Medical Chemistry Seminar 2024 PDF

Week 11 Medical Chemistry Seminar 2024 Carboxylic Acids Department of Medical Chemistry UD Faculty of Medicine  Which of the following organic componds is the most oxidized? A. Ketone B. Ether C. Carboxylic...

Week 11 Medical Chemistry Seminar 2024 Carboxylic Acids Department of Medical Chemistry UD Faculty of Medicine  Which of the following organic componds is the most oxidized? A. Ketone B. Ether C. Carboxylic acid D. Aldehyde E. Alcohol O H O R-C-R R-O-R R C R C H C OH O H H H O Bonds 2 1 3 2 1 with O  Write at least two examples (with different types of chain/ring) for the following classes of carboxylic acids? A. Monocarboxylic B. Dícarboxylic C. Fatty acids D. Substituded A. Monocarboxylic COOH CH3COOH CH2═CH-COOH acetic acid acrylic acid benzoic acid  Write at least two examples (with different types of chain/ring) for the following classes of carboxylic acids? A. Monocarboxylic B. Dícarboxylic C. Fatty acids D. Substituded O C OH B. Dicarboxylic CH COOH CH HOOC COOH COOH O C oxalic acid phtalic acid HO fumaric acid  Write at least two examples (with different types of chain/ring) for the following classes of carboxylic acids? A. Monocarboxylic B. Dicarboxylic C. Fatty acids D. Substituded B. Fatty acids H H H H H H H H H H H H H H H H O H3C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H H H OH Stearic acid H H H H H H H H H H H H H H H H O H3C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H OH Oleic acid  Write at least two examples (with different types of chain/ring) for the following classes of carboxylic acids? A. Monocarboxylic B. Dícarboxylic C. Fatty acids D. Substituded A. Substituted Cl3C COOH trichloracetic acid (TCA) CH3 CH COOH CH3 C COOH COOH OH O OH pyruvic acid lactic acid salicylic acid  Describe the structure of carboxylic group (hybridization of the carbon, bond polarization,) and the resonance structures for carboxylate anion. Carboxylic group: d- d+ O R C d- d+ O H sp2-hybrid Carboxylate (acetate) anion : O O- CHR3- C CH3 C O- O Resonance in carboxylate anion 1.27 A° O CHH3 C ° O 1.27 A  Drew structures for the formation of H-bonds A. Between carboxylic acids B. Between carboxylic acids and water A. Between carboylic acids O H O Formation of carboxylic acid dimers R C C R (specific for these compounds) O H O B. Between carboxylic acids and water H H O O H H O H O R C C R O H O H H O O H H Which of these two compounds has higher water solubility? CH3(CH2)4COOH ˂ CH3CH2COOH 1.08 8 g/L More hydrophobic less soluble in polar solvent Which of these two compounds has higher boiling point? CH3 CH3-CH2-CH2-CH2-CH2-CH2-CH3 ˃ CH3-CH-CH2-CH2-CH3 CH3 In general: Stronger interaction with straight chains, higherBp Which of these two compounds has higher melting point? H H H H H H H H H H H H H H H H O H3C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H H H OH Stearic acid H H H H H H H H H H H H H H H H O H3C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H OH Oleic acid Stearic acid, saturated, Mp: 70 oC Oleic acid, unsaturated, cis configuration, Mp: 13 oC 1. CARBOXYLIC ACIDS NOMENCLATURE -oic acid IUPAC ending -dioic acid (for dicarbaxolic acids) -carboxylic acid IUPAC ending for ring compounds  NOMENCLATURE Number of Formula Common Name IUPAC Name carbons 1 HCO2H formic acid methanoic acid 2 CH3CO2H acetic acid ethanoic acid 3 CH3CH2CO2H propionic acid propanoic acid 4 CH3(CH2)2CO2H butyric acid butanoic acid 5 CH3(CH2)3CO2H valeric acid pentanoic acid 6 CH3(CH2)4CO2H caproic acid hexanoic acid 7 CH3(CH2)5CO2H