Note: Descriptions are shown in the official language in which they were submitted.
~z~
In the present invention, there is provided a process for preparing
N-ethylethylenediamine
H
C2H5~CH2CH2NH2
(hereafter referred to as NEED) wherein an ethyl halide is reacted with
ethylenediamine (hereafter referred to as EDA) at a temperature of from about
-10C to about 120C. and at a mole ratio of EDA to said ethyl halide of
about 1-20:1, in the presence of about 0-50% by weight of water, to form
a reaction mixture containing NEED. The resulting reaction rmxture is then
contacted with an aqueous alkalizing agent to form a liquid two-phase mixture
consisting of an organic layer and an aIkalized aqueous layer and the alkaliz-
ed aqueous layer is separated. The organic layer is diluted with about 0.2-
100% by weight of a suitable aliphatic hydrocarbon solvent and the resulting
mlxture is azeotropically fractionally distilled to remove all the water
and unreacted EDA therefrom. The resulting reaction mixture is then
fractionally distilled to remove residual hydrocarbon solvent and recover
NEED in a purity greater than about 99%.
In one aspect, the present invention provides a process for prepar-
ing N-ethylethylenediamine (NEED) comprising reacting ethylenediamine (EDA)
and an bth~l halide at a mole ratio of EDA to said ethyl halide of about
1-20:1 and a tem~erature of from about -lo&. to about 120C in the presence
of about 0-50% by wei~ht of water to obtain an aIkylation reaction mixture;
neutralizing said reaction mixture by contacting with an aqueous solution
containing about 1 - 2 molecular equivalents of an inorganic aIkalizing
agent based on the ethyl halide; separating the aqueous layer ~rom the
neutralized organic layer and adding to said organic layer about 0.2-100%
by weight, based on the weight of said organic layer, of a suitable aliphatic
hydrocarbon solvent selected from the group consisting of n-heptane, iso-
octane, cyclohexane, n-hexane, methylcyclohexane, and _-pentane; azeotropical-
ly fractionally distilling all water and EDA from the resulting mixture;
and fractionally distilling the resulting reaction mixture to remove
residual hydrocarbon solvent and recover NEED in a purity greater than about
- 2 -
.,j ~ .
. ~
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99% .
Preferably the reaction between the ethyl halide and the EDA
is carried out at about 25 - 50C in the presence of about 15 - 30% by
weight of water and at a mole ratio of ED~ to ethyl halide of about 2-5:1.
me resulting reaction mixture is then contacted with aqueous caustic soda
and the organic layer is diluted with about 0.2-20% by weight of the ali-
phatic hydrocarbon solvent before carrying out the distillation.
The process of the subject invention can be mcdified by the
addi.tional steps of: (1) recovering and recycling aqueous EDA from the
azeotroper (2) recovering and recycling the aliphatic hydrocarbon solvent,
and (3) contacting the separated, alkalized aqueous layer with about 10 -
100% by weight of said hydrocarbon
- 2a -
~L~Z~
solvent based on the weight of said organic layer, separating the
extracted aqueous layer and diluting the organic layer with the
hydrocarbon extract before proceeding with the azeotropic frac-
tional distillation.
The present invention also provides processes for the
removal of water and/or EDA from NEED by addiny a suitable ali-
phatic hydrocarbon solvent thereto, azeotropically fractionally
distilling the water and/or EDA therefrom, and fractionally dis-
tilling to remove residual hydrocarbon solvent and recover anhy-
drous and/or ~DA-free, NEED. The advantages of the process of
the present invention over previously available processes are that
(1) the final product ha~ a purity greater than about 99%; and
(2~ the process results in high yields and high productivity~
In accordance with the present invention there is also
provided an alternative process for preparing NEED of about 99~
purity comprising (a) reacting an ethyl halid~ and EDA at a mole
ratio of EDA to said ethyl halide of about 1-20:1, and a tempera-
ure of about -10C to about 120C under anhydrous conditions to
obtain an alkylation reaction mixture; (b) adding thereto about
- 20 0~2-30% by weight of a suitable aliphatic hydrocarbon solvent,
based on the weight of said alkylation reaction mixture; (c) frac-
tionally distllling a mixture of EDA and said aliphatic hydrocarbon
solvent therefrom to essentially remove EDA from the resulting mix-
ture; (d) neutralizing the resulting reaction mixture by contact-
ing it with at least 0.9 molecular equivalent of a suitable alka-
lizing agent per mole of said ethyl halide to form a slurry of an
alkali halide precipitate; (e) separating said alkali halide from -
said slurry and recovering the resulting mother liquor therefrom;
' (f),,washing said separated alkali halide with said aliphatic hydro-
carbon solvent; (g) fractionally distilling a combination of said
mother liquor from step (e) plus recovered aliphatic hydrocarbon
S9
wash liquor from step (f) to remove essentially all water and re-
sidual EDA from the resulting mixture; and (h) fractionally dis-
tilling ~he resulting reaction mixture to remove residual ali-
phatic hydrocarbon solvent and recover said NEED.
