[11.2] nomenclature

Question 1

how to name organic molecules

Answer 1

1. find and name the longest continuous carbon chain (eg. 4 carbons = butane)
   - if there is a functional group it must be in the longest C chain
   - alkyl groups (eg. methyl, ethyl) are not functional groups
2. number the longest C chain (that contains the functional group) from the end that gives the functional group(s) the lowest number
   - include numbers in the name when they are necessary but omit them in simple molecules where it is obvious that no numbers are needed
3. put groups on the chain in the name
   - groups that come off the C chain are given a number to show which C atom they are on
   - when writing the name, list the groups in alphabetical order
   - if there are several groups that are the same, add the prefix di/tri/tetra/etc (which is ignored when working out alphabetical order)

> numbers are separated by commas
numbers and letters are separated by dashes

Question 2

number of carbon in the chain and the stem for that name (C1-10)

Answer 2

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

Question 3

alkanes

Answer 3

• suffix: ane
• example: propane

Question 4

alkenes

Answer 4

• function group: C=C
• suffix: ene
• example: but-2-ene

Question 5

halogenalkanes

Answer 5

• function group: -F, -Br, -Cl, or -I
• prefix: fluoro / chloro / bromo / iodo
• example: 2-bromopropane

Question 6

alcohols

Answer 6

• functional group: -O-H
• prefix: hydroxy (only used if suffix cannot be used)
• suffix: ol
• example: propan-1-ol

Question 7

aldehydes

Answer 7

• functional group: -C-H with =O on top of C
• suffix: al
• example: propanal
• the C atom in this functional group is defined as carbon-1 in the chain

Question 8

ketones

Answer 8

• functional group: C with =O on top
• prefix: oxo (only used if suffix cannot be used)
• suffix: one
• example: butanone

Question 9

carboxylic acids

Answer 9

• functional group: -C-O-H with =O on top of C
• suffix: oic acid
• example: ethanoic acid
• the C in the carbon atom in this functional group id defined as carbon-1 in the chain

Question 10

amines

Answer 10

• functional group: -N-H with -H on top of N
• prefix: amino
• suffix: amine
• example: ethanamine

Question 11

acid anhydrides

Answer 11

• functional group: -C-O-C- with =O on top of Cs
• suffix: oic anhydride
• example: ethanoic anhydride
• molecules are symmetrical so count from central O outwards

Question 12

esters

Answer 12

• functional group: -C-O- with =O on top of C
• suffix: oate
• example: methyl propanoate

Question 13

amides

Answer 13

• functional group: -C-N-H with =O on top of C and -H on top of N
• suffix: amide
• example: ethanamide

Question 14

cyclic compounds

Answer 14

• cyclic alkane with no other functional groups = cyclopentane (eg.)
• if there are functional groups that need to be numbered, do so according to which one gives the lowest number
• if there is only one functional group it does not need a number

Question 15

what is the order of priorities for different functional groups?

Answer 15

• carboxylic acid
• nitrile
• aldehyde
• ketone
• alcohol
• amine
• alkene
• halogenalkane

Question 16

how does the order of priorities affect the naming/numbering?

Answer 16

• highest priority groups take the lowest number in the C chaine
• if there are two groups that have suffixes, then the lower priority group becomes a prefix
• eg. 4-oxopentanal