Nomenclature

• Naming steps:
  • Find longest carbon chain
  • Number the chain
    • Carbon 1 is closest to the highest-priority functional group
    • More oxidized = higher priority
  • Name substituents
  • Assign numbers to substituents
  • Complete the name

Alkanes

• Made of C–H groups
• Halogens are common substituents

Alkenes and Alkynes

• Alkenes: double bonds
• Alkynes: triple bonds
• Double bonds appear in unsaturated fatty acids

Alcohols

• Replace the “-e” at end of parent name with “-ol”
• Or use “hydroxy-” when it’s a substituent
• Common names: ethyl alcohol, isopropyl alcohol
• Two alcohol groups = diols or glycols

Diols

• Alcohols on same carbon = geminal diols
  • Spontaneously dehydrate to make carbonyl compounds
• Alcohols on adjacent carbons = vicinal diols

• Both contain carbonyl groups
• Aldehydes are at the end of the chain (chain-terminating)
• Ketones are in the middle of the chain

Aldehydes

• Carbonyl group at end of carbon chain, uses one carbon
• Replace “-e” with “-al”
• Methanal, ethanal, propanal = formaldehyde, acetaldehyde, propionaldehyde

Ketones

• Carbonyl in the middle of carbon chain
• Replace “-e” with “-one”
• Propanone = acetone
• If ketone is highest-priority group, give it the lowest possible number
• Can also name by listing alkyl groups in alphabetical order
  • Example: ethylmethylketone
• Acetone is the smallest ketone

Carbonyl substituent prefixes

• When used as substituents, use prefix “oxo-” (refers to carbonyl oxygen)
• Also see prefix “keto-”

Carbons relative to carbonyl

• Carbon adjacent to carbonyl carbon = alpha
• Next = beta, then gamma, then delta
• Applies on both sides of carbonyl

Carboxylic acids

• Contain both a carbonyl and hydroxyl group
• Usually occupy carbon 1 in the chain
• Most oxidized functional group; highest priority (only CO₂ is more oxidized)
• Use “-oic acid” instead of “-e”
• Methanoic acid = formic acid (methyl = form)
• Ethanoic acid = acetic acid
• Propanoic acid = propionic acid

Esters

• Carboxylic acid derivatives where hydroxyl group is replaced by an alkoxy group (–OR)
• “-oate” replaces “-oic acid”

Amides

• Hydroxyl group replaced with amino group
• Nitrogen can be bonded to 0, 1, or 2 alkyl groups
• “-oic acid” becomes “-amide”
• Substituents attached to nitrogen are labeled with N- and included as prefixes

Anhydrides

• Formed from 2 carboxylic acid molecules when a water molecule is removed
• Many are cyclic
• If symmetrical: replace “acid” with “anhydride”
• If not symmetrical: name both parent carboxylic acids, then add “anhydride”