cycloalkane naming

cycloalkane naming - Dear Class, Naming compounds is...

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Unformatted text preview: Dear Class, Naming compounds is boring. On the test there will be nothing more difficult than what is in your book. Below you will find a succinct set of 3 rules that will help you with naming cycloalkanes. Rule number 2 is the most confusing so below I have given you a couple examples. Beyond this you can use a program called ChemDraw, which is on every chemistry department computer. Cycloalkane naming rules: 1. If two different substituents are on a ring they are listed in alphabetical order. The lowest alphabetic substituent is labeled as C1. The numbering of ring carbons then continues in a direction (clockwise or counter ­clockwise) that gives the second substituent the lower possible location number. 2. If several substituents are on a ring, they are listed in alphabetical order. Location numbers are assigned to the substituents so that one of them is C1 and the other locations have the lowest possible numbers, counting in either a clockwise or counter ­ clockwise direction. 3. The name is put together by listing groups in alphabetical order and giving each group (if there are two or more) a location number. The prefixes di, tri, tetra etc., used to designate several groups of the same kind, are not considered when alphabetizing. 4-ethyl-1-methyl-2-propylcyclohexane Lower numbers! Not see rule 2 above 1-ethyl-3-methyl-4-propylcyclohexane 1-ethyl-4-methyl-2-propylcyclohexane Not 2-ethyl-5-methyl-1-propylcyclohexane Lower numbers! see rule 2 above I accidently named this wrong in class. 4-ethyl-1,1-dimethylcyclohexane Not 1-ethyl-4,4-dimethylcyclohexane larger numbers. Rule 2! I also wanted to clarify that A and B below are the same compounds and hence will have the same IUPAC name. A B 1,3-dimethylcyclohexane 1,3-dimethylcyclohexane For A you number clockwise so that it is 1,3- not 1,5For B you number counter-clockwise so that you get 1,3- not 1,5 I have the habbit of just redrawing B as A so that I count clockwise. This is just my habbit, not required as long as you are following the numbering rules. All of these molecules are the same 1-ethyl-3-methylcyclohexane ...
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