EDA, either as an anhydrous liquid or containing water,
and an ethyl halide, preferably ethyl chloride, are admix~d in a
suitable reactor vessel while agitating and maintaining the reac-
tion mixture at from about -10C to about 120C. (preferably at
about 25-50C), over a period of about 5-15 hours (preferably
about 7-9 hours) t to provide a mole ratio of EDA to ethyl halide
of about 1-20:1 (preferably about 2-5:1) and form a reaction mix-
ture containing about 0-50% by weight of water (preferably about
15-30%). Suitable ethyl halides include ethyl chloride, ethyl
bromide and ethyl iodide. The total residence time in the reactor
vessel depends on the temperature employed, with shorter residence
times employed with higher temperatures.
The reaction mixture is then vi~orously contacted with
an aqueous solution of an alkalizing agent to form a two-phase
liquid mixture, consisting of an organic layer and an alkalized
aq~eous layer. Sufficient alkalizing agent is employed so $hat
the p~ of the aqueous layer does not go below about 7, preferably
not below 8. Suitable alkalizing agents include sodium and pot-
assium hydroxide, either singly or in mixtures. The preferred
alkalizing agent is about 50% aqueous sodium hydroxide.
After allowing the two-phaæe mixture to settle, the
aqueous layer is separdt~d therefrom to obtain an organic layer
containing NEED, unreacted EDA, and higher alkylation products
such as N,N'-diethylethylenediamine, N,N-diethylethylenediamine,
N,N,N'-triethylethylenediamine, and N,N,NI,N'tetraethylethylenedi-
amine. The aqueous layer generally contains about 1-3~ EDA and
about 0.5-1% NEED. The organic layer is then diluted with about
-- 4 --
:,,
10-100% by weight, preferably about 10-20% by weight, of a suit-
able aliphatic hydrocarbon solvent, based on the ~7eight of said
organic layer.
Preferably, the separated aqueous layer is extracted
with about 10-100~ by weight, preferably about 10-20% by
weight, oE said suitable aliphatic hydrocarbon solvent, based
on the weight of said organic layer and the two-phase mixture
is allowed to settle. The extracted aqueous layer is then sepa-
rated and the hydrocarbon solvent extract is used to dilute the
above mentioned organic layer.
As employed herein, the term "suitable aliphatic hydro-
carbon solvent" is defined as an aliphatic hydrocarbon solvent
which is miscible with NEED, immi~cible with EDA, and which azeo-
tropes with water and/or EDA below about 128~C. to about 131C.
without inclusion of substantial amounts of NEED. Suitable ali-
phatic hydrocarbon solvents include n-heptane, sooctane/ cyclo-
hexane, n-hexane, methylcyclohexanel n-pentane, and the like, al-
though the preferred aliphatic hydrocarbon solvent is n-heptane.
Aromatic hydrocarbons cannot be used instead of aliphatic hydro-
carbons because they are miscible with both EDA and NEED.
The diluted organic layer is then heated to boiling
through a distillation column to azeotropically fractionally dis-
till off any residual EDA and water. After allowing the distil-
late to settle, the lower EDA-water layer may be separated and
recycled to the alkylation vessel, and the upper hydrocarbon layer
may be recycled to the distillation vessel until anhydrous EDA-
free NEED is obtained, or transferred to a vessel for extraction
of the original two-phase mixture.
