Chapter 23: Organic Chemistry Key topics: Nomenclature Functional groups Drawing skeletal structures Organic Chemistry o study of carbon-containing compounds o originally: compounds produced by living organisms o now: includes man-made compounds such as plastics Why Carbon is Different electron configuration: [He]2s 2 2p 2 o effectively prohibits ion formation (energetically VERY unfavorable to gain/lose 4 e – ) o fills octet by sharing e – Small atomic radius, n = 2 valence shell (no 2d orbitals) o short, strong bonds o good p orbital overlap to give π bonds o no 2d orbitals imparts stability (Si more reactive) o catenation to form chains and rings containing single, double and triple bonds
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Chapter 23: Organic Chemistry Key topics: Nomenclature Functional groups Drawing skeletal structures Organic Chemistry o study of carbon-containing compounds o originally: compounds produced by living organisms o now: includes man-made compounds such as plastics
Why Carbon is Different electron configuration: [He]2s22p2 o effectively prohibits ion formation
(energetically VERY unfavorable to gain/lose 4 e–) o fills octet by sharing e–
Small atomic radius, n = 2 valence shell (no 2d orbitals) o short, strong bonds o good p orbital overlap to give π bonds o no 2d orbitals imparts stability (Si more reactive) o catenation to form chains and rings containing single,
double and triple bonds
ethane: stable in water and air disilane: breaks down in water and spontaneously combusts in air
Classes of Organic Compounds Variety comes from o carbon forming chains by bonding to itself o presence of elements other than C and H o Functional groups – a group of atoms that determines
many of a molecule’s properties o multiple bonds
Alkanes: • contain C atoms connected by single bonds, and H atoms connected to C with single bonds Low density; totally insoluble in water • Naming: 1. Identify the longest continuous C chain to get the
parent name (root + “ane”) 2. Number the C’s in the continuous chain, beginning at
the end closest to the substituent (branch point) 3. Identify the substituent and use a number and a prefix
• functional groups determine chemistry that compound will undergo (electrostatic maps shown below)
Alcohols: • contains –OH group (hydroxyl group) Methanol, ethanol, and propyl alcohol are miscible with water • naming: 1. Identify the longest chain that includes the –OH group
2. Change the –e ending to -ol 3. Number to give the –OH the lowest number 4. When the chain also contains an alkyl substituent, give
1. Identify the longest chain that includes the carboxyl group
2. Change the –e ending to –oic acid 3. Number starting with the carbonyl (C=O) carbon 4. Use numbers and prefixes to indicate the position and
identity of any substituents
Esters: • contain –COO– group (between two other non-H groups) polar but cannot form strong hydrogen bonds • naming: -- Name as derivative of carboxylic acid by replacing the
–ic acid ending with –ate -- 1st part of name specifies the substituent that replaces the ionizable hydrogen of the corresponding acid Aldehydes: • contains –COH (carbonyl group) – at end of chain polar but cannot form strong hydrogen bonds with each other; however can form strong hydrogen bonds with water. • naming: 1. Identify the longest chain that includes the carbonyl
group 2. Change the –e ending to -al
3. Number starting with the carbonyl (C=O) carbon 4. Use numbers and prefixes to indicate the position and
identity of any substituents
Ketones: • contains –CO– (carbonyl group) -- between two other groups polar but cannot form strong hydrogen bonds with each other; however can form strong hydrogen bonds with water. • naming:
1. Identify the longest chain that includes the carbonyl group
2. Change the –e ending to -one 3. Number to give the carbonyl group the lowest possible
number 4. Use numbers and prefixes to indicate the position and
Primary Amines: • contains –NH2 group moderately polar; can form strong hydrogen bonds to each other and to water • naming:
1. Identify the longest chain that includes the –NH2 group 2. Change the –e ending to -amine 3. Number starting with the carbon to which the –NH2
group is bonded 4. Use numbers and prefixes to indicate the position and
identity of any substituents Primary Amides: • contains –CONH2 group (e.g. peptides) can form strong hydrogen bonds to each other; therefore amides have high melting and boiling points • naming:
1. Can be named as derivatives of carboxylic acids -- Or, by replacing the –e ending with –amide
Compounds with More than One Substituent: • Prefixes of di, tri, tetra, penta and so forth are used to
denote the number of substituents • Substituent names are alphabetized • Numbers are used to indicate position of the alphabetized
substituents • Prefixes are not counted when alphabetizing Representing Organic Molecules: • large numbers of ways to organize atoms in an organic
molecules: e.g. C5OHx
• Condensed structural formula (Condensed Structure): shows the same information as a structural formula but in condensed form
octane: C8H18 CH3(CH2)6CH3 molecular formula condensed structural formula
-- branches indicated using parentheses
2-methylheptane C8H18 CH3CH(CH3)(CH2)4CH3 Molecular formula condensed structural formula • Kekulé structures: similar to Lewis structure but without
showing lone pairs
• Skeletal Structures: Consist of straight lines that represent carbon-carbon bonds.
-- Heteroatoms (atoms other than C or H) shown explicitly