the r in a circle symbol is the registered trademark symbol.
the r in a circle symbol is the registered trademark symbol.
what is the r in a circle symbol?
the registered trademark symbol
Na
Na
the circle symbol for aromaticity was introduced by sir robert robinson and his student james armit in 1925 and popularized starting in 1959 by the morrison & boyd textbook on organic chemistry. the proper use of the symbol is debated; it is used to describe any cyclic π system in some publications, or only those π systems that obey hückel's rule in others. jensen argues that, in line with robinson's original proposal, the use of the circle symbol should be limited to monocyclic 6 π-electron systems. in this way the circle symbol for a six-center six-electron bond can be compared to the y symbol for a three-center two-electron bond.
aromatic hydrocarbon