The residual EDA-free reaction mixture, containing
NEED, higher alkylated ethylenediamines, and the aliphatic
-- 5 --
s~
\~
hydrocarbon solvent is now fractionally distilled, using a
fractionation column containing sufficient theoretical plates,
to separate said aliphatic hydrocarbon solvent from NEED. -
For example, using a column containing 15 theoretical plates
and n-heptane as the solvent, the n-heptane distills off as a
forerun boilingat about 98-100C. The forerun of hydrocarbon
solvent so obt~ined may be recycled to other stagesof the
process, such as dilution of the organic layer, azeotroping,
EDA and water from the reaction mixture, or extracting the
aqueous layer, as described above.
After removal of the Eorerun of hydrocarbon solvent,
the distillation ls continued to obtain NEED (b.p. 130-131C,
purity greater than 99%) in a yield of about 63-65~ based on
the ethyl halide charged. The procedure employed herein may
also be used to remove water and/or EDA from NEED by adding
a suitable amount of said hydrocarbon solvent thereto, azeo-
tropically frac~ionally distilling water or EDA, or both, therefrom
and fractionally distilling the residue to remove excess hydro-
carbon solvent and obtain anhydrous, EDA-free NEED. It is
to be understood that the aforedescribed process may also
be carried out continuously using appropriate vessels,
such as cantinuous flow reactors, splitter vessels, distil-
lation columns, and the like.
In the alternative pro oess ethylediamine as an anhy-
drous liquid, is reacted with an ethyl halide as shown belcw
H
C2H5X ~ H2N-VH2CH2-NH2-----------~ C2H5 C 2 2 2
wherein X is a halo atom, such as chloro, bro~o, fluoro, or ido,
preferably chloro. The reaction is carried out while agitating
the reaction mixture in a suitable reactor vessel at about -10C
~ZO~)~9
to about 120C, preferably at about ~5-75C, over a period of
about 1-24 hours, preferably about 2-6 hours. The mole ratio of
EDA to ethyl halide employed is about 1-20 to 1, preferably about
2-5 to 1. The total residence time in the reactor vessel will de-
pend on the temperature employed, with shorter residence times em-
ployed with higher temperatures.
Upon completion of the reaction, the reaction mixture
is diluted with about 0.2-30% by weight, preferably about 0.5-
1.0~ by weight, of a suitable aliphatic hydrocarbon solvent, based
on the weight of the reaction mixture. As employed herein the
term "suitable aliphatic hydrocarbon solvent" has the same mean-
i~g as previously defined. The diluted reaction mixture is then
heated to boiling through a distillation column to azeotropically
fractionally distill of~ any residual EDA. Optionally, the EDA
distilla~e may be reco~ered and recycled.
~ ~ Suitable aliphatic hydrocarbon solvents include n-heptane
isooctane, cyclohexane, n-hexane, methylcyclohexane, n-pentane,
and the like, although the preferred aliphatic hydrocarbon sol-
vent is n-heptane.
The reaction mixture is then neutralized by contacting
it with at least 0.9 molecular equivalent of a suitable alkali-
zing agent per mole of alkyl halide us~d. As employed herein the
term "suitable alkalizing agent" is defined as sodium or potas-
sium hydroxide, either singly or in mixtures. The pre~erred al~a-
~5 lizing agent is 50% aqueous sodium hydroxide.
The resulting alkali halide precipitate is sep~rated
from the resulting slurry by conventional means, such as filtra-
tion or centrifugation, and washed with the aliphatic hydrocarbon
solvent described previously, preferably with n-heptane.
The aliphatic hydrocarbon solvent wash liquors are col-
-- 7 --
~LlZ0~5~9
lected and combined with the mother liquor obtained by the sepa-
ration of the alkali halide precipitate from the slurry formed
by the addition of an alkalizing agent to the reaction mixture.
The eombined liquors are azeotropically fractionally distilled
at atmospheric pressure through a packed column, preferably with
recycle of heptane distillate to the top of the column, until
the residual material is essential]y free of EDA and water.
