Graphene smaller amplitude and higher frequency. This phenomenon, named "membrane effect", was predicted by Lifshitz in 1952. A prediction that was published in 2015 suggested a melting point of ≈4125 K. Recent and more sophisticated modelling has increased this temperature to at least 5000 K. At 6000 K (the sun's surface having an effective temperature of 5,777 K) graphene melts into an agglomeration of loosely coupled doubled bonded chains, before becoming a gas. The carbon–carbon bond length in graphene is about 0.142 nanometers. Graphene sheets stack to form graphite with an interplanar spacing of . Graphene is the strongest material ever
Atom economy versatile and dependable, but poorly atom-economical reactions. For example, synthesis of an alcohol is readily accomplished by reduction of an ester with lithium aluminium hydride, but the reaction necessarily produces a voluminous floc of aluminum salts, which have to be separated from the product alcohol and disposed of. The cost of such hazardous material disposal can be considerable. Catalytic hydrogenolysis of an ester is the analogous reaction with a high atom economy, but it requires catalyst optimization, is a much slower reaction and is not applicable universally. It is fundamental in chemical reactions of the form A+B→ C+D that two