FR2468579A1 - PROCESS FOR THE PURIFICATION OF N, N, DIALKYLAMINOETHANOLS - Google Patents

Abstract

Process for the purification of N, N, dialkylaminoethanols characterized by a hot treatment in the presence of a compound chosen from organic acids, ammonium salts, halogenated carbon derivatives, amino alcohol hydrochlorides, amino alcohol hydrobromides , amino alcohol phosphates, anhydrides and acid halides, followed by distillation in a column of 10 or more actual trays.

Description

- 1 -

The present invention relates to a process for purifying

  fication of the alkanolamines corresponding to the general formula R \ N - CH2 CH20H in which R and R1 are radicals R1 alkyls of identical or not structure, linear or branched, preferably of the form methyl, ethyl, propyl, isopropyl,

  butyl, isobutyl, tertiobutyl, etc ...

Depending on the method of preparation commonly used, ethylene oxide reacts under pressure, in the liquid phase, at 100 - 150eC with the dialkylamines R - NH - R1 o R and R1 are identical or not, linear alkyl radicals of the form methyl, ethyl, propyl, etc ... or branched in the isopropyl, isobutyl, tert-butyl form, etc. The reaction leads

R

  to addition compounds with structure N - (CH2-CH2-0) nH Ri

where n = 1, 2, 3 and more.

  Among the most interesting products obtained, by their uses, are N, N, dialkylaminoethancls R \

Il N - CH 2 - EH20H, easily separable from their homolo-

R1 upper gues by distillation. A certain number of

  these monoethoxylated compounds are transformed into esters of a-

  unsaturated carboxylic cides used in the preparation of cationic flocculating agents for the treatment of

  wastewater. This is in particular the case of the esters of aci-

  acrylic and methacrylic, used as monomer to give homopolymers or with other compounds

  acrylic or methacrylic to lead to copolymers-

res.

  During these homo or copolymerization, the pre-

  presence of impurities leads to parasitic cross-linking

resulting in a gelling of the very annoying medium in the ap-

  final application of these products in water treatment.

: - f - 2 -

= - 2468579

  The appearance of the gel has been linked to the presence of impurities initially contained in the alkanolamines.

used in the preparation of these unsaturated acid esters.

  Among the different by-products found in the N, N, dialkylaminoethanols, has been identified by chromato-

gas phase writing - mass spectrometry, and, exa-

  men infrared, a compound with a vinyl double bond whose structure corresponds to that of vinyl oxy-2

  1-ethanol CH2 = CH - 0 - CH2 - CH20H. This vinyl oxy-2 ethanol-

  1 present in N, N, dialkylaminoethanols is esterified to 2-oxy-ethyl vinyl acrylate or methacrylate during

  the manufacture of dialkylamide acrylates or methacrylates

noethyl. This impurity comprising two double bonds

  is at the origin of the crosslinks observed during the poly-

  merits. It has indeed been found that very low contents, greater than 20 ppm, of vinyl oxy-2 ethanol-1 are

  sufficient to make the dialkylaminoethanols, thus pol-

  polished, unsuitable for the manufacture of cationic flocculants.

In an attempt to eliminate this drawback, the tech-

  classical purification techniques, in particular the distillation

have proved either to be insufficient to bring the envinyl-2-oxy-ethanol-1 content, initially from 500 to 1,500 ppm, to a value acceptable for their application, or

  too difficult technically to be economically unreliable

industrializable.

  The object of the invention resides in the fact that a preliminary treatment of the N, N, dialkylaminoethanols by suitable chemical reagents, lowers the content of vinyl oxy-2-ethanol-1 to a value low enough for a distillation in a column to be rectified from 8 to 10 trays

real allows to obtain a perfect purity amino alcohol

  suitably suited to its application, while in the absence of this treatment, a distillation column of 50 to 60 trays

  is barely sufficient in the case of N, N, dimethylamino-

  ethanol, the difference in boiling points reaching

AT. -.- ..:

- 3 -

4 C only.

The efficiency of the purification process is ensured by controlling the elimination of vinyl oxy-2 ethanol-1 in

gas chromatography on a capillary column.