The resulting essentially EDA-free reaction mixture,
eontaining the produet NEED, higher alkylated ethylenediamines,
and the aliphatic hydrocarbon solvent is now fractionally distil-
led, using a fractionation column containing sufficient theoret-
ical plates, to separate said aliphatic hydrocarbon solvent from
the product NEED. For example, using a column containing 15 theo-
retical plates, n-heptane distills off as a forerun boiling
at about 98-100C. The forerun of hydrocarbon solvent so ob-
tained may be reeycled to other stages of the process, such as
dilution of the reaction mixture, or azeotroping ED~ or water from
the reaction mixture.
After removal o~ the forerun of hydrocarbon solvent
the reaction mixture is preferably clarified to remove any insol-
ubles and distillation of the clarified solution is continued to
obtain NEED (b.p. 130-131C) in a purity greater than 99% and a
yield of about 62-65% of theoretical based on the ethyl halide
charged.
It is to be understood that the aforedescribed process
may also be earried out continuously using appropriate vessels,
sueh as continuous flow reactors, separation vessels, distilla-
tion columns, and the like.
The following examples are provided to illustrate
0 the invention. Except as otherwise noted, all parts are by
-- 8 --
- ~,'h~
weight and all ranges are inclusive of both numbers. The purity
of the product is expressed as area percent, as determined by
vapor phase chromatography (VPC).
Example 1
This example illustrates the use of anhydrous EDA.
Ethyl chloride (565 grams; 8.76 moles) is added to an-
hydrous EDA (1420 grams; 23.63 moles) at 30-40C over a period
of 5 hours. The reaction mixture is stirred for 2 hours after
the addition is completed and 50% caustic soda (935 ml; 17.5
moles) is added thereto. The resulting two-phase mixture is stir-
red for 30 minutes, allowed to settle, and the aqueous phase is
separated and extracted twice with 150 ml. of n-heptane. The hep-
tane extracts are added to the organic phase and the combined
solution is heated to azeotropically distill water and EDA there-
from at 33-97C., using a fractionation column and a splitter
device to return distilled heptane to the distillation vessel and
to separate the denser aqueous EDA phase. In this ~anner an
aqueous EDA phase is separated consisting of 394 grams of water
and 896 grams of EDA (14.91 moles). The EDA~free residue is
fractionally distilled to obtain a heptane forerun (b.p. 98~-102C.)
containing 3-4% by weight of NEED, and 484 grams of NEED ~b.p.
130-131C.) of greater than 99.8% purity by VPC~ The yield is
62.7~ of theoretical based on ethyl chloride.
Example 2
This_example illustrates the_u~e of recovered aqueous EDA
Ethyl chloride (545 grams; 8.45 moles) is added at 30-
40C. over a period of 5 hours to a mixture of 1245 grams of aque-
ous eda recovered from Example 1 (containing 14.39 moles of EDA)
and anhydrous EDA (555 grams; 9,23 moles). The reaction mixture
is stirred or 2 hours after the addition is completed and 50~
_ g _
~ ~'Z O ~ 3 9
caustic soda (902 ml; 16.9 moles) is added thereto. The resulting
two-phase mixture is processed as described in Example 1 utilizing
recovered n-heptane from Example 1 to extract the separated aque-
ous phase. Fractional distillation of the EDA-free residual
material yields a heptane forerun containing 3-4% by weight of
NEED, and 483 grams of NEED (b.p. 130-131C) of greater than
99.8~ purit~ by VPC. The yield is 65% of theoretical based on
ethyl chloride.
EX~MPLE 3
This example illustrates the separation of EDA from
NEED by azeotropic distillation.
A mixture of EDA (500 grams) and NEED (500 grams) is
diluted with 200 ml. of n-heptane and heated to azeotropically
fractionally distill (b.p. 87-90C) EDA therefrom, using a dis-
tillation column and a device which returns -the recovered heptane
to the distillation apparatus and allows for the recovery of the
denser EDA phase. The EDA thus recovered contains less than 1%
ME$D by VPC. The EDA-free residue is then fractionally distil- ~;
led to recover a heptane forerun and pure NEED (b.p. 130 131 C).
