Nomenclature PDF

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nomenclature handout...

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To Clarify 1. when naming branched alkanes where prefix’s di, tri, tetra, penta (etc) are involved: a) if the prefix relates to groups attached directly to the chain the prefix DOES NOT count when considering alphabetical order – see example below. 3-ethyl-4,5-dimethyloctane NOT 4,5-dimethyl-3-ethyloctane note: in this case the ‘di’ did not count for alphabetizing! b) if the prefix relates to groups attached to a branch the prefix DOES count when considering alphabetical order – see example below. This rule can be simplified by stating that if the prefix is in brackets it counts when considering alphabetical order. 5-(1,1-dimethylethyl)-3-ethyloctane NOT 3-ethyl-5-(1,1-dimethylethyl)octane note: in this case the ‘di’ does count for alphabetizing! 2. Priority for assigning root name: carboxylic acid > aldehyde > ketone > alcohol > amine > alkane For example, if you have a ketone and an alcohol functionality in the same molecule the root name would be derived from that of the ketone. Note: in class we did not discuss a suffix for ethers or alkyl halides – therefore these two functionalities are always named as branches on the alkane chain. If alcohol is part of molecule that contains a ketone or an aldehyde or a carboxylic acid then the alcohol is not the root name – instead it is called hydroxy and named as a branch. YOU WILL NOT BE GIVEN EXAMPLES WHERE AN AMINE IS IN THE SAME MOLECULE AS AN ALCOHOL, KETONE, ALDEHYDE OR CARBOXYLIC ACID. ALSO – YOU WILL NOT HAVE TO NAME COMPOUNDS WHERE THERE IS BOTH AN ALDEHYDE AND CARBOXYLIC ACID OR AN ALDEHYDE AND A KETONE OR A CARBOXYLIC ACID AND A KETONE IN THE SAME MOLECULE.

3. There is some confusion regarding nomenclature of amines. We only covered simple amines where there were no branches in the alkane chain – with this in mind, the nomenclature we discussed in class (ending “yl amine”) is what you should follow. See below for examples.

NH2

N

butylamine

butyldimethylamine...