> > So 3,3-bromo-chloro-hexyne is not accepted! Was this type of nomenclature > accepted before and has been discontinued? >
To my knowledge, it was never accepted. There are several shorthand notations that have been in use, but IUPAC never used nomenclature like your example. The only case in which the numbers are put together is when referring to the same substituent at the same position on the hydrocarbon chain. For example, it would be 3,3-dibromohex-1-yne. At least, that's how I remember it from my chemistry-teaching days. -- Sumant Srivathsan http://sumants.blogspot.com
