Types of Chemical Reactions Quiz

Main Types of Reactions

• Addition: Atoms are added to a double or triple bond, breaking the bond.
• Alkene/Alkyne: Undergoes addition reactions to form single bonds.
• Substitution: A hydrogen atom or functional group is replaced by a different functional group.
• Elimination: Atoms are removed from a molecule to form double bonds. It is the reverse of an addition reaction.
• Oxidation: Carbon atom forms more bonds to Oxygen or fewer to Hydrogen. Example: formation of a C=O bond. It occurs in the presence of oxidizing agents like KMnO4, K2Cr2O7, O3.
• Reduction: Carbon atom forms fewer bonds to oxygen or more bonds to hydrogen.
• Condensation: Two molecules combine to form a single, bigger molecule, usually with the production of water.
• Hydrolysis: Water adds to a bond splitting it into two. It is the reverse of a condensation reaction.

Addition Reactions

• Reactants combined: Two reactants make one product.
• Common atoms added to alkenes or alkynes:
  • H and OH (from H2O)
  • H and X (from H-X) where X= Cl, Br, or I
  • X and X from (X2) where X= Cl, Br, or I
  • H and H (from H2)

Addition Reactions: Reactant - Process - Product

• Alkene + Hydrogen: Hydrogenation --> Alkane
• Alkene + Water: Hydration --> Alcohol
• Alkene + HF, HCl, HI, HBr: Hydrohalogenation --> Halogenated alkane
• Alkene + Halogen: Halogenation --> Double Halogenated alkane
• Alkyne + Hydrogen (limited amount): Hydrogenation --> Alkene
• Alkyne + Hydrogen (excess amount): Hydrogenation --> Alkane

Addition Reactions: Alkene

• Symmetrical molecules react with asymmetrical molecules to give one product.
• Asymmetrical molecules reactions yield a major and minor product.
• Markovnikov's Rule: The carbon atom with the largest number of carbon atoms gets the X (halogen) or OH bind to it.

Addition Reactions: Alkyne

• Follow Markovnikov's rule when asymmetrical.
• Can occur as two addition reactions.

Substitution Reaction

• Recognized by: Two compounds react to form two products.
• Examples:
  • Alkyl halide + ammonia → amine + HX
  • Ethanol + HI --> Iodoethane + H2O
  • Aromatic compounds can only undergo substitution reactions.
  • Halogens in HCl, HBr, or HI can substitute the OH group of alcohol, or the reverse.

Elimination Reaction

• Recognized by: One reactant breaks into two products.
• Alcohol: Undergo elimination when heated in the presence of a strong acid (H2SO4).
• Alkyl halides: Undergo elimination to produce alkenes.

Condensation Reactions

• Esterification: A carboxylic acid and alcohol can condense to form an ester.
• Amide Formation: A carboxylic acid and amine can condense to form an amide.

Hydrolysis Reactions

• Reverse of Condensation reactions: Water can add to an ester or amide bond.
• Ester + Water: Makes a carboxylic acid and alcohol.
• Amide + Water: Makes a carboxylic acid and amine.

Oxidation and Reduction Reactions

• Change in number of H or O atoms bonded to Carbon.
• Always occur together: One reactant is oxidized while the other is reduced.
• Focus on reactant only.

Oxidation

• Carbon atom forms more bonds to Oxygen or fewer to Hydrogen.
• Occurs in the presence of oxidizing agents like KMnO4, K2Cr2O7, O3.
• Alcohols: Oxidation can form an aldehyde or ketone.
  • Primary Alcohol --> Aldehyde
  • Secondary Alcohol --> Ketone
  • Tertiary Alcohols do not oxidize.
• Aldehyde: Undergo oxidation to produce carboxylic acid.

Reduction

• Carbon atom forms fewer bonds to Oxygen or more bonds to Hydrogen.
• Occurs in the presence of reducing agents such as LiAlH4, and H2 where Hydrogen [H] is added.
• Aldehyde, Ketone, Carboxylic acids: Can be reduced to become alcohols.
• Alkene and Alkyne: Can be reduced to become alkanes.

Combustion Reactions

• Not Balanced C.E.∆
• Occurs in the presence of oxygen (Unlimited)
• Produces CO2 and H2O (Limited)