FR2577219A1 - PROCESS FOR PURIFYING PENTACHLOROPHENOL AND ITS DERIVATIVES - Google Patents

Abstract

The process for purifying pentachlorophenol and its derivatives comprises the step of immersing the pentachlorophenol obtained by industrial manufacture in an aqueous solution or dispersion of a compound chosen from the group consisting of sodium bicarbonate, potassium bicarbonate, ammonium carbonate, ammonia and calcium carbonate. The insoluble part which is obtained by removing the solution containing the material separated by dissolution is dissolved in an aqueous solution of sodium carbonate or potassium carbonate, whereby the material which still remains undissolved is removed. An insufficient quantity of copper sulphate is added to the solution thus obtained, the deposit which forms is removed, and the pentachlorophenol and its derivatives are recovered from the solution. Use for removing harmful impurities from pentachlorophenol obtained by industrial manufacture.

Description

The present invention relates to a purification process

  pentachlorophenol and its derivatives, in which

  the harmful impurities present therein are eliminated.

  Pentachlorophenol (PCP) is manufactured industrially

  by chlorination of phenol, but the technical grade pentachlorophenol thus obtained contains as impurities

  non-phenolic neutral substances such as chlorodi-

  benzodioxins, chlorodibenzofurans, chlorinated

  diphenyl and hexachlorobenzene, etc., and

  phenolic acid substances such as chlorophenoxy-

  phenols, chlorodihydroxybiphenyls, etc., in addition to tetrachlorophenol. Among these impurities, by far the most undesirable ingredients are chlorodibenzodioxins and

  chlorodibenzofurans that are known to be strong-

  toxic substances, as well as chlorodiphenyl ethers and chlorophenoxyphenols, which are said to be the precursors of these substances because of their ease with

  which they turn into these substances.

  Therefore, it is very much hoped that for a better application of pentachlorophenol and its derivatives as agricultural chemicals, all the impurities described above are eliminated, but there is now no elimination process for any

of these impurities.

  Where the plaintiff, in view of the situation described above, has studied the process for the elimination of

  undesirable impurities described above in the penta-

  chlorophenol and its derivatives, it obtained the information

  following by the experiments shown below.

  (1) From the fact that a phenolic substance which is obtained by dipping an industrially manufactured, finely divided pentachlorophenol (hereinafter referred to as technical pentachlorophenol) into a solution of sodium bicarbonate, bicarbonate & potassium, carbonate ammonium, or ammonia, and then collecting

  the resulting solution containing the dissolved material

  and acidifying with hydrochloric acid, is a highly sublimable material, melting at 176 ° C, whose molecular weight is 245 by the neutralization titration method and 530 by the method of freezing point depression, can assume that

  this substance is chlorodihydroxybiphenyl.

  (2) From the fact that when technical pentachlorophenol is dissolved in a dilute aqueous solution of caustic soda at room temperature, a non-phenolic neutral substance separates as an insoluble material which is removable, while an acidic substance depositing this solution of caustic soda containing the dissolved matter when a small quantity of carbon dioxide is insufflated therein, melts at 196 ° C, but does not sublimate, whose molecular weight is 570 by the method of titration by neutralization, we can assume that this is

  chlorophenoxyphenol or a mixture thereof.

  (3) From the fact that a phenolic substance is obtained when a substance (copper salt of PCP) depositing this solution of caustic soda, from which the acidic substance described above was separated and removed , adding a solution of copper sulphate which contains copper sulphate in a proportion of 1 to 2% of that necessary for the complete conversion to copper salt, is decomposed by hydrochloric acid, melting at 70 ° C., present a molecular weight of 530 by the neutralization titration method, the substance must be a chlorophenoxyphenol other than chlorophenoxyphenol

obtained in paragraph (2) above.

  (4) It has been found that when a copper salt which is deposited in the solution described in paragraph (3) above, from which the deposited PCP copper salt has been separated and removed, by adding a Copper sulphate solution containing 98% of the copper sulphate required for complete conversion to copper salt is separated and discarded.

  the remaining solution is decomposed by chloroacid

  water, only pentachlorophenol is obtained.

  The present invention was thus carried out on the basis of the information obtained from the experiments described above, and the object of the invention is to provide a process for the purification of technical pentachlorophenol which makes it possible to eliminate the undesirable impurities which are therein.

  present. The present invention will be explained more fully.

below.

