DE1493771C - Process for the production of a mixture of ethylenediamine bis (o hy droxyphenylessigsaure) and their mono amide - Google Patents

Description

2. The method according to claim 1, characterized in that that the saponification with a hydrochloric acid of a concentration of 41 to 43 percent by weight carried out.

The invention relates to a new, improved process for the preparation of a mixture of ethylenediamine -bis - (o-hydroxy phenylacetic acid) - hereinafter referred to as "diacid" - and the monoamide of this Acid, hereinafter referred to as "monoamide". The formulas of the compounds of this mixture are the following:

COOH

COOH

CH-

OH

- NHCH ₂ CH ₂ NH - CH

HO

35

"Diacid"

COOH CONH ₂

Ch-NHCH ₂ CH ₂ NH-CH

OH

HO

"Monoamide"

45

These compounds are described in U.S. Patents 3,005,848 and 3,028,407. Especially is the aforementioned diacid because of its widespread use as an iron chelate for remedial purposes the iron chlorosis of plants growing in alkaline soils, of great economic value. With the help of these chelates, increased crop yields can be achieved and planted areas with below average earnings results can be brought back to higher productivity.

Mixtures of the two compounds of the formulas given above were previously in the form of their Di-hydrogen halide salts, especially in the form of the di-hydrogen chloride salts, by saponification of Ethylenediamine - bis - (o - hydroxyphenylacetonitrile) produced. This saponification is usually carried out in such a way that that said dinitrile with concentrated, d. H. Treated 37% hydrochloric acid. It was found that under these conditions a larger proportion of mono-amide and a smaller proportion A lot of diacid is produced. The ratio between monoamide and diacid in the resulting mixture be carries 60: 40% to 95: 5%.

This mixture can easily be converted into the corresponding; Iron chelates are converted; you can do that The mixture can also be converted into the diacid by alkaline hydrolysis, which then leads to the corresponding, Iron chelate is implemented.

The starting material ethylenediamine-bis- (o-hy droxyphenylacetonitrile) is prepared as follows. It is made from 2 moles of salicylaldehyde and 1 mole Ethylenediamine the corresponding Schiff base, there; Disalicylidenethylenediamine, which then with 2 moles of hydrocyanic acid is converted to the corresponding dinitrile, the abovementioned starting material.

The high price of salicylaldehyde, the large number of chemical process steps required and The low overall yield in particular is responsible for the fact that the end products obtained are expensive are. The usual synthesis of the required products is therefore an expensive manufacturing process, which; one of the main reasons for this is that one is of an extensive use of this compound for Combating plant deficiency symptoms due to the lack of trace metals in the Agriculture refrains. Despite their high effectiveness, these compounds were only economical used for growing valuable and expensive plant varieties. An improvement on one of the above The factors that increase the price mentioned above are therefore extremely important.

It has now been found that a mixture of the diacid mentioned and its monoamide can be used on an industrial scale Can produce scale in yields that are significantly higher than those previously achieved could be achieved. It has thus been found that yields of 90% and more can be achieved continuously can, while so far only yields of up to 75% by the known large-scale process could achieve. These yield data and all of the following relate to the amount of used Salicylaldehyde. Are the yields achieved in the process of the invention on the dinitrile on a relative basis, these yields are usually quantitative.

The invention relates to a process for the preparation of a mixture of 'ethylenediamine-bis- (o-hydroxyphenyl acetic acid) and their monoamide, by saponification of ethylenediamine-bis- (o-hydroxyphenylacetonitrile) with concentrated hydrochloric acid, which is characterized in that saponification is carried out with a hydrochloric acid concentration greater than 40 percent by weight.

The step according to the invention for achieving such high yields of reaction products consists that is, in the fact that for the saponification of the dinitrile hydrochloric acid of a concentration of more than 40 percent by weight, preferably from about 41 to 43 percent by weight, is used. The successful one Use of such highly concentrated hydrochloric acid is surprising and unexpected. The ones in the trade The most concentrated hydrochloric acid available and which can be produced under normal conditions has a Hydrogen chloride content of 37 percent by weight.

It cannot be explained why about 42 weight percent hydrochloric acid caused the noticeable increase in yield causes. In addition, it was found that the emergence of certain undesirable By-products such as B. the corresponding diamide

and precursors of lactams, is reduced at the same time; such lactam precursors are e.g. Tie Contain reaction products of the alkaline hydrolysis to diacid.

