Abstract: A process for the preparation of a dibromopropyl ether compound having a high melting point, which comprises mixing a bis-dibromopropyl ether of tetrabromobisphenol-sulfone or tetrabromobisphenolpropane represented by the following general formula: ##STR1## in the melted state with a crystallized product of said compound at a temperature lower than the melting point of the crystallized product, and holding the mixture at a temperature of 50.degree. to 100.degree. C.According to this process, the dibromopropyl ether compound of a high melting point can be prepared without using an organic solvent.

Abstract: Bis-(4-hydroxy-3,5-dibromophenyl) sulfone is converted to an allyl ether in the presence of an alkali with allyl chloride in the presence of a bromide and/or an iodide, and/or a substance capable of forming a bromide and/or an iodide by reaction with the alkali.

Abstract: A flame retardant for polyolefins, which comprises as an effective ingredient a hardly water-soluble or water-insoluble, nitrogen-containing phosphorus compound obtained by mixing 100 parts by weight of a condensed phosphoric acid compound with 10 to 100 parts by weight of a triazine compound and heating the mixture at 100.degree. to 250.degree. C. in the presence or absence of water.

Abstract: Highly durable flame-retardant polyurethanes can be produced by the process wherein 3 mols of dibromoneopentyl glycol is reacted with 0.5 to 4 mols of phosphoric anhydride, the ester thus obtained is reacted with at least one member selected from the group consisting of alkylene oxides and haloalkylene oxides and then, the phosphorus compound thus obtained, as a portion of a polyhydroxyl component, is incorporated with another polyhydroxyl compound and reacted with a polyisocyanate component in the presence of a catalyst.