Reactions of rganic Functional Groups Part 1: Intro & Acid-Base Review Each functional group has unique chemical reactivity. Biological molecules can become very large remember to focus on the functional groups. Most reactions only affect one functional group of a reactant at a time. Recognize the functional groups and look for changes to understand chemical reactivity. Circle the functional group that changes in the reaction below. H H H Almost ALL biochemical reactions are catalyzed by enzymes. What are catalysts? Why do our bodies need enzymes? Draw the Reaction Energy Diagram for a 1-step, exothermic rxn with a large activation energy. verlay another curve showing the rxn with a catalyst.
Acid-Base reactions are the most fundamental & frequent biochemical rxn. Complete the acid-base reactions below. 1) H + ah 2) H H H + HCl H Solubility and Acid-Base Chemistry Classify each functional group and predict water solubility for the reactants and products below. H ah + - a + H 2 H H HCl H H + H Cl - 2
Acid Base Reactions have very low activation energies. ther Biochemical Reactions have larger activation energies. Metabolism: We will study 4 of the biochemical reactions that require catalysts: 1) oxidation-reduction 2) hydration-dehydration 3) acyl group transfer 4) phosphoryl group transfer 3
Reactions of rganic Functional Groups Part 2: Redox Introduction (xidation & Reduction) xidation & Reduction Reactions of Inorganic Molecules Guidelines for Assigning xidation umbers xidation numbers are a way to keep track of electron flow in reactions. The oxidation number is the charge an atom in a compound would have if the electron pairs in each covalent bond belonged to the more electronegative atom. xidation umber Examples Exceptions Pure elements 0 The oxidation numbers for each atom in Fe(s) or 2 is zero. none Fixed charge The oxidation number is equal to Alkali metals +1 Alkaline earth metals +2 none metals its charge. Aluminum +3 F in compounds -1 F in CaF 2 is -1. F in CF 4 is -1. none Cl, Br, & I in compounds -1 if bonded to a less electronegative atom in compounds -2 H in compounds Cl is +1 when bonded with F. Cl is -1 when bonded with Br. in Mg is -2. in H 2 is -2. +1 H in H 2 is +1. none is -1 in peroxides. H is -1 when combined with metals.
Practice recognizing Redox Rxns Balance the following reaction & assign oxidation numbers to each atom. Fe 2 3 + C Fe + C 2 a) Which element is oxidized? b) Which element is reduced? Assign oxidation numbers to each atom in the following reaction. Cu (s) + H 2(g) Cu (s) + H 2 (g) Writing the xidation ½ rxn Writing the Reduction ½ rxn 2
xidation & Reduction of rganic Molecules xidation: Gain bonds to xygen Lose bonds to Hydrogen Reduction: Lose bonds to xygen Gain bonds to Hydrogen Example Breathylzer Test (rganic and Inorganic Redox Combined) H + H 2 Cr 2 7 H + Cr 2 3 Treatment of CH 3 CH 2 CH 2 CH 2 CH with a reducing agent will produce A) an aldehyde. B) a carboxylic acid. C) an alcohol. D) an alkene. E) a ketone. 3
Classify the following reactions as oxidation or reduction. H H For the reactions below, a) Predict the products for the reactions below. Remember: benzene rings are very stable so they will not react. b) Classify each function group. For alcohols, remember to indicate 1, 2, or 3. [H] H [] H [] 4
xidizing Agents: reactant that gets reduced Reducing Agents: reactant that gets oxidized For the following reaction Zn (s) + 2 HCl (aq) Zn 2+ (aq) + H 2(g) + 2 Cl - (aq) a) Write the oxidation half reaction. b) Write the reduction half reaction. c) Which reactant is the oxidizing agent? d) Which reactant is the reducing agent? 5
Reactions of rganic Functional Groups Part 3: Redox of RH & Carbonyls xidation of Alcohols Ethanol Metabolism The oxidation of a 1 alcohol 1