In a preferred embodiment of the process of the invention, the dinitrile is slurried in toluene and cooled to about 5 ° C. To this end, the approximately 42 percent strength by weight hydrochloric acid, cooled to 0 ° C., is added to this dinitrile slurry within 3 to 5 minutes while stirring and then stirred for a further 5 minutes. The batch is then left to stand for about 10 minutes, the temperature rising to about 20.degree. During this time, the hydrochloric acid converts the dinitrile into a water-soluble compound and two layers are formed. The lower, aqueous layer is separated from the toluene and ^{stirred in a vessel at a temperature of about 30 °} C. for about 2 to 3 hours to complete the reaction. The reaction mixture is then slowly heated to about 40 ° C. over about an hour. The batch is then diluted with the same amount of water as hydrochloric acid is present and heated to 60 ° C. for about 1 hour. The mixture of diacid and monoamide is then filtered off in the form of the dihydrochloride.

As already mentioned, is a hydrochloric acid with a concentration of 41 to 43 percent by weight and no longer available in stores. You must therefore by mixing 41 to 43 parts of anhydrous, gaseous Hydrochloric acid with 59 to 57 parts of water with cooling in a suitable vessel which, for. B. with a heat exchanger type cooled absorber can be manufactured. But you can also Commercially available concentrated, i.e. 37% by weight, hydrochloric acid with cooling with a sufficient Mix amount of anhydrous hydrogen chloride gas to bring the concentration to 41 to 43 percent by weight bring to. For this purpose, anhydrous hydrogen chloride gas can be poured into a glass-lined one Introduce the stirred kettle into concentrated hydrochloric acid while cooling the vessel jacket to remove the heat of absorption.

Instead of using about 42 weight percent hydrochloric acid directly, which is the preferred Execution of the process of the invention represents, since the highest yields are obtained thereby it is also possible to carry out the process in practice using commercially available concentrated hydrochloric acid to be used, but adding the concentrated hydrochloric acid to the cooled reaction mixture introduces sufficient anhydrous hydrochloric acid gas to reduce the concentration of the hydrochloric acid to about 41 to 43 weight percent increase. This process also gives very good yields, which are only slightly below those that result from the direct use of about 42 weight percent Hydrochloric acid can be achieved.

Another embodiment of the process consists in that one of a cooled mixture Commercial concentrated hydrochloric acid and concentrated 96% sulfuric acid to carry out the Saponification of the dinitrile used. The yields here do not quite correspond to those at direct use of about 42 weight percent hydrochloric acid can be achieved. But you can anyway A noticeably improved yield can also be achieved in this way, since the addition of more concentrated Sulfuric acid to concentrated hydrochloric acid causes an instantaneous release of hydrogen chloride. Such a mixture is the source of a hydrochloric acid with the concentration in the order of magnitude of 42 percent by weight.

While the concentration of the hydrochloric acid used for saponification is extremely important, the amount of hydrochloric acid to be used is of no particular importance. In the process variants described below, Nian uses between 80 and 90 kg of fuming hydrochloric acid per 0.4 to 0.5 kg of dinitrile; but it is also possible to use the hydrochloric acid in amounts between 45 and 135 kg and more.
As explained above, the saponification of the dinitrile can be carried out by gradually increasing the reaction temperature over certain periods of time. However, it is also possible to keep ^{the reaction temperature between 20 and 30 ° C. for about 8 to 12 hours.} The latter procedure is particularly indicated if you want to obtain an end product with a high proportion of monoamide. In the following examples, some of which are presented in tabular form, the process of the invention, including the preparation of the starting materials, is explained in more detail using technical approaches.

example 1

Production of the dinitrile

A 1901-capacity reaction vessel lined with glass and provided with a jacket is provided with Filled with water, heated the water to the boil and drained it again from the vessel. 43 kg of toluene, 10.3 kg 98% salicylaldehyde (0.0815 kg-mol) and 2.7 kg of 92% ethylenediamine (0.0417 kg-mol) are then added filled into the vessel. The mixture is heated to reflux temperature and the water formed removed. The entire batch is held at 113 ° C. for one hour.

