Naming Alkanes

Parent Chain Alkyl group Cycloalkane OUTCOME QUESTION(S): C11-5-14 NAMING AND DRAWING Name and draw structural models of simple and branched alkanes. Include: complete structural formula, molecular formula, general formula, isomers Name and draw structural models of simple and branched alkenes and alkynes. Compare and contrast the structure and uses of aromatic and aliphatic hydrocarbons. Vocabulary & Concepts Parent Chain Alkyl group Cycloalkane

International Union of Pure And Applied Chemistry Naming Alkanes Standard naming rules are set by the International Union of Pure and Applied Chemistry (IUPAC) The longest continuous carbon chain is the parent chain. Chains are named using prefixes for carbon number and a unique suffix for the compound type. Prefixes must be memorized - ane Eth 2 carbons single bonded C – C H Ethane IUPAC Naming International Union of Pure And Applied Chemistry

General formula – CnH2n+2 Alkanes Suffix ane General formula – CnH2n+2 Used to calculate the total carbons and hydrogens in the alkane Decane C10H22 What trends do you see? Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane CH4 CH3CH3 CH3CH2CH3 CH3CH2CH2CH3 CH3CH2CH2CH2CH3 CH3CH2CH2CH2CH2CH3 CH3CH2CH2CH2CH2CH2CH3 CH3CH2CH2CH2CH2CH2CH2CH3 C9H20 CnH2n+2 n = 10 2n+2 = 2(10)+2 = 22

Remember – 4 bonds for each carbon Drawing Alkanes Use line bonds to connect the correct carbon number in a “carbon skeleton.” Add hydrogen in the correct number for each carbon atom. 3 carbons single bonded Propane C3H8 Molecular Formula H H H Complete Structural Formula 2 3 H C – C – C H H 1 4 H H Remember – 4 bonds for each carbon

Condensed will be the most useful form for practicing Draw pentane: 5 carbons single bonded H H H H H Complete Structural Formula H C – C – C – C – C H 1 2 3 4 5 H H H H H Condensed Formula C – C – C – C – C H3 H2 H2 H2 H3 1 2 3 4 5 Condensed will be the most useful form for practicing C5H12 Molecular Formula (CnH2n+2)

This is a methyl group attached to a hexane parent chain Another alkane branched off the parent chain is called an Alkyl group (substituent). The alkyl branch follows the same naming system BUT ends in –yl to show that it is a substituent. C - C - C - C - C - C C 1 2 3 4 5 6 Branch Name –CH3 methyl –C2H5 or –CH2CH3 ethyl –C3H7 or –CH2CH2CH3 propyl This is a methyl group attached to a hexane parent chain

C C - C - C - C - C - C Naming Branched Alkanes Find the longest carbon chain (parent chain). Number the carbons in the parent from the end that gives the lowest number to the branch(es). For simplicity only a carbon skeleton is being used – don’t forget about the hydrogens Parent chain can be bent – as long as it is the longest continuous chain C - C - C - C - C - C C 1 6 5 2 3 4 3 4 2 5 1 6

C C - C - C - C - C - C Naming Branched Alkanes 3 - ethyl hexane Name each branch including the number of the parent carbon it is attached to (to show position). Name the parent chain. Hyphens separate position numbers from components 3 - ethyl hexane C - C - C - C - C - C C 1 2 Branch Name –CH3 methyl –C2H5 or –CH2CH3 ethyl –C3H7 or –CH2CH2CH3 propyl 3 4 5 6

Breakdown each piece of the name starting with the parent chain… Draw the structural formula for 2-methylhexane. Breakdown each piece of the name starting with the parent chain… C H3 C – C – C – C – C – C H3 H H2 H2 H2 H3 1 2 3 4 5 6 2-methylhexane

4-ethyl-2-methylhexane Use basic prefixes (di, tri) to show multiples of one type of alkyl group and parent numbers for each. The alkyls are named in alphabetical order Commas are used to separate numbers (eg. 3-ethyl-4,4-dimethylnonane) 4-ethyl-2-methylhexane 6 C C 5 C - C - C - C C - C - 4 3 2 1

5-ethyl-2,4-dimethyloctane Draw the carbon skeleton of 5-ethyl-2,4-dimethyloctane It doesn’t matter if the branch off an alkane goes up or down – have fun with it! C C C 4 C - C - C - C - C - C - C - C 1 2 3 5 6 7 8 C 5-ethyl-2,4-dimethyloctane

Draw a structural formula for 2,4-dimethylpentane C – C – C – C – C H3 H H2 H H3 1 2 3 4 5 2,4-dimethylpentane CH3CH(CH3)CH2CH(CH3)CH3 1 2 3 4 5 This is what it would look like as a condensed formula – brackets are used to indicate branches off the previous carbon

3-ethyl-2,7-dimethyl-4-propyloctane Draw: 3-ethyl-2,7-dimethyl-4-propyloctane Don’t get scared – break it down C H3 H2 C H3 H2 C – C – C – C – C – C – C – C H3 H H H H2 H2 H H3 1 2 3 4 5 6 7 8 C C H2 H3 H3 3-ethyl-2,7-dimethyl-4-propyloctane

Name the following: 2 1 3 4 5 6 7 8 3,3,5- trimethyl octane

If you can’t “see” the condensed – draw it out first… Take this condensed formula and name the compound. CH3CH2CH2CH(C2H5)CH2C(CH3)2CH3 7 6 5 4 3 2 1 If you can’t “see” the condensed – draw it out first… 7 6 5 4 3 2 1 4-ethyl-2,2-dimethylheptane

Any carbon in the circle can be #1 – so start at the branch CYCLOALKANES One more little thing… Same naming rules – but add prefix “cyclo” Name the carbon ring first, then number the carbons so as to give the alkyl groups the lowest set of numbers. C 4 1- methyl cyclo butane 1 3 2 1 C 6 2 Any carbon in the circle can be #1 – so start at the branch cyclo hexane 5 3 4

Name the following: 1,3- dimethyl cyclo pentane 1,2,3- trimethyl cyclo 5 2 C 4 1 3 1,2,3- trimethyl cyclo propane 2 1 Remember to count in the direction that gives the lowest numbers to the branches…

Parent Chain Alkyl group Cycloalkane CAN YOU / HAVE YOU? C11-5-14 NAMING AND DRAWING Name and draw structural models of simple and branched alkanes. Include: complete structural formula, molecular formula, general formula, isomers Name and draw structural models of simple and branched alkenes and alkynes. Compare and contrast the structure and uses of aromatic and aliphatic hydrocarbons. Vocabulary & Concepts Parent Chain Alkyl group Cycloalkane