Organic Nomenclature

Naming Carbon Based Molecules

Organic Nomenclature Tutorial

Organic Nomenclature Quizzes

Summary Chart of Organic Structures

Basics of naming an organic cmpd:

• Find the longest continuous carbon chain– This is the parent chain– Use a root prefix to indicate # of C’s

• Ex: meth, eth, prop, etc.

• Number the C’s from the end nearest the side groups– Side grps should be on lowest combination of C’s

• Name the side groups (alphabetical order if >1)• Number the side groups

– # corresponds to the C the side group is attached to

Root Prefixes for Organic Cmpds.Meth = 1 Oct = 8

Eth = 2 Non = 9

Prop = 3 Dec = 10

But = 4

Pent = 5

Hex = 6

Hept = 7

I. Saturated Hydrocarbon

1. Straight Chain HCa) n – root + ane

b)

c) Try this: CH3CH2

CH2

CH2

CH3

CH3CH2

CH2

CH3

2. Branched Chain HCa) # + side group + root + ane

b) Branch = if derived from alkane drop –ane and add –yl

n-pentane

n-butane

Alkyl Side Groups

Isopropyl-CH3 C CH3

H

Sec-butyl-

CH3 C CH3

CH3 Tert-butyl-(AKA: t-butyl)

Phenyl-

Methyl-

C

H

C

H

H

HH

Ethyl-

C

H

C

H

H

HH

C

H

H

Propyl-

C

H

H

H

CH3CH

CH3CH3

I. Saturated Hydrocarbon2. Branched Chain (cont’d)

c) Use di, tri, tetra, etc. to describe multiple side groups of the same kind (ex. triethyl-)

d) Arrange names of side groups in alphabetical order

2,2-dimethylbutane 2, 2, 3-trimethylpentane

CH3 C CH2

CH3CH3

CH3

CH3 C H2C

CH3CH3

CH3 CH2 CH3

Structural Isomers… • Same molecular formulas but different

arrangements of atoms (different structural formulas)

– Ex. butane and methyl propane are isomers

II. Unsaturated HC 1. Naming Alkenes – double bonds

a) # + side group + # + root + ene

b) Number chain so double bond gets lowest #

Try this:

Side groups: Root Chain: Location of bond:Family:

4-methyl-2-pentene

CH3

CH2CH3

CH3

4-methylPent-

2nd carbon-ene

Hint: # the C’s so the double bond gets lowest value

II. Unsaturated HC2. Naming Alkynes – triple bonds

a) # + side group + # + root + yne

b) Number chain so triple bond gets lowest #

Try this:

Side groups: Root Prefix: Location of bond:Family:

6-methylHept-

3-yne

6-methyl-3-heptyneCH3 H2C

CH2 C C

CH3

CH2

CH3

III. Cyclic Molecules *

• # + side group + Cyclo + root + family suffix– If side groups, number ring so side group gets

lowest #– If double bond, number it to get lowest #

• Try this:

Side groups: Root Chain: Family:

1-ethyl-2-methylCyclopent-

-ane

1-ethyl-2-methylcyclopentane

H2C

CH

CH2CH2

H2CCH3

CH3

Remember: These are listed alphabetically

Other Stuff

Substituent Name

-Br Bromo-

-F Fluro-

-Cl Chloro-

-I Iodo-

-NO2 Nitro-

-OH Hydroxy-(used if not

alcohol)

Other things that could be attached to chain:

Cis- and Trans-

cis-2-butene trans-2-butene

Name These:

Cis-3-hexenetrans-3-hexene

IV. Alcohols (R-OH) *1. # + side group + root + # + ol

2. -OH should get lowest number

3. See rules from I-III for additional info. Try This:

H2C

CH

CH2CH2

H2CCH3

OH

Side groups: Root Chain: Location of -OH:Family:

Cyclopentan-1

-ol

2-ethylcyclopentanol

2-ethyl

Can omit the 1 in the name. It is assumed to be on C #1 if no # listed.

IV. Alcohols (R-OH)Alternative Names:

2-ethylcyclopentanol

2-ethyl-1-cyclopentanol

2-ethylcyclopentan-1-ol

Draw: 2-ethyl-3-cyclopenten-1-ol

V. Aldehydes * -CHO 1. Root = longest C chain that contains

aldehyde group

2. Number C’s beginning at aldehyde group (this is always son C #1)

3. Aldehyde group requires no # in name

4. Root = ends in –al Ex. ethanal

5. Name side group according to previous rules

V. Aldehydes (examples)

Side groups: Root Chain: Family:

2-bromo-Hexan-

-al

2-bromohexanal

Side groups: Root Chain: Family:

3-hydroxy, 2-ethylButan-

-al

2-ethyl-3-hydroxybutanal

VI. Ketones * 1. Number C’s so keto group gets

lowest #2. Root = longest C chain w/keto group

on it3. Use # to indicate location of keto

group4. Root ending = -one5. Ex. propanone

VI. Ketones (examples)

Side groups: Root Chain: Location of Keto:Family:

3-methyl, 5-methylHeptan-

4-one

3, 5-dimethyl-4-heptanone

Side groups: Root Chain: Location of double bond:Location of Keto:Family:

N/Apenten-

3

-one2

Pent-3-en-2-one

VII. Carboxylic Acids* -COOH

1. Carboxy group always on C #1

2. Root = longest C chain w/carboxy group on end

3. Suffix = -oic acid

4. Ex. Ethanoic acid

VII. Carboxylic Acid (examples)Side groups: Root Chain: Location of double bond:Family:

N/AHexen-

2-oic acid

Cis-2-Hexenoic acid

Side groups: Root Prefix: Family:

N/AHexan-

-dioic acid

Hexanedioic acid

VIII. Ethers* R-O-R’1. General form of Name: alkyl alkyl ether

2. Examples:

side chain #1 Side chain #2

Dimethyl ether

Methyl propyl ether

Methyl isopropyl ether

IX. Esters* R-COO-R’ • Formed from dehydration rxn between alcohol

and carboxylic acid

(alcohol – ol + yl) (carboxylic acid –oic acid + oate)

• Example:

R1 R2 R1 R2C

O

+

O

COH OH +O H2O

carboxylic acid

alcoholester

methyl ethanoate

IX. Esters (examples)

Alcohol:Carboxylic Acid:

cyclohexanolethanoic acid

cyclohexylethanoate

2-heptanolAlcohol:Carboxylic Acid: butanoic acid

2-heptanylbutanoate

Alcohol acid

Alcohol acid

--yl--------ate

--yl--------ate

X. Amines * 1. Name each R group but change to –yl

ending (i.e. if R1 is CH3 group = methyl)

2. Name all side groups in alphabetical order

3. Followed by word “amine”• Ex. Ethyl methyl amine

4. If more than one side group is same, use di, tri, etc. to indicate how many

• Ex. diethyl amine

R1 N R2

R3

X. Amine (examples)R1:R2:R3:

cyclopentyl Cyclopentyl amine

ethylethyl Diethyl amine

methylethyl

Diethyl methyl amine

R1:R2:R3:

R1:R2:R3: ethyl