Organic Chemical Reactions Quiz

Organic Chemical Reactions

• Cracking is breaking down large hydrocarbon molecules into smaller, more useful ones.
• Important in petrochemistry to convert long-chain hydrocarbons from crude oil into shorter-chain ones (alkanes and alkenes).
• Two main types:
  • Thermal Cracking: High temperatures (450°C-750°C) and pressures (up to 70 atmospheres) break carbon-carbon bonds, generating free radicals, and leading to a mixture of products including alkenes.
  • Catalytic Cracking: Uses a catalyst (like zeolite) at lower temperatures (around 500°C) and moderate pressures to improve reaction efficiency by lowering activation energy, breaking C-C bonds and rearranging molecules, leading to higher yields of desirable products like gasoline.

Addition Reactions

• Limited to compounds with multiple bonds (like alkenes and alkynes) and ring structures.
• Involves adding atoms or groups to the carbon atoms of a multiple bond (or a ring).
• One example is hydrogenation, where hydrogen is added to the multiple bond.

Elimination Reactions

• Opposite of addition.
• At least one H⁺ is lost to form a double bond.
• Same mechanism as dehydration or oxidation.
• A reversed reaction of Addition.

Substitution Reactions

• Also known as single displacement reactions.
• A functional group in a chemical compound is replaced by another functional group.
• One functional group in a chemical compound is substituted with another.

Cyclization Reactions

• Involve the formation of cyclic compounds from acyclic precursors.
• Can occur through various mechanisms, including nucleophilic attacks and rearrangements.
• Cyclization typically occurs when functional groups in a linear molecule react with each other to form new bonds, creating a ring structure.

Oxidation

• A carbon atom in an organic compound loses a bond to hydrogen and gains a new bond to a heteroatom (or another carbon), this is signified as dehydrogenation.
• Common biochemical example: oxidation of alcohol to ketone or aldehyde.
• The loss of hydrogen atoms from an organic compound.

Reduction

• Opposite of oxidation.
• A carbon atom gains a bond to hydrogen and loses a bond to a heteroatom (or another carbon).
• Same mechanism as Addition.
• Represents the gain of hydrogen atoms to an organic compound. Example: Hydrogenation of an alkene to an alkane.

Condensation Reactions

• Two molecules combine to form a single molecule and a small molecule, often water, is removed.
• Important in biological molecules. Bond forms between amine and carboxyl groups, which are part of amino acids.
• Formation of peptide bonds between amino acids.

Esterification

• Formation of an ester molecule from a carboxylic acid and an alcohol with an acid catalyst.
• Water molecule removed in the process.

Hydrolysis

• A reverse reaction of esterification.
• Organic compounds react with water to form different products.
• Depends on concentrations of protons or hydroxide ions.
• Described by classic concepts of substitution or addition by HO- or H2O to sp³ or sp² carbon atoms.

Polymerization (Synthesis)

• Reacting monomer molecules together to form polymer chains.
• Example: Ethene monomers react to form polyethylene.

Test your knowledge on organic chemical reactions, focusing on cracking and addition reactions. This quiz covers key concepts such as thermal and catalytic cracking, and the process of hydrogenation. Ideal for students of organic chemistry looking to master these essential reactions.