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Functional Groups in Organic Chemistry

Jul 28, 2024

Notes on Functional Groups in Organic Chemistry

Introduction to Functional Groups

  • Discussion of unusual functional groups in addition to regular ones.

Hydrocarbons

Alkanes

  • Definition: Saturated hydrocarbons.
  • Example: Pentane - C5H12.

Cycloalkanes

  • Definition: Form a cyclic shape, unsaturated.
  • Example: Cyclopentane - C5H10.
  • Index of Hydrogen Deficiency (IHD): 1 (two hydrogen atoms less than pentane).

Bicycloalkanes

  • Definition: Compounds with two rings.
  • IHD: 2.

Unsaturated Hydrocarbons

Alkenes

  • Definition: Unsaturated hydrocarbons with at least one double bond.
  • IHD for each double bond: 1.

Dienes and Alkadienes

  • Definition: Molecules with two double bonds.
  • Conjugated Dienes: Alternating double-single bonds.
  • Accumulated Dienes: Double bonds adjacent to each other; also known as Allen.
  • Isolated Dienes: Dienes that aren't conjugated.

Alkynes

  • Definition: Hydrocarbons with triple bonds.
  • Terminology:
    • Internal alkyne: Triple bond in the middle.
    • Terminal alkyne: Triple bond at the end.
  • IHD: 2.

Aromatic Compounds

  • Definition: Compounds with an aromatic ring, e.g., benzene.
  • Example: Benzene - C6H6.
  • IHD: 4 (due to 3 double bonds in a ring).
  • Substituent Name: Phenyl in longer carbon chains.

Alcohols

  • Definition: Compounds with an -OH group.
  • Classification:
    • Primary Alcohol: OH on a primary carbon (attached to one carbon atom).
    • Secondary Alcohol: OH on a secondary carbon.
    • Tertiary Alcohol: OH on a tertiary carbon.

Diols

  • Definition: Compounds with two hydroxyl groups.
  • Example: CIS diol.

Other Functional Groups

  • Thiol: Compounds with sulfur; similar to alcohols.
  • Alkoxide: Conjugate base of alcohol.
  • Ethers: R-O-R,
  • Organic Peroxides: R-O-O-R; highly reactive.
  • Disulfides: Compounds with two sulfur atoms.

Cyclic Compounds

  • Epoxides: Three-membered ring with oxygen.
  • Dioxanes: Four-membered rings with two oxygen atoms.
  • Crown Ethers: Cyclic compounds useful for ion solvation (e.g., 12-crown-4, 15-crown-5).

Carbonyl Containing Compounds

Aldehydes and Ketones

  • Aldehyde: RCHO (one R group).
  • Ketone: R2CO (two R groups).
  • Example: Alpha-beta unsaturated aldehyde.
  • Aldehydes and ketones can have double bonds and still be identified based on functional groups.

Special Types

  • Thioalcohols and Thio ketones: Replace oxygen with sulfur.
  • Sulfoxides and Sulfones: Other derivatives of sulfur containing compounds.

Other Functional Classes

Carboxylic Acids

  • Definition: Contain COOH.
  • Can have halides or hydroxy groups replaced.
  • Amino Acids: Combination of carboxylic acid and amine functional groups.

Esters

  • Definition: Contains COO; cyclic versions are called lactones.

Amides and Lactams

  • Definition: Formed from carboxylic acids and amines.
  • Cyclic amides are known as lactams.

Conclusion

  • Covers a wide variety of functional groups and their properties within organic chemistry, focusing on classification, naming, and general reactivity associated with each group.

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