Abstract: In the production of 2-chloropropionaldehyde by the hydroformylation of vinyl chloride in the presence of a rhodium catalyst in combination with a base, the activity of the catalyst can be improved significantly by maintaining the concentration of produced 2-chloropropionaldehyde in the reaction solution at not higher than 10%.Further, it is possible to continue the reaction for a long period of time while maintaining the activity of the catalyst at a high level by carrying out the reaction in a water insoluble or hardly soluble solvent simultaneously with water extraction, separating the catalyst solution and the extraction water from each other, separating 2-chloropropionaldehyde from the extraction water by distillation or similar means so as to lower its concentration to a given level or below, and using the extraction water again after subjecting it to an anion exchange treatment.

Abstract: A process for the production of 2-chloropropionaldehyde from vinyl chloride, carbon monoxide and hydrogen which comprises using a rhodium compound and a trivalent organic phosphorus compound or the oxide of a trivalent organic phosphorus compound as a catalyst and carrying out the reaction under the co-existence of an acid the pka of which is in the range of 0.5-5, the oxide, hydroxide or a weak acid salt of an alkali metal or alkaline earth metal, or a buffer solution.

Abstract: This invention relates to a process for preparing 2-chloropropionaldehyde (2-CPA) by using vinyl chloride, carbon monoxide and hydrogen as raw materials. Although processes making use of cobalt catalysts have conventionally been known, it is disclosed herein that by using a rhodium compound and a nitrogen- or phosphorus-containing Lewis base in combination as a catalyst, the reaction is allowed to proceed at temperature and pressure lower than those required for such conventional processes and the selectively toward the intended product is improved. It is also disclosed that by causing water to exist in the reaction system and using a water-insoluble organic solvent, fractionating the reaction mixture into a water layer and an organic layer after the reaction and then collecting 2-CPA from the water layer through distillation, extraction or the like, the rhodium compound contained substantially in its entirety in an organic layer can be reutilized in the form of its solution.