Process for the preparation of 3-hydroxypropanal

Details Process for the preparation of 3-hydroxypropanal Process for the preparation of 3-hydroxypropanal

1999-08-25

2001-09-04

Padmanabhan, Sreeni (Department: 1621)

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

Organic compounds

Oxygen containing

C568S458000, C568S862000, C568S895000

Reexamination Certificate

active

06284930

ABSTRACT:

FIELD OF THE INVENTION
The invention concerns a process for the preparation of 3-hydroxypropanal.
TECHNICAL BACKGROUND
3-Hydroxypropanal is an intermediate product in the preparation of 1,3-propane diol. 1,3-Propane diol may be further processed to form polyesters, for example poly(trimethylene terephthalate), which is useful for the spinning of fibers, or may be processed to other articles of commerce such as polyols.
It is known that 3-hydroxypropionaldehyde (3-hydroxypropanal) can be prepared by hydration of acrolein with water in the presence of a chelate-forming ion exchanger at temperatures of 30 to 120° C. and pressures of 1 to 20 bars as described in U.S. Pat. No. 5,171,898, herein incorporated by reference.
U.S. Pat. No. 5,284,979 discloses the hydration of 2-alkenals to 3-hydroxyalkanals in a homogeneous phase in the presence of an acid catalyst and a dissolved acid-base buffer which results in a pH of from 2 to 5. A preferred acid base buffer is propanoic acid/triethyl ammonium propionate.
EP 0713853 discloses the addition of oxalic acid to a process for the hydration of acrolein to 3-hydroxypropanal in the presence of a lead-containing ion exchange resin.
Japanese Patent application Kokai No. H 8-143502 discloses the preparation of 3-hydroxyalkanals by the hydration of unsaturated aldehydes in the presence of a metal-carrying ion-exchange resin with the addition of a carboxylic acid to the reaction mixture. Mono and polycarboxylic acids are broadly disclosed, a dicarboxylic acid such as oxalic acid is especially preferred.
The known processes have the disadvantage that the catalysts used do not exhibit life times as long as desired. Life time is impaired because of depositions of acrolein polymers on the ion exchanger bed occurring over the course of operation. The acrolein polymers create an increase in pressure differential across the ion exchanger bed and hence a drop in conversion of the unsaturated aldehyde. The ion exchanger must, therefore, be renewed periodically after undesirably short periods of time.
Achievement of economic continuous operation, however, requires an adequately long life time. An object of this invention, therefore, is to improve the known process for the preparation of 3-hydroxypropanal by providing adequately long catalyst life times.
SUMMARY OF THE INVENTION
The present invention is a process for the preparation of 3-hydroxypropanal by hydration of acrolein in the presence of an ion exchange resin, wherein acrolein and water are reacted in the weight ratio of 1:2 to 1:20, at 30 to 120° C. and at a pressure in the range of 1 to 20 bar, using a chelate-forming ion exchanger which contains, bound to the polymer matrix of the polymeric resin, anchor groups of the general formula
wherein
Z is H, C
1
-C
6
alkyl, —CH
2
—CH(CH
3
)—Y′ or —(CH
2
)
o
—Y′,
Y and Y′ are equal or different: —COOH, —OH, pyridyl, or P(O)(OH)
2
, wherein the acidic functional groups may be present, in part, in the form of their salts with alkali, alkaline earth or earth metals,
m is 0, 1, 2 or 3,
n is 1, 2 or 3 for Y═—COOH, pyridyl or —P(O)(OH)
2
; 2 or 3 for Y═OH, o is 1, 2 or 3 for Y′═COOH, pyridyl or —P(O)(OH)
2
; 0, 2 or 3 for Y′═—OH,
said process being characterized in that a carboxylic acid is added to the reaction mixture.
The amount of carboxylic acid can be from 1 ppm to 50,000 ppm, preferably 10 ppm to 5,000 ppm by weight in the reaction mixture.
The process of the invention has the advantage that the addition of propanoic acid prevents an increase in the pressure differential in the reactor. Drop-off in conversion in the reactor is reduced significantly. Both these effects produce a distinctly longer life time for the catalyst.
DETAILED DESCRIPTION OF THE INVENTION
