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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: gamerninja213 on February 24, 2013, 09:25:36 PM

Title: Absolute configuration
Post by: gamerninja213 on February 24, 2013, 09:25:36 PM

Sorry. This might seem like a very stupid question, but when assigning absolute configuration for glyceraldehyde, why is it that CHO gets priority over  HOCH2 ?

Title: Re: Absolute configuration
Post by: camptzak on February 24, 2013, 10:18:10 PM

The CHO carbon has two bonds to oxygen and one bond to hydrogen. The HOCH₂ carbon has two bonds to hydrogen and only one bond to oxygen. Since the CHO has more bonds to an element of higher atomic number, it has priority.

Title: Re: Absolute configuration
Post by: Dan on February 25, 2013, 03:11:27 AM

See also: http://en.wikipedia.org/wiki/Cahn%E2%80%93Ingold%E2%80%93Prelog_priority_rules