A method of producing sulfur modified organosilane compounds that can be used in asphalt binders which method involves: combining together an organosilane or mixtures of organosilanes, a sulfide, a halogen acceptor and solvent to form a reaction mixture; and allowing the organosilane to react with the sulfide in the presence of a halogen acceptor to produce a sulfur modified organosilane compound. The sulfur modified organosilane compound can be introduced into a polymer modified or unmodified asphalt binder in which the sulfur modified organosilane compound reacts with components in the asphalt mixture to form a modified asphalt. The organosilanes used to produce the sulfur modified organosilanes can be from a source of waste products (such as Direct Product Residue) in which case the waste products can be reused in asphalt binders.