Unit 7.2 Nomenclature of Alcohols, Phenols & Ethers 🚀

Names tell the whole story in organic chemistry! 🎉 Follow these simple rules and you’ll breeze through NEET questions on alcohols, phenols, and ethers.:contentReference[oaicite:0]{index=0}

1. Alcohols (-OH on an sp3 carbon) 🥂

1 A. Common names

  • Write the alkyl group, then add the word alcohol.
    Example: \(\mathrm{CH_3OH}\) → methyl alcohol.

1 B. IUPAC names – five quick steps

  1. Select the longest chain that carries the –OH.
  2. Number the chain from the end nearest the –OH.
  3. Replace the terminal “-e” of the parent alkane with -ol.
    Example: \(\mathrm{CH_3CH_2CH_2OH}\) → propan-1-ol.
  4. Show the position (of –OH & other groups) with locants: 4-chloro-2,3-dimethylpentan-1-ol.
  5. For two or more –OH groups, keep the “-e” and add diol, triol …
    \(\mathrm{HO–CH_2–CH_2–OH}\) → ethane-1,2-diol (ethylene glycol).

1 C. Special cases

  • Cyclic alcohols: prefix cyclo-; the –OH is always at C-1.
    Examples: cyclohexanol, 2-methylcyclopentanol.
  • Primary, secondary, tertiary, allylic & benzylic categories still apply, but naming stays the same. 😊

2. Phenols (-OH on an aromatic ring) 🌸

  • The parent compound is simply phenol.
  • Use ortho- (o-), meta- (m-), para- (p-) in common names to show 1,2- / 1,3- / 1,4- patterns, but in IUPAC just give locants:
      o-cresol = 2-methylphenol.
      Catechol = benzene-1,2-diol.
      Resorcinol = benzene-1,3-diol.
      Hydroquinone = benzene-1,4-diol.
:contentReference[oaicite:1]{index=1}

3. Ethers (R-O-R′) 🎈

3 A. Common names

  • List the two groups in alphabetical order, then add ether.
    \(\mathrm{CH_3OC_2H_5}\) → ethyl methyl ether.
  • If both groups match, add the prefix di-: \(\mathrm{C_2H_5OC_2H_5}\) → diethyl ether.
  • “Simple/symmetrical” = same groups; “mixed/unsymmetrical” = different groups. 😉

3 B. IUPAC names

  1. Pick the larger group as the parent hydrocarbon.
  2. Name the smaller group + O– as an alkoxy substituent (\(-\mathrm{OR}\)).
  3. Give its position on the parent chain.
    Example: \(\mathrm{CH_3OCH_2CH_2CH_3}\) → 1-methoxypropane.
  4. For aromatic cases, attach the alkoxy to the ring: methoxybenzene (anisole).
:contentReference[oaicite:2]{index=2}
StructureIUPAC Name
\(\mathrm{CH_3OCH_3}\)methoxymethane
\(\mathrm{CH_3OCH(CH_3)_2}\)2-methoxypropane
\(\mathrm{C_6H_5OCH_2CH_2CH_2CH_2CH_2CH_3}\)1-phenoxyheptane
\(\mathrm{CH_3OCH_2CH_2OCH_3}\)1,2-dimethoxyethane

4. Practice Examples ✏️

  1. \(\mathrm{CH_3CH_2CH(OH)CH_3}\) → propan-2-ol
  2. \(\mathrm{HOCH_2CH_2CH_2CH_2OH}\) → butane-1,4-diol
  3. \(\mathrm{C_6H_5OH}\) → phenol
  4. \(\mathrm{C_6H_5OCH_3}\) → methoxybenzene
  5. \(\mathrm{ClCH_2CH_2CH_2OH}\) → 3-chloropropan-1-ol
:contentReference[oaicite:3]{index=3}

5. High-Yield Ideas for NEET 🎯

  • Pick the nearest carbon to –OH for numbering—this rule beats everything else!
  • For polyhydric alcohols, keep the “-e” of the parent and add diol/triol.
  • Alkoxy substituent naming in ethers is a favorite twist question.
  • Know ortho/meta/para positions on a benzene ring and their IUPAC equivalents (2-, 3-, 4-).
  • Spot the difference between sec-butyl and tert-butyl when converting common to IUPAC forms. 🔍

Keep practicing—nomenclature gets easier every time you write a name! 💪