CHEMISTRY 104 Help Sheet 2 Chapter 24 Part I Prepared by Dr Tony Jacob http www chem wisc edu areas clc Resource page Nuggets Drawing Naming Organic Molecules Functional Groups Part I NAMING MOLECULES 1 Find longest C chain 2 Number the longest C chain to give smallest numbers for functional group or side branches 3 Prefixes carbon atoms Meth 1 Eth 2 Prop 3 But 4 Pent 5 Hex 6 Hept 7 Oct 8 Non 9 Dec 10 4 Suffixes ane for alkanes ene for alkenes etc see below for other suffixes 5 a Branches add yl to prefix e g 1 C branch meth yl methyl 2 C branch eth yl ethyl etc b Duplicate branches di 2 tri 3 tetra 4 as in two 2 C branches diethyl c Alphabetize multiple branches do not alphabetize on the di tri or tetra ethyl before propyl ethyl before dimethyl alphabetize on the e and m ignore the di d Every branch must have a number carbon position associated with it every number has a branch e Commas between numbers dashes between numbers and letters 6 Alkene functional group check for cis trans isomers Example Name the molecule shown 1 Find longest C chain dashed rectangular box 7 carbons long prefix hept 2 All C C single bonds suffix ane 3 Find branches off chain dashed ovals One branch 1C long methyl two branches 2C long each is ethyl since two identical branches use diethyl 4 Number chain both ways choose numbering scheme to yield smaller numbers for branches bottom bold numbers Functional groups e g an alcohol get higher priority in numbering chain this molecule has no functional group 5 Alphabetize branches diethyl before methyl alphabetize on e and m 6 Each branch gets a number 2 methyl 3 4 diethyl 7 commas between numbers dashes between numbers and letters Name 3 4 diethyl 2 methylheptane 7 1 5 6 2 3 3 4 4 5 1 2 6 7 FUNCTIONAL GROUPS the first 7 C and H compounds hydrocarbons and O structures Functional Group Alkane Suffix ane Formula C C Alkene ene C C Alkyne yne C C Cyclic cyclo ane ene or yne Ex Aromatic benzene C 6H 6 Other Info saturated tetrahedral sp3 109 5 CnH2n 2 free rotation around C C bond unsaturated trigonal planar sp2 120 CnH2n geometric isomers cis trans can t rotate thru C C bond unsaturated linear sp 180 CnH2n 2 2 or Alcohol an ol R O H Ether ether R O R cycloalkane unsaturated strained tetrahedral sp3 CnH2n not planar planar molecule trigonal planar geometry at each C BOC C 1 5 sp2 120 resonance R H 1 primary 2 secondary 3 3 2 4 tertiary H bonding polar e g 3 methyl 2 butanol OH R R H polar alphabetize branches ether propyl e g methylpropylether methyl O 1 Alkanes only carbon carbon single bonds a sigma bond between C atoms saturated molecules formula CnH2n 2 often denoted as R C C bond can rotate Alkenes at least one carbon carbon double bond bonds formula CnH2n one double bond R R C C double bond can t rotate because of bond has cis and trans geometric isomers unsaturated molecule Alkynes at least one carbon carbon triple bond 2 bonds formula CnH2n 2 one triple bond R R C C triple bond can t rotate because of bonds unsaturated molecule Cyclic ring compounds formula CnH2n 1 ring 3 membered ring unstable 4 membered ring somewhat stable 5 membered ring stable and almost planar 6 membered ring stable puckered boat or chair configuration Aromatic for Chem 104 the focus is on benzene C6H6 or a derivative C C bonds equivalent BOC C 1 5 planar molecule naming omp ortho 1 2 disubstituted meta 1 3 disubstituted para 1 4 disubstituted Alcohol a OH hydroxyl group attached R OH H bonding primary 1 C with OH has 1 C atom attached secondary 2 C with OH has 2 C atoms attached tertiary 3 C with OH has 3 C atoms attached to it Ether bridging oxygen atom R O R R and R H otherwise it becomes an alcohol Hydrocarbons only hydrogen and carbon colorless nonpolar Properties C1 C4 gases C5 C17 liquids C18 higher solids Nonpolar immiscible doesn t mix in water found as a wide range of chain lengths fossil fuels longer chained fossil fuels made smaller by cracking branches added to molecules by reforming more branches allows for better combustion octane rating refers to a comparison to isooctane 2 2 4 trimethylpentane DRAWING MOLECULES H F Cl Br I 1 bond O usually 2 bonds N usually 3 bonds C 4 bonds Lewis all bonds and e drawn Expanded all bonds drawn Dash Wedge Condensed Structure Line Notation Variations Condensed Structures with some bonds drawn Cl H H C C H H H Cl H H H C C H H Cl C H H H C H H C H H Cl Cl H C C H H CH3CHCH3 CH3CHClCH3 Cl H CH3 CH CH3 1 Draw the following molecules in the Lewis dot format showing all bonds atoms and e and in line format a CH3CH2CH2CH2CH2CH3 b CH3 2CC CH3 2 c CHCCH3 2 Give the IUPAC name for each of the following molecules H a H H H H H H C C C C C C H H H H H H CH3 CH3 H CH2 CH2 CH CH3 CH3 b c CH3 CH3 CH C CH3 CH2 CH3 CH3 d g C C CH3 CH3 C CH3 CH2 f CH CH2 CH3 h CH3 CH2 CH3 CH2 CH CH2 CH2 CH3 CH3 e CH3 CH3 CH3 CH3 CH3 CH3 CH CH2 CH3 CH2 CH CH3 CH3 CH2 CH2 CH CH3 CH2 CH2 CH3 CH3 3 Using line notation draw the organic molecules given their names a 2 2 4 trimethylpentane b 1 1 2 trichlorohexane c 3 4 5 triethyl 2 6 dimethyloctane d 1 1 2 trichlorocyclopentane e 3 ethyl 4 methyl 2 pentanol f 1 ethyl 2 4 dimethylbenzene g ortho dichlorobenzene h 4 methyl 2 hexyne i 2 3 3 tribromo 1 butene j methylethylether k dipropylether 4 Give the IUPAC name for each of the following molecules a b c d e f g h i OH OH j k l 5 Which functional group could the molecule C35H70 contain a alkane b alkene c alkyne m n d alcohol e more info needed O 6 Draw the two resonance structures using line notation that are used to represent benzene C6H6 7 Which functional group is polar a cycloalkane b alkene c aromatic d ether e none are polar 8 Which functional group will have sp hybridization a cycloalkane b alkene c aromatic d ether e none will ANSWERS H 1 a H H H H H H C C C C C C H H H H H H H H H H H C H H H C C C C C H H H H C C C H H H H H b c 2 a hexane b 2 methylpentane c 2 4 5 trimethylheptane …