Organic Chemistry

Brown, LeMay Ch 25

AP Chemistry

225.1: Organic Chemistry

The study of carbon compounds, but not limited to living systems Biochemistry: study of the chemistry of living

things

Functional group: a group of atoms which determine how a molecule functions or reacts A part of a molecule that is not part of the

“base” carbon chain Also called a substituent

325.2: Intro to Hydrocarbons Compounds composed of only C and H Combust to form CO2 and H2O

Types:1. Alkanes: contain only single C-C bonds

Also called saturated (contain the maximum # of H’s)

Unsaturated: contain < maximum # of H’s2. Alkenes: contain at least one C=C bond3. Alkynes: contain at least one C≡C bond4. Aromatics: C’s connected in a planar ring (contain

and bonds) and have delocalization

425.3: AlkanesLewis structure vs. condensed structural

formula

Ex: C4H10

H3C–CH2–CH2–CH3

CH3CH2CH2CH3

5Structural isomers

Compounds with same formula but different structures (different bonding arrangements) Free rotation around C-C bonds limits number of

isomers of alkanes * Straight-chain

n- all C in a continuous chain

* Branched

iso- one CH3 branched off

t- or neo- lower-case “t”-shaped

6Ex: Draw all the structural isomers for...

CH4 C2H6

C3H8

C4H10

C5H12

7Organic Nomenclature

Originally formulated by IUPAC in 1892(http://www.acdlabs.com/iupac/nomenclature/)

1. Find the longest continuous chain of C atoms; use the name of this chain as the base of the compound’s name.

1 = meth- 2 = eth- 3 = prop- 4 = but- 5 = pent-6 = hex- 7 = hept- 8 = oct- 9 = non- 10 = dec-

prefix base suffix

What substituents?How many carbons?

What “family”?

82. Number the C atoms in the longest chain,

beginning with the end nearest to a substituent. If different substituents are present, give the lowest number to the substituent with highest priority (see list).(http://www.chem.ucalgary.ca/courses/351/Carey5th/nomenclature/functional/func.html)

3. Name and give the location (carbon #) of each substituent as prefixes or suffixes. (It varies.)

4. When 2 or more substituents are present, name them in alphabetical order as prefixes

When 2 or more of the same substituents are present, use a Greek prefix (di-, tri-, tetra-, penta-, hexa-, …)

9Ex: Name all the molecules.

CH4 C2H6

C3H8

C4H10

C5H12

methane ethane

propane

butane

2-methylpropane

2,2-dimethylpropane

pentane

2-methylbutane

10

Saturated hydrocarbons Alkanes: CnH2n+2; suffix is -ane

Cycloalkanes: CnH2n (n>2); prefix is cyclo- C’s bonded in a ring; not planar like an aromatic

compound (except cyclopropane)

Ex: Draw Lewis structures of the first 4 cycloalkanes and name them.

cyclopropanecyclobutane

cyclopentane

cyclohexane

1125.4: Unsaturated hydrocarbons

Alkenes: CnH2n; prefix is bond #; suffix is –ene

(more than one double bond: –diene, -triene) Geometrical isomers: same formula & same groups,

but different structures.

cis- groups with highest priority on same side of

bond axis (high priority = high atomic mass)

trans- groups with highest priority diagonal/across the

double bond

Ex: Draw and name all the isomers of C4H8.

x

y

x

y

12

Alkynes: CnH2n-2; prefix is bond #; suffix is–yne Reactions: unsaturated molecules are more

chemically reactive than saturated compounds

Addition: H3C-C≡C-CH3 + Br2 → ?

Hydrogenation:

CH3-CH=CH-CH3 + H2 → ?

Br―Br → H3C-C=C-CH3|Br

|Br

H―H→ H3C-CH―CH-CH3

|H

|H

13

Aromatics: named like alkanes, but primarily based on benzene Prefix describes relative positions of

substituents:ortho- 2 substituents next to each othermeta- 2 substituents separated by one Cpara- 2 substituents separated by two C’s

ortho- meta- para-

Naphthalene: “mothballs”

14

25.4 – 25.5: Functional GroupsNotation:“R” stands for:

Alkyl group, such as-CH3

-C2H5

-C3H7, etc.

H

Name of group

Formula of group

Suffix Name

Example structure

Example chemical

name

Carboxylic acid

O ||

R-C-OH

or

“R-COOH”

-oic acid

Ester

O ||

R-C-O-R

or

“R-COOR”

-yl ___oate

Aldehyde

O

||

R-C-H

or

“R-CHO”

-al

KetoneO

||

R-C-R

-one

Alcohol

R-O-H

or

“R-OH”

-ol (suffix if highest priority)

hydroxyl- (prefix if

lower priority)

Ether R-C-O-C-R ___ ether

Amine R-NH2 -amineNH2

NH2

Alkene \ / C=C / \

-ene

Alkyne R-C≡C-R -yne

Halide R-X

halo-

(bromo-, chloro-, fluoro-, iodo-)

Cycloalkane C ringcyclo-

___-ane

Cycloalkene

C ring with

double bond(s)

cyclo-___-ene

Alkane-(CH2)n-

CH3

-yl

20

*25.7: Chirality Chiral: a molecule having a

nonsuperimposable mirror image(Originally discovered by Louis Pasteur) Compounds containing C atoms with four

different substituents are inherently chiral

Optical isomers or enantiomers: nonsuperimposable mirror images

Labeled “L” (levo, left-handed) and “D” (dextro, right-handed)

Racemic: a mixture containing both enantiomers (both L and D)

http://nobelprize.org/educational_games/chemistry/chiral/