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2 OF O RGANIC C OMPOUNDS C HOLESTEROL 2.1 STRUCTURE AND PHYSICAL - PowerPoint PPT Presentation

May 25, 2023 •381 likes •703 views

P ROPERTIES 2 OF O RGANIC C OMPOUNDS C HOLESTEROL 2.1 STRUCTURE AND PHYSICAL PROPERTIES Dipole-Dipole Forces Blue arrow: direction of net dipole moment Cl Cl C C Cl Cl H Cl Cl H Tetrachloromethane Dichloromethane Te bond moments

  1. P ROPERTIES 2 OF O RGANIC C OMPOUNDS C HOLESTEROL

  2. 2.1 STRUCTURE AND PHYSICAL PROPERTIES Dipole-Dipole Forces Blue arrow: direction of net dipole moment Cl Cl C C Cl Cl H Cl Cl H Tetrachloromethane Dichloromethane Te bond moments cancel Te bond moments do not and there is no net polarity cancel and there is a net polarity Section 2.1 Structure and Physical Properties Dipole-Dipole Forces

  3. Figure 2.1 Physical Properties of Isobutane and Acetone Te physical properties of these two molecules refmect their dipole moments. Isobutane, which has a dipole moment near zero, has a low boiling point of -11.7 o C. Acetone, however, has a large dipole moment of 2.91 D and a boiling point of 56–57 o C. H O CH 3 C C CH 3 CH 3 CH 3 CH 3 Isobutane, bp –11.7 o C Acetone, bp 56-57 o C Section 2.1 Structure and Physical Properties Figure 2.1

  4. London Forces CH 3 CH 2 Br CH 3 CH 2 Cl Boiling point 38.4°C 12.3°C Molecular weight 109 amu 64.5 amu CH 3 H 2 CH 2 CH 2 CH 3 CH 3 CH 2 CH 2 CHvCH 2 CH 3 pentane hexane (bp 36 °C) (bp 69 °C) Section 2.1 Structure and Physical Properties London Forces

  5. Figure 2.2 London Forces (a) T e approach of one nonpolar molecule induces a transient dipole in its neighbor “end-to-end”. (b) Several nonpolar molecules interacting side-by-side by London interactions. induced dipoles induced dipoles δ + δ - δ - δ - δ + δ + δ + δ + δ - δ + δ - δ - δ - δ + δ - δ + δ + δ - (b) (a) CH 3 CH 3 C CH 3 CH 3 CH 2 CH 2 CH 2 CH 3 CH 3 pentane, bp 36 o C 2,2-dimethylpropane, bp 10 o C Section 2.1 Structure and Physical Properties Figure 2.2 London Forces

  6. Figure 2.3 London Forces Molecular models show how the difg erence in surface contact depends on molecular shapes. 2,2-dimethylpropane (neopentane) n -pentane small area of surface contact large area of surface contact Section 2.1 Structure and Physical Properties Figure 2.3 London Forces

  7. Hydrogen-Bonding Forces H H H H O H N H N H H H H O Hydrogen bond Hydrogen bond H H O C H H H H O C Hydrogen bond H H CH 3 CH 2 OH CH 3 CH 3 O ethanol, bp 78.5 o C dimethyl ether, bp -24 o C Section 2.1 Structure and Physical Properties Hydrogen Bonding Forces

  8. Figure 2.4 Hydrogen Bonding in Ethanol Section 2.1 Structure and Physical Properties Figure 2.4 Hydrogen Bonding in Ethanol

  9. Solubility Hydrogen bond H CH 2 O CH 3 H H O Hydrogen bond H O H Section 2.1 Structure and Physical Properties Solubility

  10. Figure 2.5 Water-and Fat-Soluble Vitamins OH HO OH NH 2 OH O O OH CH 3 N O OH HO N OH OH CH 3 N N Vitamin C Riboflavin O Vitamin B 6 Water-soluble vitamins OH Vitamin A (retinol) O H CH 3 (CH 2 ) 3 C (CH 2 ) 3 (CH 2 ) 7 C CH 3 HO CH 3 CH 3 Vitamin E HO Vitamin D 3 Fat-soluble vitamins Section 2.1 Structure and Physical Properties Figure 2.5 Water Soluble and Fat Soluble Vitamins

