New Release: Unit 14 Nomenclature Part B & Unit 15 Conjugation and Aromaticity are now available for purchase through the site. You can purchase the Semester 1 book for $40 at the Organic Chemistry Stores (W1-22) of the University of Alberta.

Nomenclature Can be Easy Points: IUPAC basics

Master organic chemistry nomenclature with Dr. B's expert guidance. Learn IUPAC basics and earn easy points on your exams.

Virtually every organic chemistry professor has at least some nomenclature questions on their exams. I’ve seen some exams with 25% nomenclature. Compared to many areas of organic chemistry, nomenclature can be easy points for a relatively small investment. The problem is that many professors barely cover it and some expect you to learn it on your own. I’m going to give you the basic rules in my next few posts. You can go to Unit 3 for more details, some excellent sample and practice problems.

Systematic nomenclature was formulated by the International Union of Pure and Applied Chemistry (IUPAC). Organic chemistry IUPAC nomenclature is based on the names of the straight-chain alkanes which you need to know by heart.   You will need to memorize the first few:  methane, ethane, propane and butane.  Starting with pentane you can know them by their obvious prefixes. Here’s a list of the first 10.

Almost all IUPAC rules for organic compounds are based on the rules for naming alkanes (next post.) Most alkanes are branched i.e. there is a parent chain with alkyl branches coming off of it. To make an alkyl groups, formally take off an H off the alkane and change the alkane name from -e to -yl. The alkyl group derived from taking any H from methane is called methyl. Likewise the ethyl group is derived from ethane. Propane has 2 different types of H. Removing any of the end H’s gives the propyl group. Removing one of the middle H’s gives the isopropyl group. We derive more groups in the Unit 3 but these few help us show how The Basic Rules works.

Next time we will talk about the basic IUPAC rules of alkane nomenclature which underpin practically all of organic chemistry nomenclature.

If you learn nomenclature so that you can ace that part of your exam go to Unit 3 of my Semester 1 book and Unit 14 of my Semester 2 book.

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