Method for reducing iodine compound level in product mixture containing carboxylic acid and at least one alkyl iodide

FIELD: industrial organic synthesis.

SUBSTANCE: method comprises contacting vapor-phase mixture at 150-205°C with alkali and/or alkali-earth metal carboxylate dispersed on activated carbon resulting in conversion of alkyl iodides into corresponding carboxylic acid esters, while iodine becomes bound in the form of inorganic iodide.

EFFECT: facilitated freeing of carboxylic acid product from organic iodine compounds.

4 cl, 2 tbl, 32 ex

 

The present invention relates to technology for removal of iodine from iodine-containing compounds, more particularly to a method of reducing the amount of iodine compounds in the mixture of products containing carboxylic acid and at least one alkylated.

It is well known that the industrial production of acetic acid obtained promoted by methyliodide carbonyliron methanol and/or dimethyl ether and/or methyl acetate, rhodium or iridium catalysts, the final product, in order to satisfy the requirements of consumers, in many cases, must contain a very low number (less than 6 parts per billion by weight (billion shares)of iodine. Approximately 50% of global production of acetic acid is used to produce vinyl acetate catalytic way. Iodine, even in very low concentrations, significantly deactivates the catalyst of this process. The presence of iodine in acetic acid due to the use of methyliodide and/or itestosterone acid as acetalization when carbonyliron methanol and/or dimethyl ether and/or methyl acetate. A large part of iodine in the crude acetic acid is present in the form of methyliodide, while smaller amounts are present in the form itestosterone acid and higher alkylated. Methyliodide easily CTD is pouring by distillation and recycled to the reactor. A large part of itestosterone acid can also be regenerated. Residual iodine in the product, mainly higher (C2-C8-alkylated harder to remove. Often mention hexalite, as this compound is especially causes problems when removing by distillation because the boiling point is very close to the boiling temperature of acetic acid. The higher concentration of alkylation usually is of the order of 100-1000 billion shares (0.1 to 1 million shares).

There are several ways to clean the crude carboxylic acid and/or acetic acid and/or derivatives thereof. Most of these methods, however, refer to cleaning in the liquid phase. Thus, several patents describe the use of resin capable of exchanging ions of silver, palladium, mercury, and/or rhodium (US patents 4975155, 5220058, 5227524, 5300685 and 5801279) to reduce the level of iodine in the flow of carboxylates in the liquid phase. Also describes the purification of the addition of oxidizing agents, for example, in patent US 5387713, which describes the use of hydrogen peroxide in the liquid phase, and in the patent US 5155265, which describes the use of ozone as a cleaning agent in the liquid phase. In the patent US 5457230 described the use of activated carbon for the removal of iodine from the mixture of products containing acetic acid and iodine compounds.

Closest to the proposed method assetseeking in the application DE 2109146 way to reduce the iodine content in the mixture of products of various iodine-containing streams, comprising contacting the medium containing iodine or its compounds, for example, methyliodide, in the vapor phase in the form of vapor and/or gases, possibly at elevated temperature, for example, at 150°With sorbent impregnated with silver nitrate.

The objective of the invention is the removal of iodine from the containing carboxylic acid and alkylated mixture of products from the conversion of alkylation in alkylcarboxylic.

The problem is solved, we offer a way to reduce the iodine content in the mixture of products containing carboxylic acid and at least one alkyl iodide, comprising contacting the mixture in the vapor phase at a temperature of from 150 to 205°With carboxylate alkaline and/or alkaline-earth metal dispersed on charcoal.

As carboxylate alkali and alkaline earth metal is preferably used acetate, in particular, sodium acetate, potassium and/or cesium.

On contact with activated carbon preferably serves a mixture of products containing the carboxylic acid is acetic acid.

In accordance with the present invention unexpectedly found that when acetic acid contaminated with alkylidene in a concentration of from 0.1 to 3000 million shares, enter into contact in the vapor phase at these temperatures with the specified absorbent, alkylate the s into the corresponding allylacetate, while iodine is linked in the form of inorganic (non-volatile) iodide in the absorbent material.

