Abstract: An object is to provide a novel organophosphorus compound which can impart flame retardancy to an amorphous resin in a smaller addition amount without deteriorating heat resistance and transparency, and also can be applied to a wide range of resins, a flame retardant containing the same, and a method for producing an organophosphorus compound.

Abstract: Provided is a method for producing an alkenyl phosphorus compound which can produce an alkenyl phosphorus compound efficiently even with a smaller amount of a catalyst used than that used conventionally, and further which can maintain catalytic activity to produce an alkenyl phosphorus compound in high yield even at a larger reaction scale, and which can also be applied to quantity synthesis at an industrial scale using a conventional batch reactor or continuous reactor. A method for producing an alkenyl phosphorus compound, comprising: a step of reacting a compound represented by the following formula (1): [In formula (1), R1 represents OR3 or R3, R2 represents OR4 or R4, and R3 and R4 represent, for example, each independently a substituted or unsubstituted alkyl group.] with a compound represented by the following formula (2): [In formula (2), R5 represents, for example, a hydrogen atom, or a substituted or unsubstituted alkyl group.

Abstract: Provided is a method for producing an alkenyl phosphorus compound which can produce an alkenyl phosphorus compound efficiently even with a smaller amount of a catalyst used than that used conventionally, and further which can maintain catalytic activity to produce an alkenyl phosphorus compound in high yield even at a larger reaction scale, and which can also be applied to quantity synthesis at an industrial scale using a conventional batch reactor or continuous reactor. A method for producing an alkenyl phosphorus compound, comprising: a step of reacting a compound represented by the following formula (1): [In formula (1), R1 represents OR3 or R3, R2 represents OR4 or R4, and R3 and R4 represent, for example, each independently a substituted or unsubstituted alkyl group.] with a compound represented by the following formula (2): R5—C?CH??(2) [In formula (2), R5 represents, for example, a hydrogen atom, or a substituted or unsubstituted alkyl group.