Organic Chemistry: The chemistry of carbon and carbon-based compounds Organic Chemistry in everyday life: Smells & tastes: fruits, chocolate, fish, mint Medications: Aspirin, Tylenol, Decongestants, Sedatives Addictive substances: Caffeine, Nicotine, Alcohol, Narcotics Hormones/Neurotransmitters: Adrenaline, Epinephrine Food/Nutrients: Carbohydrates, Protein, Fat, Vitamins Genetics: DNA, RNA Consumer products: Plastics, Nylon, Rayon, Polyester

Butane: C 4 H 10 CH 3 CH 2 CH 2 CH 3 CH 3 (CH 2 ) 2 CH 3 Shortcuts make structures easier & faster to draw Line Structure Only shows bonds C atoms assumed at each end and intersection of bonds H atoms not shown Assume 4 bonds to each C Fulfill C’s 4 bonds by adding H’s Lewis Structure Condensed Structures Carbon Atoms

Classified according to functional group Alkane Alkene Alkyne Haloalkane Alcohol Ether Ketone Aldehyde Carboxylic acid Amine Amino acid Amide

Structure controls Function Each functional group has predictable reactivity

 All C atoms are tetrahedral and sp 3 hybridized (only C-C single bonds)  General formula = C n H 2n+2 (CH 4, C 2 H 6, C 3 H 8, C 4 H 10, etc.)  Can have linear or branched alkanes C 5 H 12 Same molecular formula, different structure: structural isomers Branches are called substituents Primary (1°) carbon atom:bound toone other C atom Secondary (2°) C atom:bound to2 other C atoms Tertiary (3°) C atom: ”3 ” Quaternary (4°) C atom: ”4 ” 3° 1° 2°

The fat dog shook himself, and then rolled over on the wet rug. The dog shook the fat rug, then rolled over and wet on himself. These two statements use the same words... but have very different meanings! OR Likewise, isomers may have the same formula, but have very different structures…

2-methylpropane or

 On piece of your own paper, draw AND name ALL of the isomers for the following alkanes: Formulas # isomers If you complete that, try to draw and name all of the isomers for octane (C 8 H 18 ). There are 18 of them! Some of your drawings may look different, but they are only different structures (isomers) if they also have different names Pentane Hexane Heptane C 5 H 12 C 6 H 14 C 7 H

pentane 2-methylbutane 2,2-dimethylpropane

hexane 2-methylpentane 3-methylpentane 2,3-dimethylbutane 2,2-dimethylbutane

heptane 2-methylhexane 3-methylhexane 2,2-dimethylpentane 2,3-dimethylpentane

2,4-dimethylpentane 3,3-dimethylpentane 3-ethylpentane 2,2,3-trimethylbutane

C 5 H 12 (Same formula, different structure) More branching → weaker London dispersion forces 36.0pentane methylbutane 9.52,2-dimethylpropane Boiling point (°C) Name Structure BP/MP of Linear alkanes > BP/MP of branched alkanes

Alkane Alkyl substituents # of C atoms CH 4 CH 3 CH 3 CH 2 CH 3 CH 3 CH 2 CH 2 CH 3 -CH 3 -CH 2 CH 3 -CH 2 CH 2 CH 3 Methyl Ethyl Propyl etc. Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane Root: number of C atoms Suffix: functional group (-ane for alkanes) (-yl for alkyl groups)

CH H H H Methane CH 4 H C CCC H H H H HHH H H Butane C 4 H 10 Butyl -C 4 H 9 Methyl -CH 3 CH H H ? R H C CCC H H H H HHH H ? Where R = any other C atom or arrangement of C atoms R

Name Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane CH 4 C 2 H 6 C 3 H 8 C 4 H 10 C 5 H 12 C 6 H 14 C 7 H 16 C 8 H 18 C 9 H 20 C 10 H 22 Number of Carbon Atoms Molecular Formula Melting Point, o C # of Isomers Boiling Point, o C

Compound Methane Ethane Propane Butane Pentane MW Boiling point (°C) Linear Alkanes: C atoms: gas at room temp C atoms: liquid at room temp >15 C atoms: solid at room temp Larger molecular weight → Stronger London dispersion forces Nonpolar → only London Dispersion Forces IMF Formula CH 4 C 2 H 6 C 3 H 8 C 4 H 10 C 5 H 12

Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 429

1. Root name: name of longest continuous C chain (parent chain) 2 equally long? Choose the one with more branches 2. Number C atoms in chain, starting at end with first branch 3. Identify substituents, give each a number (C it is connected to) Two or more identical substituents: use prefixes (di-, tri-, tetra-, etc.) 4. List substituents alphabetically before root name Do not alphabetize prefixes 5. Punctuation:commas separate numbers from each other hyphens separate numbers from names no space between last substituent & root name 4-ethyl-3,5-dimethyloctane ethyl 3-methyl and 5-methyl = 3,5-dimethyl Octane

isopropyl isobutyl sec-butyl tert-butyl alphabetized as “i” alphabetized as “b” R R R R R R R R Remember that R = any carbon chain “iso” indicates symmetry 3 carbons 4 carbons 2o2o 2o2o Secondary carbonTertiary carbon 3o3o 3o3o

H CH H H C CC H H HHH C H H H 2 - methylbutane butane Expanded StructureLine Structure

H C CCC H H CH 3 H H H C C H H H H H hexane 3,3-dimethyl hexane 4,4-dimethyl Lowest sum of numbers is correct Line Structure