NOVELTY - Manufacture of ( beta )-hydroxy aryl ether (Ia) or its derivatives involves reacting phenol (I) with oxirane (II) in presence of transition metal nanoparticles catalyst system and a solvent, stirring and diluting the reaction mixture with solvent system, separating organic layer, recovering transition metal nanoparticles from the aqueous layer by concentrating aqueous layer, concentrating the organic layer to obtain crude product comprising ( beta )-hydroxy aryl ether, and purifying the crude product to obtain pure ( beta )-hydroxy aryl ether (Ia) and M(0) nanoparticles (III).    USE - Manufacture of ( beta )-hydroxy aryl ether or its derivatives for preparing drug chosen from guaifenesin, mephenesin, chlorphenesin, propranolol and naftopidil (all claimed), moprolol and ranolazine for treatment of cold and cough, and as muscle relaxants, and cardiovascular drugs.    ADVANTAGE - The method enables efficient and environmentally-friendly manufacture of ( beta )-hydroxy aryl ether or its derivatives with high purity, reduced usage of reusable metal nanoparticles as catalyst, and easily available reactants, within short period of time.    DETAILED DESCRIPTION - Manufacture of ( beta )-hydroxy aryl ether of formula (Ia) or its derivatives involves reacting phenol of formula (I) with oxirane of formula (II) in presence of transition metal nanoparticles catalyst system and a solvent, stirring the solution at 40-100 degrees C for preset time, diluting the reaction mixture with solvent system for recovering catalyst system, separating the organic layer from the aqueous layer, optionally recovering transition metal nanoparticles from the aqueous layer by concentrating the aqueous layer, concentrating the organic layer to obtain crude product comprising ( beta )-hydroxy aryl ether, and purifying the crude product by column chromatography to obtain pure ( beta )-hydroxy aryl ether (Ia) and M(0) nanoparticles (III).    Ar1=aryl optionally substituted by halo, alkyl, alkoxy, alkyloxy, alkoxycarbonyl, alkylcarbonyl, formyl, nitrile or nitro, or naphthyl;    R1=H, alkyloxy, alkoxycarbonyl, alkyl, vinyl, hydroxy, hydroxyalkyl, di-substituted aminoalkyl, naphthyl, alkylamino, dialkylamino, optionally substituted aryl, thioaryloxy, aryloxy optionally substituted by halo or acetyl;    R2=H, or aryl optionally substituted by halo or alkyloxy;    R3=H or alkyl;and    M(0)=metal.