A method has been disclosed of obtaining high purity, colourless monochloroacetic acid encompassing the chlorination of acetic acid with chlorine in the presence of a catalyst, followed by the recovery of the catalyst through vacuum distillation and purification of the obtained liquid raw product by its hydrodehalogenation by hydrogen in the presence of a palladium catalyst and then vacuum distillation.

A method of producing monochloroacetic acid (MCAA) has been disclosed encompassing (a) a stage of the direct chlorination of acetic acid with chlorine and (b) a stage of recovery of the catalyst in the form of acid chlorides from the reaction mixture before (c) a hydrodehalogenation stage characterized by the fact that the chlorination process (a) is conducted at the boiling temperature of the mixture under a pressure of 0-1.0 barg, in an excess of acetic acid with respect to the dosed chlorine gas, while the heat from the reaction is taken off mainly through the evaporation of volatile components of the mixture, followed by their condensation in the reflux condenser above the reactor and the return to the chlorination reaction, after which the reaction mixture containing monochloroacetic acid, acetic acid, dichloroacetic acid and optionally acid chlorides which are present in the mixture and, optionally, anhydrides of these acids, is feed to the vacuum distillation process (b), which is conducted continuously in the distillation column in a vacuum of 0 to 500 mbar from which volatile components of the mixture, mainly acid chlorides, as well as some acetic acid and some monochloroacetic acid are taken off as distillate and returned to the chlorination process as a result of which the catalyst of the chlorination is almost completely recovered.

A method of producing monochloroacetic acid (MCAA) has been disclosed encompassing (a) a stage of the direct chlorination of acetic acid with chlorine and (b) a stage of recovery of the catalyst in the form of acid chlorides from the reaction mixture before (c) a hydrodehalogenation stage characterized by the fact that the chlorination process (a) is conducted at the boiling temperature of the mixture under a pressure of 0-1.0 barg, in an excess of acetic acid with respect to the dosed chlorine gas, while the heat from the reaction is taken off mainly through the evaporation of volatile components of the mixture, followed by their condensation in the reflux condenser above the reactor and the return to the chlorination reaction, after which the reaction mixture containing monochloroacetic acid, acetic acid, dichloroacetic acid and optionally acid chlorides which are present in the mixture and, optionally, anhydrides of these acids, is feed to the vacuum distillation process (b), which is conducted continuously in the distillation column in a vacuum of 0 to 500 mbar from which volatile components of the mixture, mainly acid chlorides, as well as some acetic acid and some monochloroacetic acid are taken off as distillate and returned to the chlorination process as a result of which the catalyst of the chlorination is almost completely recovered.

The present disclosure provides new salts of 5-aminolevulinic acid (5-ALA) and new salts of 5-ALA esters, their preparation, formulation and use as photosensitizing agents in photodynamic therapy, diagnosis and cosmetic cares.

The present invention pertains to a process for the purification of a feed comprising monochloroacetic acid and dichloroacetic acid wherein the feed is subjected to a catalytic hydrodechlorination step by contacting it with a source of hydrogen to convert dichloroacetic acid into monochloroacetic acid in the presence of a solid heterogeneous hydrogenation catalyst comprising a Group VIII noble metal on a carrier under hydrodechlorination conditions, wherein the reaction is carried out in the presence of a catalyst enhancer which comprises a salt of a metal selected from the group of non-noble metals of Group VIII, Group VIB, Group VIIB, and Group IIB. It was found that the presence of a catalyst enhancer leads to reduced deactivation of the catalyst and/or increased activity of the spent catalyst. This allows longer production cycles, less downtime, and lower formation of side products. The catalyst enhancer preferably comprises one or more salts of one or more of nickel, cobalt, or iron, more in particular of iron. The salts preferably comprise one or more of chloride salts and acetate salts.

The present invention pertains to a process for the purification of a feed comprising monochloroacetic acid and dichloroacetic acid wherein the feed is subjected to a catalytic hydrodechlorination step by contacting it with a source of hydrogen to convert dichloroacetic acid into monochloroacetic acid in the presence of a solid heterogeneous hydrogenation catalyst comprising a Group VIII noble metal on a carrier under hydrodechlorination conditions, wherein the reaction is carried out in the presence of a catalyst enhancer which comprises a salt of a metal selected from the group of non-noble metals of Group VIII, Group VIB, Group VIIB, and Group IIB. It was found that the presence of a catalyst enhancer leads to reduced deactivation of the catalyst and/or increased activity of the spent catalyst. This allows longer production cycles, less downtime, and lower formation of side products. The catalyst enhancer preferably comprises one or more salts of one or more of nickel, cobalt, or iron, more in particular of iron. The salts preferably comprise one or more of chloride salts and acetate salts.

The present invention is directed to a process for catalytic hydrodechlorination of dichloroacetic acid, wherein hydrogen gas is contacted with a liquid feed comprising dichloroacetic acid and monochloroacetic acid to form a product stream comprising monochloroacetic acid and an off gas stream comprising hydrogen chloride and hydrogen, and wherein the product stream is contacted with nitrogen gas so as to remove hydrogen gas present in the product stream.

The present invention is directed to a process for catalytic hydrodechlorination of dichloroacetic acid, wherein hydrogen gas is contacted with a liquid feed comprising dichloroacetic acid and monochloroacetic acid to form a product stream comprising monochloroacetic acid and an off gas stream comprising hydrogen chloride and hydrogen, and wherein the product stream is contacted with nitrogen gas so as to remove hydrogen gas present in the product stream.

The present invention pertains to a process for the purification of a feed comprising monochloroacetic acid and dichloroacetic acid wherein the feed is subjected to a catalytic hydrodechlorination step by contacting it with a source of hydrogen to convert dichloroacetic acid into monochloroacetic acid in the presence of a solid heterogeneous hydrogenation catalyst comprising a Group VIII noble metal on a carrier under hydrodechlorination conditions, wherein the reaction is carried out in the presence of a catalyst enhancer which comprises a salt of a metal selected from the group of non-noble metals of Group VIII, Group VIB, Group VIIB, and Group IIB. It was found that the presence of a catalyst enhancer leads to reduced deactivation of the catalyst and/or increased activity of the spent catalyst. This allows longer production cycles, less downtime, and lower formation of side products. The catalyst enhancer preferably comprises one or more salts of one or more of nickel, cobalt, or iron, more in particular of iron. The salts preferably comprise one or more of chloride salts and acetate salts.

The present invention pertains to a process for the purification of a feed comprising monochloroacetic acid and dichloroacetic acid wherein the feed is subjected to a catalytic hydrodechlorination step by contacting it with a source of hydrogen to convert dichloroacetic acid into monochloroacetic acid in the presence of a solid heterogeneous hydrogenation catalyst comprising a Group VIII noble metal on a carrier under hydrodechlorination conditions, wherein the reaction is carried out in the presence of a catalyst enhancer which comprises a salt of a metal selected from the group of non-noble metals of Group VIII, Group VIB, Group VIIB, and Group IIB. It was found that the presence of a catalyst enhancer leads to reduced deactivation of the catalyst and/or increased activity of the spent catalyst. This allows longer production cycles, less downtime, and lower formation of side products. The catalyst enhancer preferably comprises one or more salts of one or more of nickel, cobalt, or iron, more in particular of iron. The salts preferably comprise one or more of chloride salts and acetate salts.