  11. 2.3 BRØNSTED-LOWRY ACIDS AND BASES this bond forms H + H + H O O H Cl Cl this bond H H breaks H + + H N H O H H O H H N H H H H H O O H + + H H H CH 3 C O O CH 3 C O O H H acetate, hydronium ion, acetic acid water, a base conjugate base conjugate acid H H + + CH 3 N H O H O H CH 3 N H H H H H methylamine hydronium ion methylammonium ion, water, conjugate acid conjugate base Section 2.2-2.3 Chemical Reactions: Acid-Base Reactions Brønsted-Lowry Acids

  12. 2.3 LEWIS ACIDS AND BASES Cl F Aluminum can accept Al Cl B F Boron can accept an electron pair an electron pair Cl F aluminum trichloride boron trifluoride + FeBr 3 Br FeBr 3 Br Br Br Lewis base Lewis acid F F H F B O CH 3 F B O CH 3 CH 3 F F CH 3 Section 2.2-2.3 Chemical Reactions: Acid-Base Reactions Lewis Acids

  13. 2.4 OXIDATION-REDUCTION REACTIONS H O O [O] [O] OH H C H C H C H OH H methanol methanal methanoic acid (formaldehyde) (formic acid) CH 3 CH 3 O K 2 Cr 2 O 7 CH 3 C CH 2 O H CH 3 C C OH H 2 SO 4 CH 3 CH 3 H H H H Pt + H 2 C C H C C H H OH H H H H + H 2 O C C H H H C C H ethene ethane H H H H H H ethene ethanol Pt + 2 H 2 H C C H H C C H H H ethyne Section 2.4 Redox Reactions Examples of Redox Reactions

  14. Biochemical Redox Reactions NAD + + 2H + + 2e - NADH + H + oxidized form reduced form + 2H + + 2e - FAD FADH 2 oxidized form reduced form OH O NAD + + + H + + NADH CO 2 H CH 2 C CO 2 H CO 2 H CH 2 C CO 2 H H oxaloacetic acid malic acid H H CH 3 (CH 2 ) 6 CH 2 CH 2 (CH 2 ) 6 CO 2 H enzyme CH 3 (CH 2 ) 6 CH 2 C C CH 2 (CH 2 ) 6 CO 2 H C C H H H H FAD FADH 2 stearic acid oleic acid Cyt P450 + H + NADP + + OH + H 2 O H + + NADPH O 2 R R reduced form oxidized form Section 2.4 Redox Reactions, II Examples of Biochemical Redox Reactions

  15. 2.5 CLASSIFICATION OF ORGANIC REACTIONS addition H Br H H + C C H Br H C C H H H H H bromoethane ethene elimination H OH H H + H C C CH 3 C C H OH H 2 SO 4 H CH 3 H H propene 2-propanol substitution X + Y + Y X R R substitution Br + + OH Br CH 3 CH 3 OH bromomethane methanol Section 2.5 Classifjcation of Organic Reactions Examples of Addition, Elimination, and Substitution Reactions

  16. 2.5 CLASSIFICATION OF ORGANIC REACTIONS this bond breaks this bond breaks these bonds form O O hydrolysis + HO + H CH 3 C O CH 3 CH 3 C OH H O CH 3 methyl acetate acetic acid methanol these bonds break this bond forms this bond forms O O condensation + + HO CH 3 C OH CH 3 C O CH 3 H H O CH 3 acetic acid methanol methyl acetate H rearrangement CH 3 C CH CH 2 CH 3 CH CH CH 2 Br Br Section 2.5 Classifjcation of Organic Reactions, II Examples of Hydrolysis, Condensation, and Rearrangement Reactions

  17. 2.6 CHEMICAL EQUILIBRIUM AND EQUILIBRIUM CONSTANTS forward reaction m A + n B p X + q Y reverse reaction [X] p [Y] q K equilibrium = [A] m [B] n K eq + HBr CH 2 CH 2 CH 3 CH 2 Br ethene [CH 3 CH 2 Br] = 10 8 K equilibrium = [CH 2 =CH 2 ][HBr] O O K eq + + CH 3 CH 2 OH H 2 O C C CH 3 OH CH 3 OCH 2 CH 3 ethanoic acid ethanol ethyl ethanoate [CH 3 CO 2 CH 2 CH 3 ] [H 2 O] K equilibrium = = 4.0 [CH 3 CO 2 H] [CH 3 CH 2 OH] Section 2.6 Chemical Equilibrium and Equilibrium Constants Equations for Equilibrium Constants

