal of a single
hydrogen atom. Representative alkyl groups include methyl, ethyl,
n- and iso-propyl, n-, sec-, iso- and tert-butyl, and the like.
[0016] "Alkyl Acrylate" means a composition of matter defining an
alkyl ester of the formula CH2=CHOO-alkyl.
[0017] "Alkylene" means a divalent group derived from a straight or
branched chain saturated hydrocarbon by the removal of two hydrogen
atoms. Representative alkylene include methylene, 1,2-ethylene,
1,1-ethylene, 1,3-propylene, 2,2-dimethylpropylene, and the
like.
[0018] "Continuously Adding" means adding at least one composition
of matter to a continuous reaction.
[0019] "Continuous Reaction" means an ongoing chemical process,
which is capable of continuing over an unlimited period of time in
which reagents can be continuously fed into a reaction operation to
continuously produce product. Continuous Process and Batch Process
are mutually exclusive.
[0020] "Evaporator" means a device constructed and arranged to
convert a pure liquid into a mixture having a high vapor to liquid
ratio in a matter of seconds.
[0021] In at least one embodiment a transesterification reaction is
conducted to produce a N,N-dimethylaminoethyl acrylate (hereinafter
DMAEA) from an alkyl acrylate. The alkyl acrylate may have from 1
to 4 carbons on the alkyl group. In at least one embodiment the
reaction follows Equation I in which methyl acrylate (MA) reacts
with N,N-dimethylaminoethanol (DMAE) to produce
N,N-dimethylaminoethyl acrylate (DMAEA).
##STR00004##
[0022] In at least one embodiment the reaction follows Equation II
in which an ethyl acrylate (EA) reacts with
N,N-dimethylaminoethanol (DMAE) to produce N,N-dimethylaminoethyl
acrylate (DMAEA).
##STR00005##
[0023] Referring now to FIG. 1. there is shown an apparatus in
which the DMAEA product (1) is produced via a transesterification
conducted according to a reactive distillation process. In the
reactive distillation process the transesterification actually
takes place within a single distillation reactor (10). The
apparatus as a whole comprises a reactive distillation section (2),
a purification section (3), and an entrainer recovery section (4).
Reagents, entrainers, and catalysts are added via sources. DMAE is
added to the system via a DMAE source (6). An alkyl acrylate is
added to the system via an alkyl acrylate source (7). One or more
catalysts is fed into the system via one or more catalyst sources
(8). An entrainer is also added to the system via an entrainer
source (5).
[0024] In at least one embodiment the catalyst is one selected from
the list consisting of strong acids (such as sulfuric acid,
p-toluenesulfonic acid), strong bases (such as KOH, NaOH),
tin-based Lewis acids (such as di-N-butyltin oxide, dioctyltin
oxide, di-N-butyltin dioxide, d-N-butyltin diacetate (DBTA),
di-N-butyltin maleate, di-N-butyltin dilaurate, and di-N-butyltin
dimethoxide, as well as other dialkyl tin oxides, tin carboxylates,
tin alkoxides, di-alkyl stannanes, di-aryl stannanes, tri-alkyl
stannanes, tri-aryl stannanes, distannoxanes, and tin (IV)
chloride), titanium based Lewis acids (such as (tetraethyltitanate)
tetraisopropyl titanate, tertbutyl titanate,
tetra(N,N-dimethylaminoethoxy)titanate, alkoxytitanates, and tin
catalysts that exist as liquids at room temperature and which are
highly soluble in the reaction medium), and any combination
thereof.
[0025] The entrainer azeotropically removes alcohol co-products
formed during the transesterification reaction. In at least one
embodiment the entrainer is a liquid. In at least one embodiment
the entrainer is one selected from the list consisting of
methylpentatnes, hexane, heptane, C4-C8 straight chain
hydrocarbons, C4-C8 cyclic hydrocarbons, C4-C8 branched
hydrocarbons, and any combination thereof.