  The characteristic of the present invention resides

  in that the process for the purification of pentachloro-

  phenol which is obtained by industrial manufacture comprises the step of immersing this pentachlorophenol in an aqueous solution or dispersion of a compound selected from the group consisting of sodium bicarbonate, potassium bicarbonate, ammonium carbonate, sodium carbonate, ammonia, and calcium carbonate, then, after removal of the solution containing the dissolvably separated material, dissolving the remaining insoluble material in an aqueous solution of sodium carbonate or potassium carbonate and removing the material which still remains undissolved, the step of adding an insufficient amount of copper sulfate to the solution thus obtained and removing the deposits formed by separation and the step of recovering the pentachlorophenol or its derivatives from the resulting solution. The present invention is also characterized in that the method comprises the step of

  dissolve pentachlorophenol which has been obtained by

  industrial cation in a slight excess of an aqueous solution of sodium carbonate or potassium carbonate and to remove the insoluble matter, the step of dipping the deposit that has formed when the solution obtained above is acidified, in an aqueous solution or dispersion of a compound selected from the group consisting of sodium bicarbonate, potassium bicarbonate, ammonium carbonate, ammonia and calcium carbonate, and removing the solution containing the material separated by separation dissolution, the step of adding copper sulfate to the solution of the remaining insoluble material in an aqueous alkaline solution and removing the deposit which is then formed by separation, and the step of recovering the pentachlorophenol or his

derived from the solution obtained.

  In addition, the term "pentachlorophenol derivatives" means alkali metal salts (e.g., sodium salt, calcium salt, etc.), heavy metal salts (e.g., copper salt, nickel salt, etc.). ), and esters (for example lower alkyl, methyl, ethyl,

etc.) pentechlorophenol.

  In the process of the present invention, penta-

  finely divided technical chlorophenol is poured into a dilute aqueous solution or dispersion of a substance selected from the group consisting of sodium bicarbonate, potassium bicarbonate, ammonium carbonate, ammonia and calcium carbonate, and stirring during

  about 3 hours at room temperature, this is mainly

  chlorodihydroxybiphenyl which is contained in this pentachlorophenol which is removed by dissolution, after which the insoluble matter thus formed is collected and dissolved by adding it to an aqueous solution of carbonate

  sodium or potassium carbonate. In this case

  above, as the non-phenolic neutral substance and chlorophenoxyphenol are not dissolved, they are eliminated

in the form of insoluble matter.

  When the dissolution described above is carried out using an aqueous solution of sodium carbonate or potassium carbonate, when a slight excess of sodium carbonate or potassium carbonate is used, the dissolution treatment is carried out by heating at a temperature of 70-90 ° C. and 90 ° -95 ° C., respectively, but when sodium carbonate or potassium carbonate are used in excess of the theoretically required amount of two or more times, the treatment

  dissolution can be carried out at room temperature.

  In this respect it can be said that the reason why the excess described above of sodium carbonate or potassium carbonate is used in the dissolution treatment at room temperature and that it is necessary to take into account that at room temperature, sodium bicarbonate or potassium bicarbonate is formed from a portion of the sodium carbonate or

  potassium carbonate, without release of carbon dioxide.

  Similarly, in the process of the present invention, pentachlorophenol as the starting material can be first dissolved in an aqueous solution of sodium carbonate or potassium carbonate to remove the

  insoluble matter, then, after the penta-

  chlorophenol is deposited from the solution thus obtained, by immersing the deposit formed in a solution or an aqueous dispersion of a compound selected from the group consisting of sodium bicarbonate, potassium bicarbonate, ammonium carbonate, water ammonia and calcium carbonate, the soluble part of this deposit may

to be eliminated.

  This means that the industrially produced pentachlorophenol is dissolved by stirring in a slight excess of aqueous sodium carbonate or potassium carbonate solution at a temperature of 70-90 ° C and

  -95 ° C, respectively, so that the insoluble matter -

  consisting of a non-phenolic neutral substance, and mainly chlorophenoxyphenol, may be removed, and then, after the pentachlorophenol deposit, which is formed when the solution obtained above is acidified, separated and was collected, this deposit is immersed in an aqueous solution or an aqueous dispersion of a compound selected from the group consisting of sodium bicarbonate, potassium bicarbonate, ammonium carbonate, ammonia

  and carbohydrate calcium, so that it is main-

  chlorodihydroxybiphenyl that can be removed

by dissolution.

  In the process of the present invention, it is slowly added to an aqueous solution containing mainly pentachlorophenol, which is obtained by eliminating the

  non-phenolic neutral substance, chlorodihydroxyb!

  phenyl, and chlorophenoxyphenol as impurities as described above, a small amount of

  copper sulphate with stirring to remove a chloro-

  phenoxyphenol different from that described above, allowing it to be deposited in the form of copper salt, in which case stirring is continued for several hours, so that an equilibrium can be established between the substances

  dissolved in the solution and the copper salt described above

above -

  When hydrochloric acid is added to the pentachlorophenol solution obtained as described above, pentachlorophenol is then collected.

  deposited, pure pentachlorophenol is obtained which is practically

  only-free of non-phenolic neutral substances, or phenolic acids such as impurities

undesirable effects described above.

