CS260448B1 - Method of 4-iodaniline preparation - Google Patents

Abstract

Process for preparing 4-iodoaniline by reaction of aniline with iodine in alkaline medium by removing crude 4-iodoaniline upon exclusion from aqueous medium by crystallization from solution in an aliphatic hydrocarbon of from six to six eleven carbon atoms and with normal and / or or branched chain or from them blends with olefins and non-aromatics as contained in raffinate. To a solution of 4-iodoaniline in the hydrocarbon or raffinate is added 1 to 10 vol% of indane or other substance which 4- iodoaniline dissolves well.

Description

The invention relates to a process for the preparation of 4-iodoaniline.

A method for preparing 4-iodoaniline from aniline by the action of iodine is described in the literature. The disadvantage of this method of isolation is the elimination of the product in poor purity, often in oily form. Repeated crystallization is required several times to obtain the pure product.

These drawbacks are overcome by the process for preparing 4-iodoaniline by reacting aniline with iodine in an alkaline medium according to the invention. It is based on the fact that the crude 4-iodoaniline, after its elimination from the aqueous medium, is purified by crystallization from a solution of an aliphatic hydrocarbon having six to eleven carbon atoms and of normal and / or branched chain or mixtures thereof with olefins and non-aromates as contained in raffinate. . It is further possible to add to the solution of 4-iodoaniline in wt. % of hydrocarbon or raffinate added from 1 to 10 vol% of indane or other substance that dissolves 4-iodoaniline well.

The advantages of the process according to the invention are the elimination of the product in sufficient purity and in the speed and simplicity of carrying out the process.

The invention and its effects are explained in more detail in Description 2 of the Examples for carrying out the process for preparing 4-iodoaniline according to the invention.

According to the invention, it has now been found that one to two crystallisations of aliphatic hydrocarbons such as n-hexane or raffinate, which is a mixture of aliphatic hydrocarbons, both normal (about 22%) and branched (approx. 85%), with the addition of olefins (approx. 1.5- 2.5%) and non-aromates (approx. 1%). Raffinate is the residue after the extraction of aromatics. The raffinate composition is as follows:

mol. %

2-methylhexane 0,099 2,3-dimethylpentane 0,099 3-methylhexane 0.198 trans-1,3-DMCP 0,099 n-heptane 7.34 cis-1,2-DMCP 1.19 methylcyclohexane 0.39 2,5-dimethylhexane 2.38 2,4-dimethylhexane 4.96 1,2,4-TMPC 0.20 olefins 1.78 3,3-dimethylhexane 0,099 toluene 0,099 1,2,3-TMCP 0.39 2,3,3-TMCP 0.19 2,3-dimethylhexane 3.97 2-methylheptane 10.81 4-methylpentane 5.75 3,4-dimethylhexane 1.88 3-methylheptane 18.25 n-octane 12.40 dimethylcyclohexane 8.32 ethylbenzene 0,099 isononan 14.28 p-xylene 0,099 o-xylene 0,099 n-nonan 1.98 isodecane 1.88 n-propylbenzene 0,099 m + p-ethyltoluene 0,099 1,2,4-TMB 0,099 n-decane 0,099 iso-Cn 0.198 average molecular weight overall n-paraffins 21.8254 iso-paraffins 64,881 olefins 1,78571 non-aromates 10.8135 C5 2.08333 Ce 8.73016 aromatics 0.694444

0.11

0.11

0.23

0.12

8.42

1.39 0,46

2.39

4.99 0.20 1.83 0.10 0.12 0.40 0.20

3.99 10,88

5.79

1.89

18.37

12.48

8.53

0.11

12.80

0.11

0.11

1.78

1.52

0,095

0,095

0,095

0,080

0.146

114,957

22.7616

63,353

1,82946

11.3252

2,32312

9.00211

0.73073

WITH

It has further been found that the addition of some compounds that dissolve p-iodaniline well increases the yield of crystallization such as indane. When mixed with raffinate or petrol in an amount of 1 to 10% by volume, it has a positive effect on crystallization. The crude p-iodoaniline is dissolved in the hot in said solvent, optionally with the addition of an adsorbent, for example carborafine, bentonite and the like, and upon cooling, 4-iodoaniline precipitates in crystalline form.

Example 1

220 parts by weight, i.e. 2.36 moles of aniline, 300 parts by weight, were introduced into the reaction vessel. parts, i.e. 3.6 moles of sodium bicarbonate and 2000 wt. parts of water and the mixture is cooled to 12-15 ° C, possibly by adding venom to the reaction mixture. 500 wt. parts, i.e. 1.96 mol of iodine, finely divided. The addition of iodine was carried out successively at intervals of 2-3 minutes so that all iodine was added within 30 minutes. After addition of all iodine, the mixture was stirred for 1 hour. After this time, the reaction was complete and the free iodine color practically disappeared. The crude 4-iodoaniline, which separated as a crystalline slurry, was aspirated and dried. The filtrate was stored for iodine recovery. Yield of crude product 432 wt. parts.

For purification of 4-iodoaniline, the crude product was charged to a reaction vessel of 2000 wt. parts of raffinate. The contents were heated to reflux at 75-80 ° C. After stirring the solution with white for 30 minutes, saturation occurred. The solution was transferred, possibly after filtration, to a reaction vessel cooled under ice and salt conditions under stirring. 4-iodoaniline crystallized in colorless needles. The undissolved fraction from the first crystallization was subjected to 2nd and 3rd extractions, respectively. In batch extraction, the first portion of 4-iodoaniline is colorless; Crystallization yield: 70%. Example 1 a d 2

The procedure for preparing crude 4-iodoaniline was the same as in Example 1. Crystallization was performed from 2,000 wt. parts of naphtha to which 3% of the indane was added. The further procedure was the same as in Example 1. Crystallization yield: 75%.

The process for preparing 4-iodoaniline according to the invention is useful in the chemical industry.

Claims (2)

pRedmEt v A process for the preparation of 4-iodaniline by reacting aniline with iodine in an alkaline medium, characterized in that the crude 4-iodaniline after elimination from the aqueous medium is purified by crystallization from a solution of an aliphatic hydrocarbon having six to eleven carbon atoms and normal and / or branched chain or The invention is based on a mixture thereof with olefins and non-aromatics as contained in the raffinate. 2. A process according to claim 1, wherein from 1 to 10% by volume of indane or other substance that dissolves the 4-iodaniline is added to the solution of 4-iodaniline in the hydrocarbon or raffinate.