LAB LAB LAB

• Hydrocarbons


  The simplest organic compounds that contain only carbon and hydrogen
• Hydrocarbons


  • Can be open chain (aliphatic) or closed chain (cyclic)
  • Can be saturated or unsaturated
• Saturated hydrocarbons


  Characterized by the presence of only sigma (σ) bonds; the carbon atoms are all single-bonded
• Unsaturated hydrocarbons


  Include alkenes (C=C) which contain at least one pi bond (π) as well as alkynes, cycloalkenes, cycloalkanes and aromatic compounds (contains benzene ring)
• Saturated hydrocarbons are generally inert towards HCl and H2SO4, as well as towards oxidizing agents like KMnO4 and Na2Cr2O7 at room temperature
• Saturated hydrocarbons are nonpolar compounds and do not react with ionic compounds such as laboratory acids, bases, oxidizing agents or reducing agents
• Saturated hydrocarbons react with Halogens (Br2 or Cl2) to yield halogenated alkanes under the presence of UV light or at very high temperature
• Addition reaction


  The characteristic reaction of unsaturated hydrocarbons that takes place at the double bond
• Substitution reaction


  The characteristic reaction of saturated hydrocarbons with Halogens (Br2 or Cl2) to yield halogenated alkanes
• Aromatic compounds


  • Exhibit resonance that results in conjugative stability of the molecule
  • Resist addition to the pi bonds but readily undergo substitution
• Phenols


  Compounds in which a hydroxyl group is bonded to an aromatic ring
• Phenol is a weak acid, it gives red color with litmus paper
• Bromine water test for unsaturation

  Alkenes and alkynes decolorize the bromine water due to their ability to undergo addition reactions with bromine, which breaks the pi bond in the unsaturated compound
• Baeyer's test for unsaturation

  Double bonds in alkenes are oxidized by KMnO4, leading to the formation of diols (1,2-diols) or cleavage of the double bond in the presence of a triple bond (alkyne)
• Electrophilic Aromatic Substitution (EAS)


  Involves an electrophile substituting for an atom or group in an aromatic ring
• Alcohols


  Compounds containing the hydroxyl (-OH) functional group bonded to an alkyl, R
• Chromic acid test for alcohols

  Primary or secondary alcohols undergo oxidation to form an aldehyde or ketone, while tertiary alcohols do not react
• Lucas test for alcohols


  Tertiary alcohols react immediately with Lucas reagent to form a cloudy solution, secondary alcohols react within minutes to hours, while primary alcohols do not react at room temperature
• Esterification test for alcohols

  The alcohol is mixed with a carboxylic acid and heated under reflux with the acid catalyst, producing an ester and water
• Iodoform test for alcohols

  The compound is treated with iodine in a basic solution, forming a yellow precipitate of iodoform (CHI3) if a methyl ketone or alcohol is present
• Acrolein test for alcohols

  The alcohol is heated with potassium bisulfate (KHSO4) or chromic acid (H2CrO4) under acidic conditions, forming acrolein which can be recognized by its pungent smell and irritating fumes
• Carbonyl group


  The general formula of an aldehyde is R(C=O)H, while a ketone is represented by the formula R(C=O)R
• 2,4-Dinitrophenylhydrazine test for carbonyl group


  Interacts with the carbonyl group found in aldehydes and ketones, producing a yellow or orange precipitate of 2,4-Dinitrophenylhydrazone
• Sodium bisulfite test for carbonyl group

  Produces a white precipitate, confirming the existence of the carbonyl group
• Schiff's test for aldehydes


  Schiff's reagent produces a distinctive pink or magenta hue with an aldehyde
• Carbonyl group


  Found in aldehydes and ketones
• 2,4-Dinitrophenylhydrazine test


  1. Interacts with carbonyl group

  2. Produces yellow or orange precipitate of 2,4-Dinitrophenylhydrazone
• Positive 2,4-Dinitrophenylhydrazine test


  • Acetone
  • Acetophenone
  • Benzaldehyde
  • Formalin
• Sodium Bisulfite test


  1. Produces white precipitate

  2. Confirms existence of carbonyl group

  3. Aldehyde reacts with sodium bisulfite to form white crystalline compound
• Aldehydes


  Have hydrogen atom next to carbonyl group
• Schiff's test


  1. Schiff's reagent produces pink or magenta hue with aldehydes

  2. Determines presence of aldehydes
• Positive Schiff's test


  • Benzaldehyde
  • Formalin
• Negative Schiff's test


  • Acetone
  • Acetophenone
• Fehling's test


  1. Aldehyde reduces copper(II) ions to red copper(I) oxide precipitate

  2. Indicates presence of aldehydes prone to oxidation
• Positive Fehling's test


  • Formalin
  • 5% glucose
• Negative Fehling's test


  • Acetone
  • Benzaldehyde
• Sodium Nitroprusside test


  Produces deep red-to-purple color complex with some ketones, particularly those containing a methyl group adjacent to carbonyl group
• Positive Sodium Nitroprusside test

  • Acetone
  • Ethyl methyl ketone
• Iodoform test


  Gives yellow iodoform precipitate with methyl ketones
• Positive Iodoform test


  • Acetone
  • Methyl ketone