TChem_Chapter_12__Putting_it_all_Together

Chapter 12: Putting it all Together

• Overview of chemical reactions and their components.

Chapter 12 To-Do’s

• Describe the components of a chemical reaction:

  • Reactants, Catalysts, Products.

• Describe the steps of a chemical reaction:

  • Transition States, Intermediates.

• Define "Reaction Sequence."

• Compare/Contrast oxidation vs. reduction.

• Review and assign oxidation numbers.

• Compare/Contrast oxidation of:

  • Ethanol vs. Methanol.

• Compare/Contrast:

  • Nucleophile vs. Electrophile.

• Identify common players in the embalming process for each.

• Briefly describe the reaction of formaldehyde with an amine.

• Explain the role of the methylene bridge in embalming.

• Describe hydrolysis.

The Chemical Reaction

• Definition: Transformation of one chemical substance into another involving the movement and exchange of electrons and the breaking/creating of bonds.

• Types of Chemical Interactions:

  1. Oxidation and Reduction of Organic Compounds.

  2. Addition Reactions.

  3. Hydrolysis Reactions.

• Metabolic Pathway:

  • Sequence of reactions in living organisms, catalyzed by enzymes, that increases reaction rates without being consumed.

Organic Chemical Reaction Sequence

• Process:

  • Begins with reactants.

  • Moves through one or more transition states, forming intermediate compounds.

  • Ends with stable products with increased stability as the reaction proceeds.

Transition States

• Definition: High-energy states during a reaction where change is occurring; characterized by instability.

• Cannot be isolated and result in new products or intermediates.

Intermediates

• Form between transition states and can be isolated.

• Continue to react to yield a more stable final product.

Oxidation State / Number

• Oxidation: Removal of electrons; results in more positive behavior.

• Reduction: Addition of electrons; makes atoms more negative.

Oxidation of Ethanol

• Biological process converting ethanol to carboxylic acid.

• Ethanol is quickly absorbed into the bloodstream due to its water solubility.

• It undergoes a two-step oxidation in the liver, forming acetaldehyde (ethanal) and then acetic acid.

• The speed of this conversion affects hangover severity.

Oxidation of Methanol

• Methanol is toxic when metabolized and undergoes similar absorption as ethanol.

• The liver metabolizes methanol into formaldehyde, which cross-links proteins in cells, making it poisonous.

Reduction Reactions

• Definition: Reverse of oxidation where atoms gain electrons.

• Example Reaction: Carboxylic acid is reduced to alcohol via coenzymes that add electrons and hydrogen.

Nucleophiles

• Definition: Electron-rich species, often electronegative.

• Will donate electron pairs to electrophiles.

• Examples include ammonia, amines, and amides; all react with aldehydes during decomposition.

Electrophiles

• Definition: Electron-poor species that accept electron pairs from nucleophiles.

• Examples include aldehydes, which readily bond with nucleophilic compounds during embalming.

Factors in Embalming

• Formaldehyde: Acts as an electrophile in embalming solutions; reacts with amines, the building blocks of proteins, forming a methylene bridge.

Methylene Bridge

• A carbon unit connecting two nitrogen atoms in proteins, assisting in holding decomposing tissues together in the embalming process.

Hydrolysis

• Definition: Water-splitting addition reaction initiating decomposition processes for proteins, glycerides, nucleic acids, and lipids, facilitated by water and enzymes.