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

to specify location and identity, respectively

# of Carbons Root name 1 Meth– 2 Eth– 3 Prop– 4 But– 5 Pent– 6 Hex– 7 Hept– 8 Oct– 9 Non–

10 Dec–

• alkyl group: alkane minus one H -- substituent

Name: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

3,3-dimethylhexane

C C

H

H

H

H

C

H

C

C

C

C

H

H

C

H

H

H

H

H

HHH

HHH

C C

H

H

H

H

C

H

C

C

C

C

H

H

C

H

H

H

H

H

HHH

HHH

Other Functional Groups:

• 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

the –OH the lowest number

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Carboxylic Acids: • contains –COOH (carboxy) group polar; form strong hydrogen bonds with each other and water • naming:

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

identity of any substituents

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

CH3CH2 CH2

CCH3

O

CH3CH

CH2COH

OCH3

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