  18. Le Châtelier’s Principle H H O O H C + CH 3 CH 2 OH + C O H H C C OCH 2 CH 3 H 2 O Adding ethanol pushes Removing water H H the reaction to the right pulls the reaction to the right Section 2.6 Chemical Equilibrium and Equilibrium Constants Le Châtelier’s Principle

  19. 2.7 EQUILIBRIA IN ACID-BASE REACTIONS K eq Table 2.1 A - + H 3 O + K a and pK a Values of + H 2 O HA Common Acids Acid K a pK a [H 3 O + ][A - ] HBr 10 9 -9 K equilibrium = 10 7 HCl -7 [HA][H 2 O] H 2 SO 4 10 5 -5 10 1 HNO 3 -1 [H 3 O + ][A - ] HF 6 x 10 -4 3.2 K a = K eq [H 2 O] = [HA] 2 x 10 -5 CH 3 CO 2 H 4.7 (CF 3 ) 3 COH 2 x 10 -5 4.7 3 x 10 -11 CH 3 CH 2 SH 10.6 CF 3 CH 2 OH 4 x 10 -13 12.4 3 x 10 -16 CH 3 OH 15.5 (CH 3 ) 3 COH 1 x 10 -18 18 10 -25 CCl 3 H 25 10 -25 25 HC ≡ CH 10 -36 NH 3 36 CH 2 =CH 2 10 -44 44 10 -49 CH 4 49 Section 2.7 Equilibria in Acid-Base-Reactions Table 2.1 Acidity of Common Acids

  20. 2.7 EQUILIBRIA IN ACID-BASE REACTIONS, II weaker acid stronger base than H 3 O + than H 2 O conjugate acid-base pair + H 3 O + H 2 O CH 3 CO 2 CH 3 CO 2 H conjugate acid-base pair weaker base than stronger acid CH 3 CO 2- than CH 3 CO 2 H A - + H 2 O HA + OH - [HA][OH - ] K b = K eq [H 2 O] = [A - ] K b + OH – CH 3 CO 2– + H 2 O CH 3 CO 2 H strong base weak base Section 2.7 Equilibria in Acid-Base-Reactions, II Weak and Strong Acids, Conjugate Acids and Bases

  21. 2.7 EQUILIBRIA IN ACID-BASE REACTIONS, III Table 2.2 K b and pK b Values of Common Bases Acid K b pK b 4 x 10 -10 9.4 K b NH 2 CH 3 NH 3+ + OH - + H 2 O CH 3 NH 2 weak base strong base CH 3 CO 2 – 5 x 10 -10 9.3 1.6 x 10 -5 4.8 C ≡ N – 1.7 x 10 -5 NH 3 4.8 4.3 x 10 -4 CH 3 NH 2 3.4 CH 3 O – 3 x 10 -16 -1.5 weaker base stronger acid than OH - than H 2 O conjugate acid-base pair + + CH 3 NH 3 CH 3 NH 2 H 2 O OH conjugate acid-base pair weaker acid stronger base than CH 3 NH 3+ than CH 3 NH 2 Section 2.7 Equilibria in Acid-Base-Reactions, III Table 2.2 Basicity of Common Bases

  22. 2.8 EFFECT OF STRUCTURE ON ACIDITY O O H O S O H CH 3 O S OH O O sulfuric acid, methane sulfonic acid, a strong acid a strong acid H N H H N CH 2 CH 3 H H ethylamine ammonia pK b 4.74 pK b 3.25 (weak base) (weak base) K a = 10 -16 CH 3 O - H 3 O + + + H 2 O CH 3 OH O O K a = 1.8 � 10 -5 C C CH 3 CO 2- H 3 O + + CH 3 CO 2 H + H 2 O CH 3 O CH 3 O H H H O O O Cl C C H C C C C Cl O H O H H H H O H pK a = 2.9 pK a = 4.7 Section 2.8 Efgect of Structure on Acidity Efgect of Structure on Acidity, Resonance, and Inductive Efgects

  23. 2.9 INTRODUCTION TO REACTION MECHANISMS A P reactant product Step 1 A M intermediate reactant Step 2 M P intermediate product Section 2.9 Introduction to Organic Reaction Mechanisms Reactions Tat Proceed Trough an Intermediate

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