The invention is illustrated by the following examples. With examples 1-7 describe the receipt of the absorbents according to the invention and comparative adsorbent examples 8-14 show the removal of mexilitine as the sole alkylated in the original mixture of products, and the remaining examples illustrate the removal of a mixture of some alkylation from the original mixture of products. Experimental section also includes a comparison (examples 13, 20, 21, 27, 31). In all examples, the process is carried out at normal pressure.

Example 1

Obtaining potassium on charcoal (COAs/AU) as absorbent

Potassium acetate (1,96 g of 0.02 mole) dissolved in deionized water (4 ml) and diluted with deionized water and 7.5 ml of getting a clear, colorless solution. Activated carbon (10,00 g) in the form of granules 2.5 mm (Merck, surface area by the Brunauer-Emmett-Teller 1190 m2/g, of which 470 m2/g is the surface area of micropores) is brought into contact with the aqueous solution and vigorously shaken in a closed container as long as the material does not look dry or almost dry. The material is then dried in an oven at a temperature of 100°C for 16 hours, after which record that weight leaves 13,10 g, and a bulk volume which is 28 ml This material is then divided into four parts of equal weight, containing the result of 0.005 moles To each, and these parts are stored separately. This technique is used for each retrieval absorbent material.

Example 2

Absorbent receive, as described in Example 1, except that instead of take potassium acetate acetate cesium (of 3.84 g of 0.02 mol).

Example 3

Absorbent receive, as described in Example 1, except that instead of potassium acetate take lithium acetate dihydrate (2,04 g of 0.02 mol).

Example 4

Absorbent receive, as described in Example 1, except that instead of take potassium acetate dihydrate zinc acetate (4,39 g of 0.02 mol).

Example 5

Absorbent receive, as described in Example 1, except that instead of take potassium acetate tetrahydrate magnesium acetate (4,29 g of 0.02 mol).

Example 6

Absorbent receive, as described in Example 1, except that instead of 10.00 g of activated charcoal charge of 10.00 g of calcined alumina (surface area by the Brunauer-Emmett-Teller 270 m2/g).

Example 7

Absorbent receive, as described in Example 1, except that instead of 10.00 g of activated charcoal charge of 10.00 g of silicon oxide (Merck, 100 mesh).

Example 8

In a glass reactor with an inner diameter of 1.0 cm load one piece of absorbent material (bulk volume 7 ml of 0.005 mol of acetate is Aliya), obtained as described in Example 1. Glass reactor placed in a tube furnace. The lower end of the glass reactor attached to a well insulated round bottom flask, 250 ml, enshrined in the heating shell, while its upper end is equipped with a capacitor Claisen flask and receiver. Round-bottom flask equipped with a thermometer. Through the top of the glass reactor enter a thermocouple, which is enshrined in the center layer of the acetate of the metal during the distillation. Tube furnace heated to 250°and include heating the shell. In hot round bottom flask, introduce a solution of n-hexylidene (GI) in acetic acid using a peristaltic pump. During the experiment, the measured temperature in the layer of acetate is 189°±6°C. the flow Rate of support 33±8 g/H. at regular intervals of time from a flask receiver select the condensate, the weight of which is fixed to measure the flow rate, and the GI in the sample (fully gomogenizirovannom) analyze by gas chromatography - mass spectrometry is standardized. The measured concentration of KI in the raw solution is 258 billion shares (258 micrograms of mexilitine per kilogram of solution). After 20 minutes, the purified solution is collected and analyzed. The concentration of KI is 5.4 billion is. share. The experiment is carried out for 140 minutes, during this period regularly taken samples. The concentration of the KI measured in each sample, the results are shown in table 1. This example shows that at a temperature of 189°and the flow rate of 33 g/h, volume 7 ml of the adsorbent, obtained as described in Example 1, reduces the content of exisited in the stream of acetic acid from above 258 billion shares to below 6 billion shares. Moreover, this example shows that this concentration of exisited in the processing solution is maintained in the stream continuously for 140 minutes.