[0026] The reagents and catalysts are fed to a distillation reactor
(10). In at least one embodiment the distillation reactor (10)
comprises a distillation column, a reboiler (19), and a condenser
(12). In at least one embodiment, the reboiler (19) is a kettle
reboiler. Both the reboiler (19) and condenser (12) are in fluidic
communication with the distillation column. In at least one
embodiment at least a portion of the reboiler (19) is beneath at
least a portion of the distillation column.
[0027] In at least one embodiment there are from 1 to 60
distillation trays are positioned in vertical sequence along the
distillation column. In at least one embodiment some or all of the
catalyst, DMAE, and/or entrainer are added to the same tray within
the distillation reactor (10). In at least one embodiment the
catalyst, DMAE and entrainer are fed to the distillation reactor
(10) via a single port (11). In at least one embodiment, at least
one of the catalyst, DMAE, and entrainer are fed to a tray located
between the first and the 20th tray counting from the bottom tray
of the distillation column (10). In at least one embodiment the
distillation bottoms (21), which includes alkyl acrylate is fed
into the reboiler (19). In at least one embodiment the respective
feed rates of entrainer, DMAE, catalyst, and alkyl acrylate are set
to a ratio of 0.935/1.00/0.030/1.451.
[0028] In at least one embodiment, the entrainer forms a volatile
azeotrope distillation. In a volatile azeotrope distillation, the
alcohol co-product forms an azeotrope with the entrainer, which
forms a distinct distillation fraction. This azeotrope is more
volatile than the other materials within the column and as a result
this azeotrope has the strongest tendency to travel up the column.
As a result alcohol with entrainer are substantially the only items
that move upwards to the top of the distillation column under
certain conditions.
[0029] This volatile azeotrope distillation is substantially
different from the prior art uses of entrainers in continuous
esterification processes. For example, WO 2007/057120 A1 describes
an extractive distillation method. In an extractive distillation,
the entrainer is not a part of a volatile azeotrope with alcohol.
As a result, the alcohol travels up the column without the
entrainer accompanying it. This is because the entrainer is instead
kept in contact with the MA and is used to suppress the volatility
of the MA and thereby prevent its forming of an azeotrope with the
alcohol co-products.
[0030] The inventive volatile azeotrope method is accomplished by
using different methodologies and chemicals than are used in
extractive distillation. Extractive distillation makes use of
volatility suppressing entrainers such as dibenzyl ether,
diethylene glycol dibutyl ether, diethylene glycol di-n-butyl
ether, triethylene glycol dibutyl ether, diethylene glycol diethyl
ether, and tripropylene glycol dimethyl ether. In contrast, the
inventive volatile azeotrope method makes use of at least one
azeotrope forming entrainer, which does not suppress volatility.
The thermodynamic differences between these two methods result in
far less entrainer and catalyst needed per unit of alkyl acrylate.
In addition, the bottoms product (13) is not contaminated with
large amounts of entrainer.
[0031] Because the entire transesterification reaction is occurring
within a single distillation reactor (10), the reaction may be
conducted under continuous reaction conditions. As a continuous
reaction, additional amounts of entrainer, DMAE, catalyst, and
alkyl acrylate may be added continuously to create more DMAEA
product without waiting for a first batch to complete its reaction.
Furthermore the addition rates of entrainer, DMAE, catalyst, and/or
alkyl acrylate, are varied in order to fine-tune the reaction while
it is still running.
[0032] In addition, by conducting the transesterification reaction
in a single distillation reactor (10) the process is highly
efficient and can be performed using lower amounts of alkyl
acrylate and entrainer relative to the amount of DMAE than is
feasible using prior art methods. Lastly because the reaction
occurs in a single distillation reactor, it allows for simultaneous
removal of alcohol co-products and addition of more reagents and/or
catalysts which makes the reaction conversion highly favorable. In
at least one embodiment a high conversion is achieved even with a
low ratio of alcyl acrylate to DMAE of less than 1.5. In at least
one embodiment a high conversion is achieved even with a low amount
of catalyst (<2.5 weight percent of DMAE). In at least one
embodiment, the temperature of the bottom stream of the
distillation reactor (10) distillation column is between
190.degree. F. and 205.degree. F.
