Naming Organic Compounds Today’s Objectives: Name and draw structural, condensed structural, and line diagrams and formulas for saturated and unsaturated aliphatic (including cyclic) Containing up to 10 carbon atoms in the parent chain/cyclic structure Containing only one type of a functional group or multiple bond Using the IUPAC nomenclature guidelines Identify types of compounds from the functional groups, given the structural formula Define structural isomerism and relate to variations in properties Section 9.2 (pg. 366-374)

Four Types of Formulas Molecular Formulas C5H10(g) Not very useful for organic compounds because so many isomers can exist Structural Formulas 3. Condensed Structural Formulas 4. Line Diagrams – end of line segment represents carbon – it is assumed to satisfy each carbon’s octet

Naming Organic Compounds Aliphatic Hydrocarbons – contains only hydrogen and carbon atoms Straight line chains of carbon atoms Alicyclic hydrocarbons have carbon atoms forming a closed ring. Still considered aliphatic Saturated hydrocarbons - compounds of carbon and hydrogen containing only carbon–carbon single bonds with the maximum number of hydrogen atoms bound to each carbon. Alkanes Alkenes Alkynes Only single C-C bonds Double C-C Bond present Triple C-C bond present General formula CnH2n+2 General formula: CnH2n CnH2n-2 Saturated Unsaturated

Naming Organic Compounds In organic chemistry, names have a root and a suffix. The root describes the number of carbons present in the chain or ring. The suffix describes the type of compound it is.

Naming Organic Compounds

Naming ALKANES Find the parent chain (the longest continuous chain of carbon atoms). Use the appropriate root and the suffix-ane.

Naming ALKANES Find the parent chain. Use the appropriate root and suffix. Number the carbon atoms, starting from the end closest to the branch(es) so that the numbers are the lowest possible Identify any branches and their location number on the parent chain (us the suffix –yl for branches) Write the complete IUPAC name, following the format: (number of location, if necessary) – (branch name) (parent chain) 2-methylheptane

Naming ALKANES If more than one of the same branch exist, use a multiplier to show this (di, tri). Remember to include all numbers Draw 2,4,6-trimethylheptane

ethyl before methyl (e before m in the alphabet) Naming ALKANES If different branches exist, name them in alphabetical order ethyl before methyl (e before m in the alphabet)

Naming ALKANES If there is more than one branch of the same type, a locating number is given to each branch and a prefix indicating the number of that type of branch is attached to the name. This numbering prefix does not affect the alphabetical order of the branches Draw the structural formula for 3,4-dimethylhexane

Summary of Naming Alkanes Find the parent chain. Use the appropriate root and suffix. Number the parent chain carbon atoms, starting from the end closest to the branch(es) so that the numbers are the lowest possible Identify any branches and their location number on the parent chain (us the suffix –yl for branches) If more than one of the same branch exist, use a multiplier (di, tri) to show this. Remember to include all numbers If different branches exist, name them in alphabetical order Separate numbers from numbers using commas, and numbers from words using dashes (no extra spaces)

Don’t forget Questions will specifically ask about structural, condensed structural or line structural formulas. You must be comfortable drawing any of the three

Practice Write the IUPAC name for the following 2,5-dimethyl-4-propyloctane

Correct the following names: 4-ethyl-2-methylpentane ACTUALLY 2,4-dimethylhexane ALWAYS LOOK FOR LONGEST CHAIN!!

Correct the following name: 4,5-dimethylhexane Actually 2,3-dimethylhexane **Want branch numbers to be as low as possible

CYCLOALKANES Based on evidence, chemists believe that organic carbon compounds sometimes take the form of cyclic hydrocarbons: Cycloalkanes: Alkanes that form a closed ring General Formula CnH2n Two less hydrogens are present than in straight chain alkanes because the two ends of the molecule are joined Are these considered saturated?? Yes, because they have only single bonds and the max amount of hydrogen's bonded to the carbons Cyclo-compounds will have a higher boiling point than their straight chain partners (because there is an additional bond present)

Naming CYCLOALKANES Cycloalkanes are named by placing the prefix cyclo in front of the alkane name, as in cyclopropane and cyclobutane If branches are present, treat the cycloalkane as the parent chain and identify the branches. Since there is no end at which to start the numbering, use the lowest numbers possible

Name the following: 1. 2. 1,2-dimethylcyclopentane ethylcyclohexane 1. 2. 1,2-dimethylcyclopentane ethylcyclohexane **Why don’t we need a number?

Today’s homework Pg. 370 #7 (a-c) ,9, 10 (a-b) 11 (a-c) Pg. 372 #5-6 Due tomorrow(1st day back) /21 pts What is coming up tomorrow? Naming Alkenes, Alkynes, Cycloalkenes and Cycloalkynes Comparing properties of Isomers