The process for purifying N, N, dialkylamino-

ethanols is characterized by a heat treatment to remove

  nation of vinyl oxy-2 ethanol-1, using inorganic compounds

  ganic or organic constituted more particularly by

organic acids, ammonium salts of organic acids

  nic or inorganic, halogenated aliphatic or aromatic carbon derivatives, hydrochlorides, bromohydrates and phosphates of amino alcohol as well as by anhydrides and

acid halides. Not all inorganic compounds

not act with vinyl oxy-2 ethanol-1 and among them, we

  may mention the alkali metal salts of inorganic acids

  nics such as chlorides, nitrates, sulfates, perms

sodium or potassium ganates.

  Among the compounds falling within the scope of the

  vention are mentioned for example, without this list being exhaustive: - Ammonium salts such as acetate, oxalate, chloride, bromide, iodide, sulfates, phosphates; - Organic acids such as acetic acid,

  citric, oxalic, monochloracetic, dichloracetic, tri-

chloracetic, mono, di and tribromacetic, trifluoroacetic, paratoluene sulfonic; - Halogenated carbon derivatives such as carbon tetrachloride, chloroform, bromoform, iodoform, chlorobromoform, carbon tetrabromide, carbon tetraiodide, 2-chloro-2-methyl-propane, 2-bromo-2-methyl propane, benzyl chloride, bromide benzyl; - Amino alcohol hydrochlorides and hydrobromides such as mono, di or triethanolamine hydrochlorides, -4-

  N, N hydrochloride, dimethylaminoethanol, chlorhy-

  N, N drate, diethylaminoethanol, N, N phosphate,

  dimethylaminoethanol, -N, N phosphate, diethylaminoetha-

nol, hydroxylamine hydrochloride, hydrochloride

  drazine, phenylhydrazine hydrochloride; - Anhydrides and acid halides such as acetic anhydride, acetyl chloride, bromide

  acetyl, thionyl chloride, hydrochlorine sulfu-

risk.-

  In accordance with the present invention, the treatment agent is used in a mass concentration of 0.1 to%, preferably 0.2 to 2%, this concentration being calculated relative to the alkanolamine. The treatment takes place at a temperature of 90 to 2000 C, preferably

120 to 150 C, at atmospheric pressure or under pressure up to

only at 10 bars, the treatment time can vary from 2 to

hours and more preferably 6 to 24 hours. The te-

  neur in vinyl oxy-2 ethanol-1 is greatly reduced and in practice reduced to 100 - 150 ppm, although it can be reduced to only a few ppm if the concentration of

  chemical reagents, temperature and processing time

  are carefully chosen. A residual content of 150 ppm vinyl oxy-2 ethanol-1 is tolerable because the distillation of the crude reaction mixture in a distillation column of 8 to 10 actual trays at most, which follows the treatment, then makes it possible to bring the content at the desired value, the treatment continuing in the boiler

  the column. This distillation is also essential

  ble to separate the monoalcanolamines, in particular the N, N, dimethylaminoethanol and N, N, diethylaminoethanol from their higher counterparts forming during the reaction of

  synthesis. When applying the purifying treatment.

  This distillation also allows the separation

  ration of excess chemical reagent and by-products that appeared during the vinyl oxy-2 removal treatment

ethanol-1 .. -.

. ... DTD: - 5 -

  The present invention is illustrated by the examples

  ples, the list not being exhaustive

EXAMPLE 1.

  A solution of dimethylaminoethanol containing 1500 ppm of vinyl oxy-2 ethanol-1 heated at 2000C under bars of nitrogen pressure for 3 hours, exhibits, after cooling, no change in the content of

vinyl oxy-2 ethanol-1.

