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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: jiujitsu123 on January 29, 2007, 11:57:52 AM

Title: [order of supstiuents naming alcohols] IUPAC names
Post by: jiujitsu123 on January 29, 2007, 11:57:52 AM

when naming the substituents is it in alphabetical order???

Title: Re: [order of supstiuents naming alcohols] IUPAC names
Post by: english on January 29, 2007, 03:34:32 PM

Always.  Lower numbers do not necessarily go with what comes first alphabetically.  If there is a tie between two groups and the same number, then the alphabetically-ordered group gets the lower number.

—OH always gets the lowest number.

In general the priorities are thus:

C=O > OH > NH₂ > alkene ~ alkyne

Carbonyls receive priority over alcohols; alcohols receive priority over amines; and amines receive priority over alkenes, which receive about the same priority as alkynes.