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.