In the manner described above, substituting cyclo-
hexane, _-hexane, or isooctane for the n-heptane, similar resul-
ts are obtained.
EXAMPLE _
This example illustrates the separation of water
for NEED by azeotropic distillation.
To a mixture of 56 grams of NEED and 10 grams of
water is added 50 ml. of n-heptane. The mixture is heated to
boiling and the water is azeotropically fractionated (b.p. 88-
98&) therefrom using a distillation column and a splitter appa~
ratus which returns the recovered heptane to the distillation
-- 10 --
'~"' `` ''
r~9
apparatus and allows for the removal of the denser water phase.
After removal of the water is complete, the residue is fractionally
distilled to recover a heptane ~orerun and NEED (b.p. 130-131~C)
containing less than 0.2% water by VPC.
In the manner described above, substituting cyclo-
hexane, n-hexane, or lsooctane for the n-heptane, similar
results are obtained.
EXAMPLE 5
Ethyl chloride t62.4 grams; 0.967 mole) ls added to
stirred ethylenediamine (146.3 grams; 2.43 moles) over a period
of 1 hour while allowing the temperature to rise to 95C. Upon
completion of the addition of the ethyl chloride, n-heptane (34.2
grams) is added thereto and the resulting mixture is azeotropical-
ly distilled using a fractionatlon column and a Dean-Stark device
to collect the two-phase liquid distillate consisting of a lower
layer of ethylenediamine (85.09 grams) and an upper layer of hep-
tane which is recycled back to the fractionation column until all
of the ethylenediamine is removed therefrom.
The remaining material is cooled to 80~C, neutralized
with 50% aqueous sodium hydroxide (77.36 grams; 0O967 mole) and
the resulting precipitate of sodium chloride is separated by fil-
tration to obtain a filter cake and a two-phase liquid filtrate.
The filter cake is then washed with heptane (50 mls) and the wash-
ing is added to the original two-phase filtrate.
The resulting two-phase liquid is then azeotropically
distilled using a fractionation column and a Dean-Stark device to
collect the two-phase distillate consisting of n heptane and water.
After all of the water is removed the residue is fractionally
distilled to remove any heptane and recover N-ethylethylenediamine
(54.5 grams; b.p. 130-131~C, 64% of theoretical) in a purity of 99%.
-- 11 --
EX~MPLE 6
The procedure of Example S is followed in every detail
up to the point of the final distillation. After all the water
is removed by azeotropic distillation the residual material
is filtered to separate a white precipitate (4.32 grams). The
filtex cake is then washed with heptane (16 gxams) and the wash-
ing is combined with the filtrate. The combined filtrate plus
washing is then fractionally distilled to remove heptane and re-
cover N-ethylethylenediamine (53.7 grams; b.p. 130-131~C; 63% of
theoretical) in 99% purity.
EXAMPLE 7
To a glass-lined reactor is charged 848 parts of ethyl-
enediamine (98%) followed by 331 parts of liquid ethyl chloride,
charged through a dip leg at a rate to maintain the reaction
lS mixture at 45-55C. The mixture is stirred for 2 hours and 91
parts of heptane are added thereto. The excess ethylenediamine
is azeotropically distilled off through a packed column with re-
cycle of the heptane distillate to the top of the column. A tot-
al of 492 parts of ethylenediamine is recovered from the distil-
late for recycle. The reaction mixture is neutralized with 402
parts of 50% caustic soda, cooled to room temperature, and cen-
trifuged to remove the sodium chloride by-product. The salt cake
is washed with 70 parts of heptane and the wash liquor is combined
with the mother liquor in a glass-lined vessel. Water is azeo-
tropically distilled off from the combined liquors through a pack-
ed column with recycle of the distilled heptane to thP top of the
column. After all of the water is removed the heptane is fxac-
tionally distilled off through the packed column to obtain a resi-
due containing 273 parts of N-ethylethylenediamine. This residue
is reserved for subsequent combination with the residues of Ex-
- 12 -
)Q~9
amples 8-10.