[0033] In the purification section (3), the bottoms product (13) of
the distillation reactor (10) is fed to a purification distillation
column (20) equipped with a heat exchanger (15). The bottoms
product (13) are the crude product of the distillation reactor (10)
and are fed to the purification distillation column (20), which
separates out excess and unreacted raw materials (14) for recycling
and feeds them back to the distillation reactor (10). The recycled
materials (14) include alkyl acrylates and
N,N-dimethylaminoethanol. The bottoms of the purification
distillation column (20) contains crude DMAEA.
[0034] The distilled bottoms of the purification distillation
column (20) pass on to a final distillation column (23). The final
distillation column (23) is in fluidic communication with an
evaporator (9). The evaporator (9) separates the catalysts and
heavy co-products from the DMAEA product and functions as a
reboiler for the final distillation column (23). Purified DMAEA
product (1) is collected as the distillate from the final
distillation column (23). At least some of the bottoms (16) of the
evaporator (9) which may comprise DMAEA, catalyst, and high boiling
point impurities are recycled back to the distillation reactor
(10). In at least one embodiment, the DMAEA product (1) is
stabilized with a free-radical polymerization inhibitor (24) such
as the methyl ether of hydroquinone (MEHQ).
[0035] The entrainer recovery section (4) receives the distillate
(17) from the condenser (12). A separation apparatus (18) is used
to separate the alcohol co-product from the entrainer (22). The
invention encompasses any and all of the many methods of recovering
entrainer known in the art. In at least one embodiment the
separation apparatus (18) also removes recycled water and
salts.
[0036] In at least one embodiment, the feed mole ratio of alkyl
acrylate to DMAEA is 1.1 to 2.0. In at least one embodiment, the
temperature within the reboiler (19) is between 85 C and 120 C
preferably <100 C and most preferably <95 C. In at least one
embodiment, the weight percentage of catalyst relative to DMAE is
<5% and preferably <3%.
[0037] The foregoing may be better understood by reference to the
following examples, which are presented for purposes of
illustration and are not intended to limit the scope of the
invention.
EXAMPLE 1
Preparation of N,N-Dimethylaminoethyl acrylate by Reactive
Distillation
[0038] A stainless steel pilot scale reactive distillation unit was
employed for this example. It consisted of a distillation column of
15.4 cm internal diameter with 35 sieve trays spaced 15.2 cm apart.
The associated components included a condenser and accumulator to
condense and return a portion of the overhead condensate, and a
kettle reboiler of standard configuration to supply heat to the
unit. A solution comprised of 51 parts DMAE reactant, 47.5 parts
hexane entrainer, and 1.5 parts DBTA catalyst was added
continuously at a rate of about 10.5 pounds per hour to the fifth
plate from the bottom of the distillation column. Simultaneously,
methyl acrylate (MA) reactant was added at a rate of about 7.75
pounds per hour to the reboiler, representing an MA/DMAE molar feed
ratio of 1.5:1. The methanol co-product was removed from the
distillation column and condensed in a heat exchanger as a
hexane/methanol azeotrope. The distillate was collected from the
top of the column at a rate of about 7.4 pounds per hour, and at a
column head pressure of about 14.2 psia. The DMAEA product was
removed from the system, along with any unreacted MA and DMAE, from
the bottom of the system. The bottoms were withdrawn from the
reboiler at a rate of about 11.0 pounds per hour. The temperature
of the contents of the reboiler were about 92 degrees Celsius.
[0039] The distillate was comprised primarily of hexane and
methanol, containing less than two weight percent methyl acrylate
impurity. About ninety five percent of the condensed distillate was
returned to the column (reflux ratio=20). A methanolic solution of
4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy free radical inhibitor
was added to the condensed distillate in an amount sufficient to
provide 100 ppm inhibitor concentration in the condensed distillate
returned to the distillation column in order to help prevent
polymerization in the column.
[0040] The bottoms withdrawn from the reboiler primarily comprised
the desired DMAEA product and the excess MA that was added to the
reactor. In addition, the bottoms were contaminated with percent
levels of unreacted DMAE and catalyst, along with smaller amounts
of methanol, hexane, and heavy impurities. The GC analyses of the
bottoms, which represent the crude product of the reactive
distillation process, are shown in table 1. In this example, a 94
mole percent conversion of DMAE to DMAEA was achieved under mild
reaction conditions that produced very low levels of heavy volatile
impurities.
