1.  Field of the Invention
The present invention relates to a brominated 1,3-dimethyl-3-phenyl-1-(2-methyl-2-phenylpropyl) indane and a method for preparing the compound. 
2.  Description of the Prior Art
There have conventionally been used bromide compounds having high heat resistance and excellent in a variety of characteristic properties such as electrical insulating properties in order to impart flame resistance to various kinds of thermoplastic resins and thermosetting resins.  In particular, in the field requiring the use of an externally added type compound having high heat resistance, there have been used brominated atom-containing aromatic compounds, i.e., aromatic compounds each having bromine atom(s) directly linked to the aromatic ring(s), such as decabromodiphenyl ether, tetrabromobisphenol A epoxy oligomer, tetrabromobisphenol A polycarbonate oligomer, brominated polystyrene and ethylene bistetrabromophthalimide.  In addition, there have newly been developed brominated atom-containing compounds such as 1,1,3-trimethyl-3-phenyl indane as disclosed in Japanese Un-Examined Patent Publication (hereinafter referred to as "J.P. KOKAI") No.  Hei 6-122637. 
The externaly added flame-resistant agents should satisfy such requirements that they must have a high decomposition temperature and that they must have good fabrication properties, i.e., they must have a melting point favorable for uniformly kneading them with a base resin.  The foregoing flame-resistant agents such as decabromodiphenyl ether, tetrabromobisphenol A epoxy oligomer, tetrabromobisphenol A polycarbonate oligomer, brominated polystyrene and ethylene bistetrabromophthalimide each has a thermal decomposition temperature of not less than 300.degree.  C., but decabromodiphenyl ether is the only example of compounds whose bromine content is not less than 70%.  However, decabromodiphenyl ether suffers from a problem in that the molding temperature should be raised up to a level of not less than 306.degree.  C. to obtain a uniform blend with a base resin since it has a high melting point on the order of 306.degree.  C. For this reason, there has usually been adopted a method in which the compound in the particulate form is dispersed in a base resin as uniform as possible.  Moreover, polybromobiphenyl ethers have given rise to public discussion, because there has been reported that they may generate brominated dioxine and/or brominated dibenzofuran when burning them at a specific temperature (Environ.  Sci.  Technol.,  1986,20, 4, pp.  404-408).  In addition, octabromo-1,1,3-trimethyl-3-phenylindane has a slightly low thermal decomposition temperature on the order of 296.degree.  C. and accordingly, there has been desired for the development of a flame-resistant agent having a higher thermal decomposition temperature.