Examples 9-12

The process described in Example 8, is repeated except that changing absorbent, and/or changes of temperature, and/or change the flow rate, and/or alter the concentration of mexilitine untreated solution of acetic acid, as can be seen from table 1. The temperature change by changing the position in the furnace and/or a change in flow rate. For each example, the content of exisited in the treated samples is also shown in table 1. Example 9 shows that the absorbent obtained as described in Example 2, is also effective to reduce the concentration of mexilitine under the conditions listed in table 1. Example 10 shows that the adsorbent obtained in example 1 does not work as well at lower temperatures and higher flow rate compared with Example 8. However, the concentration of mexilitine still greatly reduced compared with the concentration of exisited in the raw solution. Example 11 shows that at a substantially lower temperature (155°compared with 189°in Example 8), the binder, obtained as described in example 1 is not working as well as it works at a higher temperature in reducing the concentration of mexilitine. Example 12 shows that when the volume of the layer 14 ml (two pieces of absorbent material, obtained as described in Example 1) instead of the volume layer 7 ml as used in Example 8, the low concentrations hexylidene even more.

Example 13

The process described in Example 8, is repeated except that as the absorbent using the same activated carbon instead of potassium acetate on charcoal. Temperature, flow rate, number of GI in the raw solution are listed in table 1. For each example, the content of exisited in the processed samples are also shown in table 1. This example shows that one activated carbon is apparently also effective in lowering the amount of exisited in the stream of acetic acid, and activated carbon impregnated with salts of acetates of metals. However, as shown in further Examples, one activated carbon makes only the small part of alkylation in allylacetate, and the effect of lowering the level of exisited in the stream of acetic acid, as observed in the above Example, is mainly chromatographic effect.

Example 14

The process described in Example 8, is repeated except that the upper part of the layer of potassium acetate on charcoal (14) put another layer (7 ml) not impregnated activated carbon. Temperature, flow rate, number of GI in the raw solution are listed in table 1. For each example, the content of exisited in the processed samples are also shown in table 1. This example shows that the number of mexilitine can be reduced to below the limit of detection of this method (<0.5 billion shares).

Examples 15-32

All the following examples were carried out as described in Example 8 with the following changes: (i) a mixture of methyliodide, mutilated and octreotide in acetic acid instead of the mixture hexalite/acetic acid; (ii) the total iodide concentration in the raw solution is in most cases 0,037-0,040 M (37-40 mm), and in some cases 0,0037 M (3.7 mm); (iii) the identity and amount of adsorbent, temperature, flow rate and specific concentration methyliodide, mutilated and octreotide change, as shown in table 2. Included in table 2 for each experiment the amount of each alkali the Dida and each of the alkyl acetate is measured three to five times. For each point in time count of the used capacity of the absorbent layer (Cap. (%) in table 2):

Cap.(%)=(n(MAOIs)+n(BuOAc)+n(OctOAc))/n(M)×100%, where

n(MeOAc) - the total number of moles of acetate formed during this time;

n(BuOAc) - the total number of moles of butyl acetate formed during this time;

n(OctOAc) - the total number of moles of activityat formed during this time;

n(M) is the number of moles of metal in the adsorbent, as shown in table 2.

Similarly, for each point in time, calculate an average conversion rate of these three alkylation in acetates (Con. (%) in table 2):

Con.(%)=([Meoac]/[MeI]ls.)+([Vious]/[BuI]ls.)+([OctOAc]/[OctI]total)/3×100%

where [Meoac] is the measured concentration of acetate in purified mixture;

[BuOAc] is the measured concentration of butyl acetate in purified mixture;

[OctOAc] is the measured concentration of activityat in purified mixture;

[MeI]total - concentration methyliodide in the raw mix;

[VI]total - concentration butylated in the raw mix;

[OctI]total - concentration octreotide in the crude mixture.

1. The way to reduce the iodine content in the mixture of products containing carboxylic acid and at least one alkylated, including kontaktirovanije mixture in the vapor phase at a temperature of from 150 to 205° With carboxylate alkaline and/or alkaline earth metal dispersed on charcoal.

2. The method according to claim 1, wherein the mixture is in contact with the acetate of alkali and/or alkaline earth metal dispersed on charcoal.

3. The method according to claim 2, in which the mixture is in contact with Na acetate, and/or Cs, dispersed on charcoal.

4. The method according to one of claims 1 to 3, in which communication serves a mixture, the main component by weight of which is acetic acid.



 

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