In carrying out the invention acrolein and water are supplied in a weight ratio of 1:2 to 1:20, especially 1:3 to 1:10 and preferably 1:3 to 1:6 to the hydration stage. The conversion to 3-hydroxypropionaldehyde takes place in a temperature range of 30° C. to 120° C. A temperature in a range of 40 to 90° C. is preferred; a temperature below 40° C. generally results in longer reaction times whereas a temperature above 90° C. results in a reduced selectivity and problems regarding the service life of the exchange resins. It is especially preferred if the hydration takes place at 50° C. to 80° C.
The amount of the carboxylic acid in the hydration reaction mixture can be from 1 ppm to 50,000 ppm, preferably 10 ppm to 5,000 ppm. An amount of carboxylic acid is used to maintain the pH of the reaction mixture in the range of from 1 to 5.5, preferably in the range of from 4 to 5.
Preferred carboxylic acids are aliphatic carboxylic acids containing from 2 to 8 carbon atoms. Especially preferred carboxylic acids are propenoic acid and propanoic acid. Most preferred is propanoic acid.
In the temperature range below the boiling point of acrolein, the reaction can take place at normal pressure or at moderate pressure. In the case of reaction temperatures around or above the boiling point of acrolein, the work is performed under a pressure in a range of approximately 2 to 20 bars. In the preferred temperature range of 40 to 90° C., a pressure in a range of 2 to 5 bars is preferred.
The hydration is generally carried out up to an acrolein conversion in a range of 30 to 90% or above; a conversion of 40 to 90% and especially 50 to 80% is preferred.
The hydration can take place either discontinuously or continuously and known reactors such as agitator reactors, loop reactors, floating bed reactors, fluid bed reactors and fixed bed reactors can be used. The last-named reactors are preferred over loop reactors and agitator reactors. The residence time and temperature in a fixed bed reactor containing a chelate-forming ion exchanger are controlled in such a manner that the desired acrolein conversion is achieved with a single passage of the reaction mixture through the reactor.
After separation of the ion exchanger, which usually takes place by means of sedimentation or filtration or results by itself when using a resin bed (as is customary, for example, in softened water preparation), the reaction mixture is freed, to the extent necessary, of non-reacted acrolein. The separation of the acrolein can be realized in a known manner, especially by means of distillation, preferably under reduced pressure and temperatures below 80° C. The recovered acrolein can be fed back into the process after stabilization. The practically acrolein-free hydroxypropionaldehyde solution obtained can be reconcentrated before hydrogenation e.g., via a thin-layer evaporator.
A special advantage of the use of propanoic acid as the carboxylic acid in the process of the present invention is the fact that propanoic acid can be removed from the hydrated reaction mixture as an azeotrope with water and thus is not carried downstream to the subsequent (hydrogenation) stage.
As used herein, the term “earth metal” is intended to designate the elements Al, Sc, Y, La and the 14 lanthanides; see Roempps Chemie-Lexikon.
Experiments to demonstrate the reaction of acrolein to 3-hydroxypropanal are performed in a tubular apparatus under continuous flow. The reactor consists of a double-jacketed glass tube of 3 m length and 76 mm inner diameter. The reactor is charged with ion exchanger Lewatit TP 208 (acid form) as obtained from Bayer AG. The aqueous solution is preheated to reaction temperature and pumped through the catalyst bed from the bottom up. The reactor is maintained at temperature by a thermostat. A pressure of 2.5 bar absolute is set on the exit of the reactor. Both feed and product solutions are analyzed by gas chromatography. Analyses are then used to determine conversion and selectivity of the reaction. The product solution is then hydrogenated according to the procedure of U.S. Pat. No. 5,334,778 and the hydrogenation product is distilled. After completing distillation, the content of propanoic acid in the H
2
O-distillate and the purity of 1,3-propanediol in the 1,3-propanediol distillate we

Affiliated with

Also associated with

Rating

Process for the preparation of 3-hydroxypropanal does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for the preparation of 3-hydroxypropanal, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of 3-hydroxypropanal will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2467485