EXAMPLES 2-7
Preparation of N,N-Dimethylaminoethyl acrylate by Reactive
Distillation
[0041] DMAEA was produced as described above in Example 1, except
that the process conditions were varied as described in the table
below. The process variables included the MA/DMAE molar feed ratio
(MA/DMAE), the weight percent catalyst based on the total weight of
DMAE reactant (wt. % Cat), the percent reaction conversion of DMAE
to DMAEA (% Conv.) based on the GC analysis described below, the
bottoms temperature (T.sub.B (.degree. C.)), and the residence time
in the reboiler expressed in hours (Res. Time (h)). In general, a
high chemical conversion of the limiting DMAE reactant to the
desired DMAEA product could be achieved under desirable process
conditions (low MA/DMAE feed ratios, a low amount of catalyst, and
a low reboiler temperature (<100 C)). The volatile components of
bottoms samples representative of the experimental process
conditions are measured by gas chromatography (GC) and the results
are listed under the "Volatile Components" heading in the table.
The bottoms compositions from examples 1 and 2 illustrate the
achievement of a high DMAEA concentration (>60 wt. %), a high
DMAE conversion (>85 mole %), and a low impurity level (<1
wt. %) in the bottoms. The results from examples 5 and 7 confirm
that high DMAE conversions (>90%) and low levels of byproduct
(<1%) can be achieved with relatively low MA/DMAE feed ratios of
1.6 (Example 6) or 1.7 (Example 7). Example 3 illustrates that the
MA/DMAE feed ratio can be desirably reduced even further (down to
1.2 in Example 3), but the reboiler temperature will increase to
greater than 100 C in this case, and this will result in a higher
level of impurities Examples 4 and 6 illustrate that if the
reboiler residence time is reduced to about 2 hours, the chemical
conversion of DMAE to DMAEA will suffer.
TABLE-US-00001 TABLE 1 Process Conditions MA/ wt % TB Res. Volatile
Components (wt %) Example DMAE Cat % Conv. (.degree. C.) Time (h)
DMAEA MA DMAE MeOH Hexane Impurities 1 1.5 3 94 92 4.5 69.5 24.7
2.9 0.27 2.6 0 2 1.5 2 88 91 5 68.1 22.2 5.8 0.28 3.2 0.42 3 1.2 2
93 102 5 79.2 15.2 3.5 0.17 1.0 1.02 4 1.2 4 75 68 2.3 59.4 23.8
12.0 0.51 4.2 0.2 5 1.6 4 91 87 3.9 57.8 35.9 2.8 0.23 3.2 0.14 6
1.6 4 72 82 1.8 50.4 30.1 12.1 0.38 6.9 0.13 7 1.7 4 91 85 3.7 57.8
34.3 3.6 0.27 4.0 0
[0042] While this invention may be embodied in many different
forms, there are shown in the drawings and described in detail
herein specific preferred embodiments of the invention. The present
disclosure is an exemplification of the principles of the invention
and is not intended to limit the invention to the particular
embodiments illustrated. Furthermore, the invention encompasses any
and all possible combinations of some or all of the various
embodiments described herein. Any and all patents, patent
applications, scientific papers, and other references cited in this
application are hereby incorporated by reference in their
entirety.
[0043] The above disclosure is intended to be illustrative and not
exhaustive. This description will suggest many variations and
alternatives to one of ordinary skill in this art. All these
alternatives and variations are intended to be included within the
scope of the claims where the term "comprising" means "including,
but not limited to". Those familiar with the art may recognize
other equivalents to the specific embodiments described herein
which equivalents are also intended to be encompassed by the
claims.
[0044] This completes the description of the preferred and
alternate embodiments of the invention. Those skilled in the art
may recognize other equivalents to the specific embodiment
described herein which equivalents are intended to be encompassed
by the claims attached hereto.
* * * * *