Organic analysis

• Test for alkenes

  Shake with bromine water

  if alkene present - orange -> colourless
• Testing for alcohols

  alcohol + carboxylic acid -> ester

  • if alcohol present -> ester made -> sweet smell made

  identifying an alcohol - use H+/Cr2O7^2- under reflux

  • primary & secondary alcohol - orange -> green
  • tertiary alcohol - stays orange (no observable reaction)
• Test for aldehydes

  Tollen's reagent

  if present -> silver mirror formed

  reagent gently oxidises aldehyde

  Fehling's reagent

  if present - blue -> brick red precipitate
• Test for ketones

  Tollen's reagent & Fehling's reagent

  if present -> no observable reaction
• Infrared Spectroscopy

  • Used to identify functional groups
  • bonds absorb different wavelengths of IR to move/flex atoms
  • have own unique natural frequencies
  • diff. bonds absorb diff. wavelengths but can only absorb IR with same frequency as its natural frequency
  • diff. bonds/functional groups absorb IR at different wavenumbers (unit cm^-1)
  • fingerprint region = below 1500cm^-1 in spectrum specific to the compound
• Test for halogenoalkanes

  1. Add NaOh(aq) & warm
  2. Acidify with HNO3
  3. Add with Ag2NO3(aq)

  A) Ag+(aq) + Cl- -> AgCl(s)

  B) white

  C) Ag+(aq) + Br- -> AgBr(s)

  D) Cream

  E) Ag+(aq) + I- -> AgI(s)

  F) Yellow