  In addition, this pure pentachlorophenol may contain a trace of tetrachlorophenol, but since this material is in fact virtually harmless in the application of pentachlorophenol as a chemical for agriculture,

there is no problem.

  In addition, when the pentachlorophenol derivatives such as copper salt, alkali salt or esters are prepared in the usual manner using the pentachlorophenol solution described above, the derivatives which are free from the impurities described above are obtained. Incidentally, the facts that could be confirmed in the present invention are respectively the following

  That the product of decomposition by chloroacid

  of the solution containing the dissolved material by immersing a technical pentachlorophenol in an aqueous solution of alkaline substance (the material dissolved in an aqueous solution of sodium bicarbonate, an aqueous solution of potassium bicarbonate, an aqueous solution of carbonate of ammonium, ammonia or a calcium carbonate dispersion) has the properties of chlorodihydroxybiphenyls according to the results of the experiments described above, that the insoluble matter which is obtained after the insoluble material from the immersion described above has been dissolved in an aqueous solution of sodium carbonate or potassium carbonate, the material which remains undissolved is again immersed in a 2% aqueous solution of caustic soda at the ahibiting temperature, and is a non-neutral phenolic,

  while the phenolic substance resulting from decomposition

  position by hydrochloric acid of the soluble portion

  presents the properties of chlorophenoxyphenols in

  results of the experiments described above, and that the phenolic substance which is obtained when

  copper sulphate is added to the solution described

  above, from which the insoluble material has been removed, the copper salt formed is decomposed by hydrochloric acid, is a mixture of pentachlorophenol with a chlorophenoxyphenol different from the chlorophenoxyphenol described

  above and having a 7CC fusion bridge.

  As explained above, in accordance with

  process of the present invention, the undesirable impurities

  The above described blends present in the industrially manufactured pentachlorophenol can be removed by effective separation to obtain a pentachlorophenol which is partially free of such impurities, so that the problem described above in the present invention can be overcome. Use of pentachlorophenol as an active ingredient in agricultural chemicals may be

overcome.

  Referring to examples, the invention will be

  explained concretely below.

Example 1

  200 g of technical pentachlorophenol milled to 0.044 mm were poured into an aqueous solution of sodium bicarbonate and, after stirring for 3 hours at room temperature, the insoluble material was collected by filtration. This insoluble material is introduced into a solution prepared by dissolving 40 g of sodium carbonate in

  1500 ml of water and it is heated to a temperature of 80-

   C. By this heating, carbon dioxide is evolved, and it follows that the pentachlorophenol present in this insoluble matter is dissolved, so that the material which remains undissolved is removed and the solution containing the material dissolved by dissolution is recovered. To this solution, 0.9 g of copper sulphate is slowly added with stirring, and after stirring for

  several hours, the deposited copper salt is removed

  By the above elimination of copper salt, one

  gets a solution containing mainly pentachloro-

  phenol. Then, adding hydrochloric acid to this solution, pentachlorophenol is deposited and

  Collect it. The yield is 166 g. Pentachloro-

  phenol thus obtained was found to contain a small amount of tetrachlorophenol, but it is practically

  free from the non-phenolic neutral substances described above.

  above, chlorophenoxyphenols, or chlorohydroxybi-

  phenyls, which are undesirable impurities.

Example 2

  200 g of industrially manufactured pentachlorophenol, milled to 0.044 mm, are introduced into a solution prepared by dissolving 45 g (a slight excess) of sodium carbonate in 1500 ml of water and heating to 70-90 ° C with stirring. In the above case, carbon dioxide is released as pentachlorophenol dissolves, so that when the evolution of gas ceases,

  the solution is filtered to remove the insoluble material.

  An aqueous solution containing 0.9 g of dissolved copper sulfate is added to the filtrate, and after stirring for several hours, the deposited copper salt is filtered off for removal. Acidifying the filtrate obtained with acid

  hydrochloric acid, all the pentachloro-

  phenol, and after adding it to 65 g of sodium bicarbonate and a suitable amount of water and stirring for 3 hours at room temperature, the solution containing the separated material is removed by filtration.

  by dissolution, and pentachlorophenol is obtained.

Yield: 168 g.

