The chemistry of carbon and carbon-based compounds Organic Chemistry The chemistry of carbon and carbon-based compounds

Why is carbon so special? Carbon is unique among the elements because: -- it can have up to four bonds per C atom  single, double, or triple bonds –C–C– C=C –C=C– -- it can form REALLY long chains of C atoms -- its bonds are strong

Organic Chemistry Organic Chemistry is everywhere! 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 3

Drawing Organic Structures Shortcuts make structures easier & faster to draw Butane: C4H10 Lewis Structure Carbon Atoms 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 Condensed Structures CH3CH2CH2CH3 CH3(CH2)2CH3

Practice Drawing Structures Formula Lewis Condensed Line C2H6 CH3CH3 C3H8 CH3CH2CH3 C5H12 CH3CH2CH2CH2CH3 or CH3(CH2)3CH3 C6H14 CH3CH2CH2CH2CH2CH3 or CH3(CH2)4CH3

Types of Organic Compounds Classified according to functional groups Alkane Alcohol Carboxylic acid Alkene Ether Amine Alkyne Ketone Amide Haloalkane Aldehyde Amino acid

Big Idea in Organic Chemistry Structure controls Function Each functional group has predictable reactivity

Naming Alkanes (or Paraffins) Made only of C and H All C atoms are tetrahedral (only C-C single bonds) General formula = CnH2n+2 (CH4, C2H6, C3H8, C4H10, etc.) Alkanes are named based on the number of carbons in the longest chain! 8

Naming Basic Alkanes Alkane Alkyl substituents # of C atoms 1 2 3 4 5 6 7 8 9 10 CH4 CH3CH3 CH3CH2CH3 CH3CH2CH2CH3 Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane -CH3 -CH2CH3 -CH2CH2CH3 Methyl Ethyl Propyl etc. Root: number of C atoms Suffix: functional group (-ane for alkanes) (-yl for alkyl groups)

Linear vs. Branched Alkanes General formula = CnH2n+2 (CH4, C2H6, C3H8, C4H10) Can have linear or branched alkanes C5H12 Same molecular formula, different structure: structural isomers Branches, including other atoms bonded, are called substituents. Common non-carbon ones are: –NO2 –NH2 –F –Br –I nitro amino fluoro bromo iodo

Naming Branched Alkanes (IUPAC) Octane 4-ethyl 6 2 8 4-ethyl-3,5-dimethyloctane 5 4 7 3 1 3-methyl and 5-methyl = 3,5-dimethyl Root name: name of longest continuous C chain (parent chain) Two equally long? Choose the one with more branches Number C atoms in chain, starting at end with first branch Identify substituents, give each a number (C it is connected to) Two or more identical substituents: use prefixes (di-, tri-, tetra-, etc.) List substituents alphabetically before root name Do not alphabetize prefixes Punctuation: commas separate numbers from each other hyphens separate numbers from names no space between last substituent & root name

Provide each counterpart. 1 2 5-ethyl-3-methyl octane 3 5 7 4 6 8 (C11H24) 4-ethyl-2-methylhexane (C9H20)

Naming Alkanes Practice a. 2,4-dimethylpentane b. 2,4-dimethylhexane c. 2,4,6-trimethylheptane d. 3-ethyl-2-methylpentane e. 2,3-dimethylpentane f. 2,2-dimethylhexane g. 2,5-dimethylhexane h. 4-methylheptane

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

Structural Isomer Practice On piece of your own paper, draw AND name ALL of the isomers for the following alkanes: Formulas # isomers C5H12 C6H14 C7H16 3 5 9 Some of your drawings may look different, but they are only different structures (isomers) if they also have different names If you complete that, try to draw and name all of the isomers for octane (C8H18) in your HW. There are 18 of them!

Structural Isomers: C5H12 pentane 2-methylbutane 2,2-dimethylpropane

Structural Isomers: C6H14 hexane 2,3-dimethylbutane 2-methylpentane 2,2-dimethylbutane 3-methylpentane

Structural Isomers: C7H16 heptane 2,2-dimethylpentane 2-methylhexane 2,3-dimethylpentane 3-methylhexane

Structural Isomers: C7H16 2,4-dimethylpentane 3-ethylpentane 3,3-dimethylpentane 2,2,3-trimethylbutane

Naming Practice Two equal numbering options? Number based on alpha order 1 2 3 4 5 6 1 2 3 4 5 6 5-chloro-2-fluorohexane 2-chloro-5-fluorohexane 2-chloro-4-fluoro-2,3-dimethylpentane 2-bromo-3-ethyl-4-iodopentane 2-bromo-4-chloro-3-isopropylpentane

Provide each counterpart. Br 3-bromo-2-chlorohexane Cl I 2-ethyl-1,1-diiodo heptane 2-methyl-1-nitrobutane NO2 NH2 NO2 2-amino-6-nitro-3-propyl heptane

Structural Isomers What are the possible structural isomers of C3H7Br? 1-bromopropane 2-bromopropane What are the possible structural isomers of C4H9Cl? 1-chlorobutane 2-chloro-2-methylpropane 2-chlorobutane 1-chloro-2-methylpropane

Cycloalkanes Alkanes with closed ring(s) of C atoms General formula: CnH2n (C3H6, C4H8, C5H10, etc.) Naming: use cyclo- prefix before alkane name cyclopropane n = 3 cyclobutane n = 4 cyclopentane n = 5 cyclohexane n = 6 C3H6 C4H8 C5H10 C6H12 Naming substituted cycloalkanes: 1 substituent: no numbering necessary 2 or more substituents: lowest numbering scheme, then by alpha 1-chloro-5-methylcyclohexane methylcyclopentane 1-chloro-3-methylcyclohexane

Fun Common Names broken windowpane boxane windowpane basketane

Teepane