Chapter 13 - Acids, Amines, Esters, and Amides Flashcards

pH Scale and Common Substances

• The transcript provides a scale of common substances arranged by their pH levels, ranging from highly acidic to highly basic:     - pH 14: Bleach     - pH 12: Soapy water     - pH 11: Ammonia solution     - pH 10: Milk of Magnesia     - pH 9: Baking soda     - pH 8: Sea water     - pH 7: Distilled water (Neutral)     - pH 6: Urine     - pH 5: Black coffee     - pH 4: Tomato juice     - pH 3: Orange juice     - pH 2: Lemon juice     - pH 1: Gastric acid

Characteristics of Organic Acids and Bases

• Strong Acids vs. Organic Acids:     - Strong inorganic acids, such as Hydrochloric acid ($HCl$), dissociate completely in water: $HCl + H_2O \rightarrow H_3O^+ + Cl^-$.     - Organic acids, specifically carboxylic acids like Acetic acid ($CH_3COOH$) or Propanoic acid ($CH_3CH_2COOH$), are weak acids and exist in equilibrium with their dissociated forms: $CH_3CH_2COOH + H_2O \rightleftharpoons CH_3CH_2COO^- + H_3O^+$.
• Organic Bases (Amines):     - Organic bases like Methylamine ($CH_3NH_2$) or Ethylamine ($CH_3CH_2NH_2$) react with water to produce hydroxide ions: $CH_3CH_2NH_2 + H_2O \rightleftharpoons CH_3CH_2NH_3^+ + OH^-$.
• Neutralization basics:     - Acids and bases can be compared and contrasted. While strong bases like Sodium Hydroxide ($NaOH$) dissociate fully, organic amines act as weak bases.

Fundamental Chemical Definitions and Processes

• Neutralization Reaction:     - Definition: The reaction of an acid with a base to produce water ($H_2O$) and a salt (an ionic compound).     - pH Change: The pH of the resulting products is closer to 7 than the pH of the initial reactants.
• Protonation and Deprotonation:     - Protonated: The process of gaining an $H^+$ ion, or a chemical species that has successfully gained an $H^+$ ion.     - Deprotonated: The process of losing an $H^+$ ion, or a chemical species that has lost an $H^+$ ion.
• Saponification Reaction:     - Definition: The conversion of a fat, oil, or lipid into soap (which is the salt of a fatty acid) through the addition of a strong base.
• Ion-Dipole Attraction:     - Definition: The attraction between an ion (like a cation or anion) and the dipole of a polar molecule, such as the dipole found in water molecules.
• Water Solubility:     - Definition: The ability of a substance to dissolve in or mix with water easily. This is often enhanced when a molecule is in its ionic (charged) form, such as in the salt form of a drug.

Reaction Prediction and Strategies

• To predict the outcome of a reaction, three specific steps should be followed:     1. Highlight the reactive functional group.     2. Look at reaction conditions, including other reactants (e.g., presence of $H^+$, $NaOH$, or $HCl$).     3. Determine the type of reaction (Neutralization, Condensation, or Hydrolysis), plan the mechanism, and then predict the products.

Neutralization Examples and Pharmaceutical Applications

• Example of Carboxylic Acid Neutralization:     - $CH_3(CH_2)_9COOH + NaOH \rightarrow CH_3(CH_2)_9COO^-Na^+ + H_2O$
• Pharmaceutical examples of salts used to increase solubility:     - Oxycodone is often administered in a form that reacts with $HCl$.     - Fexofenadine $HCl$ is another example where the hydrochloride salt is used.

Esters and Amides: Structural and Biological Context

• Similarities between Esters and Amides:     - Both contain a carbonyl group ($C=O$) bonded to a heteroatom (Oxygen for esters, Nitrogen for amides).
• Esters:     - General Structure: $R-CO-O-R'$     - Biological Significance: Esters are found in triglycerides, which are a primary component of lipids (Chapter 15).
• Amides:     - General Structure: $R-CO-NR'R''$     - Biological Significance: Amides constitute the peptide bond in proteins. An example provided is the dipeptide Thr-Val (threonylvaline).

Condensation and Hydrolysis Reactions

• Condensation Reaction (Dehydration Synthesis):     - Definition: The reaction of two molecules that produces one larger molecule and a small molecule byproduct, usually water ($H_2O$).     - Formation of an Ester: Carboxylic Acid + Alcohol $\xrightarrow{H^+}$ Ester + Water.         - Example: Acetic acid + Ethanol $\xrightarrow{H^+}$ Ethyl acetate + Water ($CH_3COOH + HOCH_2CH_3 \rightarrow CH_3COOCH_2CH_3 + H_2O$).     - Formation of an Amide: Carboxylic Acid + Amine $\xrightarrow{H^+}$ Amide + Water.         - Example: Propanoic acid + Methylamine $\rightarrow$ N-methylpropanamide + Water ($CH_3CH_2COOH + NH_2CH_3 \rightarrow CH_3CH_2CONHCH_3 + H_2O$).
• Hydrolysis Reaction:     - Definition: The reaction of water with a large molecule that causes the molecule to divide into two pieces.     - Biological context: This is an important reaction for the digestion (breaking down) of carbohydrates, triglycerides, and proteins.     - Example of Ester Hydrolysis: $CH_3COOCH_2CH_3 + H_2O \xrightarrow{H^+} CH_3COOH + CH_3CH_2OH$.