enanthic acid heptanoic acid 8 CH3(CH2)6CO2H caprylic acid octanoic acid 9 CH3(CH2)7CO2H pelargonic acid nonanoic acid 10 CH3(CH2)8CO2H capric acid decanoic acid NOMENCLATURE Number of carbons 12 14 16 18 16 18 18 18 NOMENCLATURE: cyclic and aromatic compounds m o 3 2 O 1 p 4 C OH 5 6 Benzoic acid m o Benzenecarboxylic acid H C OH Cyclohexanecarboxylic acid O NOMENCLATURE: IUPAC and common names Designating the substituent by Greek letters (common): d g b a...CH2-CH2-CH2-CH2-CH2-COOH CH3-CH-COOH NH2 a-aminopropanoic acid alanine Designating the substituent by number (IUPAC): COOH HC-OH CH3-CH-COOH HC-OH OH lactic acid COOH 2-hydroxypropanoic acid tartaric acid 2,3-dihydroxybutanedioic acid  Naming O 2-Chloropentanoic acid CH3 CH2 CH2 CH C OH a-Chlorovaleric acid Cl O 3-Methylbutanoic acid CH3 CH CH2 C OH b-Methylbutyric acid CH3 Isovaleric acid O 2-Methylpropanoic acid CH3 CH C OH a-Methylpropionic acid Isobutyric acid CH3 O 4-Aminobutanoic Acid H2N CH2 CH2 CH2 C g-Aminobutyric Acid OH “GABA” Naming: dicarboxylic and tricarboylic acids Dicarboxylic: O O C C OH OH O O C C OH Common: Oxalic acid Oxalyl group IUPAC: Ethandioic acid Tricarboxylic: O CH2-COOH O HOOC-C-CH-COOH HOOC-C-CH2-COOH Common: Oxalosuccinic acid Oxaloacetic acid IUPAC: 2-keto-3-carboxypentanedioic acid 2-ketobutanedioic acid  Draw structures of the following carboxylic acids and determine their physiological importance A. 2 – amino – 3 – hydroxypropanoic acid C. cis – 9 – octadecenoic acid HO CH2 CH COOH CH3 CH2 C C CH2 COOH 7 7 NH2 H H Serine amino acid Oleic acid (a fatty acid) B. 3-hyroxy–3–carboxypentanedioic acid D. 2-keto-butanedioic acid Oxaloacetic acid Citric acid TCA/Citrate cycle 2. ACIDITY OF CARBOXYLIC ACIDS STRUCTURE SYSTEMATIC COMMON NAME NAME pKa HCOOH Methanoic Formic acid 3.75 acid CH3COOH Ethanoic Acetic acid 4.75 acid CH3CH2COOH Propanoic Propionic acid 4.87 acid CH3(CH2)2COOH Butanoic Butyric acid 4.81 acid CH3(CH2)3COOH Pentanoic Valeric acid 4.82 acid CH3(CH2)4COOH Hexanoic Caproic acid 4.84 acid CH3(CH2)6COOH Octanoic Caprylic acid 4.89 acid CH3(CH2)8COOH Decanoic Capric acid 4.84 acid  Acidity of carboxylic acids O O H + H CH3 O CH3 O O O O H H + + H H O O CHCH 3 3 O O Ka = = 10-4.76 O O H CH3 O CH3 O  The acidity of the carboxylic acid depends on the substitution of the R group: d- d- O d+ R C d- d+ d+ O d+ O d- O H R C d- d+ R C d- d+ O H O H Sed Sea Electron-donating groups (e.g. Electron-attracting groups (e.g. alkyl groups) decreases the electronegative atoms such as positive charge on the carbon, halogens, oxygen etc.) increases therefore acidity decreases. the positive charge on the carbon, therefore acidity increases. -CH3, -R -X -CHO -SO3H -COOH -NO2 Which halo-acid is the strongest Bronstead acid? Explain your choice. Ka CH3COOH 1.75 x 10-5 ClCH2COOH 136 x 10-5 Cl2CHCOOH 5,530 x 10-5 Cl3CCOOH 23,200 x 10-5 -Cl is electron withdrawing and delocalizes the negative charge on the carboxylate ion, lowering the PE, decreasing the ΔH, shifting the ionization to the right and increasing acid strength. Draw the structure for each of the following acids (A to D) and choose the right order of increasing acidity from a to e. A. Formic acid (methanoic acid) a. B < C < D < A B. Butanoic acid (butyric acid) b. C < D < A < B C. 2 – Keto butanedioic acid c. B < A < D < C D. 2 – hydroxybutanedioic acid d. A < B < C < D A. O D. COOH H C OH pK=3.75 pK1=2.83 HC OH Electron-donating Electron- group CH2 attracting groups B. CH3 CH2 CH2 COOH pK1=4.81 COOH COOH C. C Electron- O attracting groups CH2 B