Distillation under atmospheric pressure and on a column with metal lining of 8 real trays with a reflux rate of 10 to 1, gives a distillate still containing 75 ppm of vinyloxyethanol starting from a solution.

  of N, N, dimethylaminoethanol containing 500 ppm of the impurity.

EXAMPLE 2.

In a 250 cm flask surmounted by a condenser, g of dimethylaminoethanol containing 540 ppm of vinyl oxy-2 ethanol-1 are heated at reflux at 1350C for 24

  hours in the presence of 0.2% by weight of sodium chloride.

  The vinyloxyethanol content remains unchanged, the small variations observed being within the precision limits

of the analytical method.

EXAMPLES 3 to 5.

  No significant change in the content of

  vinyloxyethanol is only observed by operating under the conditions

  tions of Example 2 with 0.3% by weight of potassium nitrate or 0.5% by weight of sodium sulfate relative to dimethylaminoethanol containing 540 ppm of vinyloxy6thanoL

EXAMPLE 6.

  Treatment with 0.6% by weight of potassium permanganate at 1350C on the solution used in the examples

  3 to 5, is negative after 6 hours of reflux heating.

- 6 -

EXAMPLES 7 to 12.

In the apparatus used for the previous tests

teeth, 200 g of N, N, dimethylaminoethanol containing 350 to 650 ppm of vinyloxyethanol are treated at 135 C at atmospheric pressure. Reagents and conversion rates of

vinyl oxy-2 ethanol-1 are collected in the following table

  boast. The distillation on a column with metallic packing

  than 8 real trays with a reflux rate of 10 to 1,

  produces a distillate containing less than 10 ppm vinyloxy-

ethanol (V.O.E.).

EXAMPLES 13 to 15.

  By operating under the conditions of the examples before-

  above but in the presence of water, the table below

seems the conversion rates of vinyl oxy-2 ethanol-1 after

B hours of heating at 125 C. Distillation after treatment

tement on the column defined above allows to obtain

less than 10 ppm V.O.E. in the distillate.

Example Reagents Concentra- Concentra- Rate of Cons

  N tion tion V.O.E. reagent version before processing V.O.E. % (mass%) ppm 7 Ammonium chloride 0.35 500 76 8 Ammonium bromide 0.23 500 66 9 Ammonium iodide 0.35 640 74 Citric acid 0.17 350 81.6 11 Oxalic acid 0.35 350 61.3 12 Acid p. sulfonic toluene 1,350 61.6 - 7 -

EXAMPLE 16.

  By operating according to Example 13 but with a heating time of 24 hours at 125 C, 88% of the vinyloxyethanol

are transformed.

EXAMPLE 17.

By operating according to Example 13 with a concentration

  tion in 4% reagent and 4% water, 99% of vinyl oxy-2 ethanol-1 are transformed after 24 hours of heating at C.

EXAMPLE 18.

In a 5 liter flask, 4 kg of dimethylamino-

ethanol are treated at 1200C with 9 g of carbon tetrachloride. After 10 hours, the vinyloxyethanol content goes from 300 ppm to 120 ppm. Distillation on a column with metal lining of 8 real trays gives a distillate

  containing less than 10 ppm vinyloxyethanol.

EXAMPLE 19.

  Heating 3 kg of dimethylaminoethanol contains

  nant 1,780 ppm of vinyl oxy-2 ethanol-1 with 0.5% by weight of carbon tetrachloride, -at 110 C, makes it possible to obtain a

content of 50 ppm of vinyloxyethanol, i.e. a conversion rate

  98% ion o after 18 hours of heating. Distillation Example Reagents Concen-% H20 Content in NO V content Con tration version of the reagent before treatment V.O.E. % i% mass ppm

,,,,,,,

  13 Ammonium chloride 0.7 2.1 525 76.5 14 Citric acid 0.7 0.7 620 83, 7 Oxalic acid 0.35 0.35 620 74.1 1D on a column with metal lining of 10 trays

  real gives a distillate containing less than 10 ppm of vinyl-

oxyethanol.

EXAMPLES 20-21-.