EXAMPLE 8
-
To a glass-lined reactor is charged 492 parts of re-
covered ethylenediamine from Example 7 and 375 parts of fresh
ethylenediamine (98%). To this mixture is charged 331 parts of
ethyl chloride at a rate to maintain the reaction mixture at 55-
65C. The mixture is stirred for 2 hours and 45 parts of recov-
ered heptane from Example 7 are added thereto. The excess ethyl-
enediamine is azeotropically distilled off through a packed col~
umn with recycle of the heptane distillate to the top of the
column. A total of 501 parts of ethylenediamine is recovered
from the distillate for recycle. The reaction mixture is neutra-
lized with 407 parts of 50% caustic soda, cooled to room tempera-
ture, and centrifuged to remove the sodi~ chloride by-product.
The salt cake is washed with 78 parts of heptane and the wash
liquor is combined with the mother liquor in a glass-lined ves-
sel. Water i5 azeotropically distilled off from the combined
liquors through a packed column with recycle of the distilled
heptane to the top of the column. After all of the water is re-
moved the heptane is fractionally distilled off through the pack-
ed column to obtain a residue containing 288 parts of N-ethyleth-
ylenediamine. This residue is xeserved for subsequent combination
with the residues of Examples 7, 9 and 10.
EXAMPLE 9
To a glass-lined reactor is charged 501 parts of recov-
ered ethylenediamine from Example 8 and 396 parts of fresh ethyl-
enediamine (98%). To this mixture is charged 331 parts of ethyl
chloride at a rate to maintain the reaction mixture at 65-75C.
The mixture is stirred fo~ 2 hours and 28 parts of recovered hep-
tane from Example 8 are added thereto. The excess ethylenediamine
- 13 -
z~
is azeotropically distilled off through a packed column with re-
cycle of the heptane distillate to the top of the column. A tot-
al of 504 parts of ethylenediamine is recovered from the distil-
late for recycle. The reaction mixture is neutralized with 409
parts of 50% caustic soda, cooled to room temperature, and centri-
fuged to remove the sodium chloride by-product. The salt cake is
washed with 82 parts of heptane and the wash liquor is combined
~ith the mother liquor in a glass-lined vessel. Water is azeo-
tropically distilled off from the combined liquors through a pack-
ed column with recycle of the distilled heptane to the top of thecolumn. After all of the water is removed the heptane is frac-
tionally distilled off through the packed column to obtain a re-
sidue containing 310 parts of N-ethylethylenediamine. This resi-
due is reserved for subsequent combination with the residues of
Examples 7, 8 and 10.
EXA~PLE 10
To a glass-lined reactor is char~ed 504 parts of re-
covered ethylenediamine from Example 9 and 388 parts of fresh
ethylenediamine (98%). To this mixture is charged 331 parts o
ethyl chloride at a rate to maintain the reaction mixture at 55-
- 65C. The mixture is stirred for 2 hours and 30 parts of recov-
ered heptane from E~ample 9 are added the~eto. The e~cess eth-
ylenediamine is azeotropically distilled off through a packed
column with recycle of the heptane distillate to the top of
the colum~. A total of 523 parts of ethylenediamine is recover-
ed from the distillate for recycle. The reaction mixture is
neutralized with 409 parts of 50~ caustic soda, cooled to room
temperature, and centrifuged to remo~e the sodium chloride b~-
product. The salt cake is washed with 91 parts of heptanP and
~he wash liquor is combined with the mother liquor in a glass-lined
~ ~Z~05~
vessel. Water is azeotropically dis~illed off from the combined
liquors through a packed column with recycle of the distilled
heptane to the top of the column. After all of the water is re-
moved the heptane is fractionally distilled off through the packed
column to obtain a residue containing 317 parts of N-ethylethyl-
enediamine which is combined with the residues of Examples 7, 8
and 9. The resulting material is fractionally distilled through
a packed column at atmospheric pressure to obtain 1120 parts of
N-ethylethylenediamine, b.p. 129-131C. The yield is 61.9% of
theoretical based on ethyl chloride.
- 15 -