Example 3

  200 g of 0.032 mm technical ground pentachlorophenol are introduced into an aqueous solution prepared by dissolving 45 g (a slight excess) of potassium carbonate.

  in 1500 ml of water, and heating to 85-95 ° C with stirring.

  After filtering the resulting solution to remove the insoluble material, the filtrate is acidified by the addition of hydrochloric acid, and the deposit formed is collected by filtration. Then, after having poured this deposit into an aqueous solution of potassium bicarbonate and immersed in it for 3 hours with stirring, the solution containing the material separated by dissolution is removed by filtration. After washing the resulting immersion residue with water, it is dissolved in a suitable quantity of 2% aqueous solution of caustic soda.

  which gives a solution at pH 8-9, to which we slowly add

  0.9 g of copper sulphate, with stirring, and eliminates

the deposited copper salt.

  The pentachloro sodium salt is again acidified

  phenol thus obtained with hydrochloric acid to

  to deposit pentachlorophenol, which is collected.

Yield: 154 g.

Example 4

  To 200 g of technical pentachlorophenol milled to 0.044 mm is added a suitable quantity of aqueous solution of g of potassium bicarbonate and stirred at room temperature.

  room. When the release of carbon dioxide is

  The solution containing the dissolved solids is removed by filtration. To the insoluble matter

  obtained, an aqueous solution prepared in the form of

  55 g of potassium carbonate in 1500 ml of water and heated to 90-95 ° C with stirring. When the release of carbon dioxide ceases, the solution obtained is filtered to remove the insoluble material. By acidifying the solution thus obtained with hydrochloric acid, we obtain

  pentachlorophenol. Yield: 155 g.

Example 5

  200 g of technical pentachlorophenol milled to 0.044 mm were poured into an aqueous solution of potassium bicarbonate and, after stirring for 3 hours at room temperature, the solution was filtered to separate the insoluble part which was collected. The part separated by dissolution in this treatment is 15%. The insoluble portion is placed in a solution prepared by dissolving 40 g of sodium carbonate in 1500 ml of water, and is heated to 80-900C. By this heating, carbon dioxide is evolved and the pentachlorophenol present in this insoluble material is dissolved, so that the material which remains undissolved (about 8%) is removed from the solution which is collected. After slowly adding 0.9 g of copper sulfate to the recovered solution by stirring, stirring is continued for several hours, and then the deposited copper salt is filtered off for removal. Acidifying the solution obtained

  with hydrochloric acid, the penta-

  chlorophenol and collected. The yield is 166 g.

Claims (5)

  A process for purifying pentachlorophenol and its derivatives, which comprises dipping the industrially manufactured pentachlorophenol in an aqueous solution or dispersion of a compound selected from the group consisting of sodium bicarbonate, sodium bicarbonate, and the like. potassium, ammonium carbonate, ammonia, and calcium carbonate and to dissolve the insoluble part which is obtained by removing the solution containing the dissolved material in an aqueous solution of sodium carbonate or potassium carbonate, whereby the material which remains undissolved is removed, the step of adding an insufficient amount of copper sulphate to the solution thus obtained and separating the deposit which is then formed to eliminate it, and the step of recovering the   pentachlorophenol and its derivatives of the separated solution.   A process for purifying pentachlorophenol and its derivatives, which comprises the step of dissolving the industrially manufactured pentachlorophenol in a slight excess of an aqueous solution of sodium carbonate or potassium carbonate to remove the insoluble portion, the step of dipping the deposition which is formed by acidification of the solution obtained as described above, in an aqueous solution or an aqueous dispersion of a compound selected from the group consisting of sodium bicarbonate, sodium bicarbonate, potassium, ammonium carbonate, ammonia, and calcium carbonate and separating the solution containing the dissolvably separated material to remove it, the step of adding copper sulfate in an aqueous solution of alkali, in which the insoluble part obtained in the immediately preceding step has been dissolved, and to separate the deposit thus formed for removal and the step of recovering pentachlorophenol and   its derivatives of the thus separated solution.   3. Purification process according to one of the claims   1 or 2, characterized in that the amount of sodium carbonate or potassium carbonate used at room temperature is in excess of two times or   more in relation to that theoretically necessary.   4. Purification process according to one of the claims   1 or 2, characterized in that the amount of sodium carbonate or potassium carbonate used at a temperature of 70-95 C or 90-95 C respectively,   is an excess slightly greater than the theoretically necessary.   5. Purification process according to one of the claims   cations 1 or 2, characterized in that the copper sulphate is slowly added with stirring, and stirring is continued until equilibrium has been established between   the substances present in the solution and the deposit formed.