  By operating for 6 hours at 130 ° C. with bromoform or

iodoform, the following results are obtained from

shot of N, N, dimethylaminoethanol containing 640 ppm of vinyl

oxy-2 ethanol-1.

  The subsequent distillation on a garaging column

  metallic weaving of 8 real trays gives a distillate

  containing less than 10 ppm vinyloxyethanol.

EXAMPLES 22 to 29.

  In a 500 cm3 flask, 200 g of N, N, dimethyl-

  aminoethanol from the synthesis reactor and containing 500 ppm of vinyloxy6thanol are treated at 130 C for

  6 hours Reagents and vinyl conversion rates

oxyethanol are collected in the following table. The dis-

  tillation on a column packed with B real trays

produces a distillate containing less than 10 ppm vinyloxy-

ethanol.

  Example Reagents Concentration Conversion rate

N reagents of V.O.E.

% mass %

Bromoform 0.6 91.6 -

21 Iodoform 0.95 80 -. -1 24t68579 -9 - 1 0

EXAMPLE 30.

  By heating with stirring for 5 hours at 120 ° C., 200 g of N, N, dimethylaminoethanol containing 500 ppm

of vinyl oxy-2 ethanol-1, in the presence of 18 g of chlorhy-

  dimethylaminoethanol drate, 98.1% of the impurity is transformed. The subsequent distillation on a column with metal lining of B real trays gives a distillate

  containing less than 10 ppm vinyloxyethanol.

EXAMPLE 31.

By heating in an autoclave of 10 1, 2 kg of N, N, dimethylaminoethanol coming from the synthesis reactor, at the temperature of 2000C for 2 hours, in the presence of 40 g of ammonium chloride, the vinyloxyethanol content increases from 540 ppm to 130 ppm, the pressure reaching 6.5 bars in the autoclave during heating. Distillation on a column with 10 real trays following this treatment makes it possible to obtain a content of 10 ppm of vinyloxyethanol in the

  N, N, dimethylaminoethanol recovered.

Example Concentra Reagents- Conversion Rate

V.a.E.

  mass% 6X 22 2-bromo-2-methyl propane 0.5 68 23 Acetyl bromide 0.3 76.5 5 24 Acetyl chloride 0.4 74.6 Thionyl chloride 0.3 91.5 26 Acetic anhydride 0 , 6 75 27 Triethanolamine phosphate I 66 28 Hydroxylamine hydrochloride 0.4 78

29 Dimethylamine hydrochloride

noethanol 3 91.3. ,,, Lm,,

- 10 -

EXAMPLE 32.

By heating at reflux to -138-1400C in a flask

for 6 hours, 200 g of N, N, crude diethylaminoethanol pro-

  coming from the synthesis reactor, containing 350 ppm of vinyl oxy-2 ethanol1, in the presence of 3 g of water and 7 g of chloro

N, N hydrate, diethylaminoethanol, CH2 content = CH -

  O - CH2 - CH2OH assayed by gas chromatography

on capillary column, is only 3 ppm after treatment

  99.1% of the amount of impurities has been removed.

0. - - '

- he _

R E V E N DI C A T I 0 N S

  1. Process for the purification of N, N, dialkylaminoethanols

  characterized by hot treatment in the presence of a ceom-

  lay selected from organic acids, ammonium salts

  nium, halogenated carbon derivatives, amino alcohol hydrochlorides, amino alcohol bromohydrates, amino alcohol phosphates, anhydrides and acid halides, followed by distillation in a column of 10

real trays at most.

2. Method according to claim 1 characterized in that the treatment is carried out at a temperature between

at 200 C.

  3. Method according to one of claims 1 to 2 characters-

  laughed at in that the treatment is carried out under pressure

  between atmospheric pressure and 10 bars.

  4. Method according to one of claims 1 to 3 characters-

  laughed at in that we use a mass concentration of

compound from 0.1 to 10% calculated with respect to N, N, dialkyl-

aminoethanol.