Chapter 20 Hydrocarbon Compounds Organic naming
Hydrocarbons contain only two elements: hydrogen and carbon Carbon has 4 valence electrons, thus forms 4 covalent bonds – not only with other elements, but also forms bonds WITH ITSELF.
Names recommended by IUPAC - the International Union of Pure and Applied Chemistry
Prefixes for carbon meth - one eth - two prop- three but- four penta- five hexa- six hepta- seven octa- eight nano- nine deca- ten
Alkanes Single bonded carbon C-C-C C-C-C-C etc. Formula: C n H 2n + 2
Alkanes Many alkanes used for fuels: methane, propane, butane, octane – The first 4 are gases; #5-10 are liquids; higher alkanes are solids
Alkenes Hydrocarbons containing carbon to carbon double bonds are called alkenes C=C C-C=C Called “ unsaturated ” if they contain double or triple bonds Formula: C n H 2n
Alkynes Hydrocarbons containing carbon to carbon triple bonds called alkynes -C C- Alkynes are not plentiful in nature Formula: C n H 2n - 2
Name the following: C C HH HH HH
Name the following: CC HH HH CH H H H
CC HH HH CH H H C H H C H H H
CC HH HH CHC C H H H
CC H HH CH H C H H C H H H
Branched-Chain Alkanes Branched-chain means that other elements besides hydrogen may be attached to the carbon – Halogens (bromine becomes bromo, fluorine becomes fluoro), oxygen, nitrogen, sulfur, etc. – Position of these elements are in the name
Branched-Chain Alkanes A hydrocarbon substituent is called an alkyl group – use the same prefixes to indicate the number of carbons, but the -ane ending is now -yl – -CH 3 methyl, – -CH 2 CH 3 ethyl, – -CH 2 CH 2 CH 3 propyl, etc.
Branched-Chain Alkanes Rules for naming 1. Longest chain is parent 2. Number, so that the branches have the lowest # 3. Give position number to branch 4. Prefix more than one branch 5. Alphabetize branches 6. Use proper punctuation ( -, )
From the name, draw the structure: 1. Find the parent, with the -ane 2. Number carbons on parent 3. Identify substituent groups; attach 4. Add remaining hydrogens
3-ethylpentane 2,3,4-trimethylhexane Pentene