The reaction mixture is then cooled ^{to about 40 °} C. with water and then to 5 to 10 ^{° C. with a salt brine.} 0.45 kg of glacial acetic acid are then added to the mixture and 2.5 kg (0.091 kg-mol) of hydrocyanic acid are then added over a period of about 5 minutes. The reaction mixture is then allowed to react for a further 3 hours, the temperature being kept at 30 ° C. or below with water cooling.

Acid saponification

This reaction mixture containing the dinitrile is cooled to about 5 ° C. by means of a brine. ^{80 kg of 42% strength hydrochloric acid, cooled to 0 °} C., are then added to this mixture with stirring over the course of 5 minutes, the strong cooling being maintained. Stirring is continued for an additional 5 minutes and the mixture is allowed to settle for about 10 minutes. During this time the temperature rises to around 20 ° C and two layers are formed.

The lower, aqueous layer is blown with air under pressure into the saponification vessel with a capacity of 115 liters, which is lined with glass on the inside and provided with a jacket. The mixture is stirred with water cooling for 2 to 3 hours, during which time the temperature is 30 ° C. The mixture is then slowly warmed to 40 ^° C. and kept at this temperature for one hour. The mixture is then diluted with

19 to 301 water from the previous batch, heats the diluted mixture to 60 ° C and holds it 1 hour at this temperature. The reaction product is then on a porcelain filter with vacuumed with a polyethylene filter cloth. The filter cake is washed with water.

The following Table I shows the results which were obtained with different approaches.

Example 2

In other approaches 37% hydrochloric acid was used together with 96% sulfuric acid. the Results of these tests are summarized in Table II.

Example 3

In two laboratory tests, in which 125 g of 96% sulfuric acid and 810 g of 37% hydrochloric acid were used and then used 275 g of 96% sulfuric acid and 900 g of 37% hydrochloric acid, the yields were of diacid and monoamide 83.1% in the first and 84.7% in the second attempt.

In another laboratory test, about 40 g of anhydrous hydrochloric acid gas was allowed into the reaction mixture flow in before adding 900 g of 37% strength hydrochloric acid; the yield of the desired reaction product was 86.4%.

Table I.

Technical approaches Moist press cake made from diacid and monoamide

approach
No. g-moles
Schiffsche
base g-moles
HCN Max.
Reaction
temp.
⁰ C Weight
HCl
(kg) Conc. HCl
in
Weight
percent separation
Temp. Reaction
time
(Min.) Max.
Temp.
⁰ C Weight
wetter
cake
(kg) Content of
Diacid
and
Monoamide
in % yield
% the
theory 1 41 91.6 27 79.5 42 17th 10 27 34.2 45.7 88.1 2 41 90.4 26th 81.6 42 23 10 27 41.3 37.7 87.9 3 41 91.6 16 79.5 42 21 10 31 38.8 38.8 85.0 4th 41 90.4 --- 79.5 43 14th 4th 40 32.9 47.4 88.0 5 41 91.6 25th 79.5 42 - 60 25th 30.2 53.1 90.3 6th 41 91.6 25th 81.6 42 12th 4th 48 41.9 37.0 87.9 7th 41 91.6 - 79.5 42 22nd 3 40 47.0 35.6 94.6 8th 41 91.6 32 81.6 43 29 60 29 42.6 36.4 87.7 9 41 90.4 27 79.9 42 22nd 4.5 85 40.1 38.8 88.1 10 50 112 34 90.8 42 28 4th 25th 66.7 27.5 85.4

Table II

Technical approaches Moist press cake made from diacid and monoamide

approach
No. g-moles
Schiffsche
base g-moles
HCN Max.
Reaction
temp.
⁰ C Weight'
37%
HCl
(kg) Weight
96%
H ₂ SO ₄
(kg) separation
Temp.
⁰ C Reaction
time
(Min.) Max.
Temp.
⁰ C Weight
wetter
cake
(kg) Content of
Diacid
and
Monoamide
in % yield
% the
theory 1
2 50
50 113
112 27
25th 72.6
73.0 22.6
22.6 25th
15th 5.5
12th 22nd
25th 47.2
59.5 36.9
31.3 81.1
86.5

Claims (1)

Patent claims: 1. Process for the preparation of a mixture of ethylenediamine - bis - (o - hydroxyphenyl acetic acid) and their monoamide, by saponification of ethylenediamine - bis - (o - hydroxyphenylacetonitrile) with concentrated hydrochloric acid, characterized in that the saponification with a hydrochloric acid concentration greater than 40 percent by weight.