Reduction of Carbonyl Groups Use your knowledge of oxidation reactions to complete the reduction pathways in the following diagram. Classify the functional groups (aldehydes, ketones or alcohols) for the alcohols indicate whether they are 1, 2, 3. In biochemical reactions, reduction of carbonyl groups is carried out by AD + or ADH? 2
Antioxidants ot ALL xidation is Beneficial. xidation reactions form Free Radicals. Antioxidants are substances that trap the odd valence electron to prevent it from causing damage to our biomolecules. xidation from Free Radicals is linked with biological aging. Many antioxidants trap the unpaired electron in an aromatic benzene ring. Vitamin E is an antioxidant. Vitamin E 3
Reactions of rganic Functional Groups Part 4: Hydration-Dehydration Hydration-Dehydration Reactions Hydration of Alkenes Produces Alcohols Dehydration of Alcohols Produces Alkenes Practice reactions. a) + H 2 - H 2 b) + H 2 - H 2 c) step 2 in the break down of fatty acids H 2 SCoA
Reactions of rganic Functional Groups Part 5: Acyl Transfer What is an Acyl Group? Acyl Group Transfer Reactions 2 Pathways Catabolic & Anabolic Acyl Group Hydrolysis Reactions
What happens to carboxylic acids at physiological ph? Draw the structure of acetic acid at physiological ph. The ester for apple flavoring is methyl butanoate. Draw the skeletal-line structure for apple flavoring. Write the hydrolysis reaction for apple flavoring at physiological ph. What happens to amines at physiological ph? Draw ethanamine at physiological ph. Predict the products of the following enzyme catalyzed hydrolysis reactions at physiological ph. H 2 H enzyme 2
Acyl Derivative Formation Add the missing reactants. Show the reaction to form rum flavoring (ethyl formate) using acyl derivative formation. 3
Predict the hydrolysis products of aspartame at physiological ph. 4
Reactions of rganic Functional Groups Part 6: Phosphoryl Grp Transfer What is the effect of physiological ph on phosphate esters? R P H ph 7.4 H Phosphoryl Group Transfer Reactions Phosphate esters are formed when 1 or more of the H atoms of phosphoric acid is (are) replaced with 1 or more R groups. Phosphoanhydride bonds form when the atoms of one phosphate group bonds with the P atom of another phosphate group. Label the Phosphate groups (Pi), Phosphate ester bonds and Phosphoanhydride bonds in the compound below.
Phosphoryl groups play an important role in glycolysis. Glycolysis is the biochemical pathway that breaks down glucose to produce energy. 1 st step of Glycolysis Phosphoryl groups also play a central role in the way energy is transferred in biochemical reactions. ur body stores and transports energy in the phosphoanhydride bonds of ATP. Draw an arrow to the phosphoanhydride bond that is broken and reformed as ATP converts back and forth to ADP. 2
Reactions of rganic Functional Groups Part 7: Coenzymes & Redox Rxns xidation and Reduction reactions ALWAYS occur together. To oxidize or reduce a biological molecule, we need a second compound that can donate or accept the electrons. Coenzymes are the second compound. Coenzymes: special molecules that shuttle electrons Common xidizing and Reducing Agents xidizing Agents Formula or Rxn Bleach acl xygen 2 Hydrogen peroxide H 2 2 Chromium(VI) Cr 6+ Manganese (VIII) Mn - 4 AD + Coenzyme AD + + 2H + + 2e - ADH + H + FAD Coenzyme FAD + 2[H] FADH 2 Reducing Agents Hydrogen H 2 ADPH Coenzyme ADPH + H + ADP + + 2[H] ote the difference
Coenzymes a closer look at the 3 Most Important FAD/FADH 2 FAD is the H Acceptor when C=C (double) bonds form Circle the reactive region of FAD and FADH 2. Diagram the reaction below to indicate the oxidation and reduction ½ reactions. Label each ½ reaction (oxidation or reduction). For the coenzyme, label FAD/FADH 2. H H + + H H 2
AD + /ADH AD + is the H Acceptor in Most xidations Diagram the reaction below to indicate the oxidation and reduction ½ reactions. Label each ½ reaction (oxidation or reduction). For the coenzyme, label AD + /ADH. H + + H ADPH/ADP + ADPH is the H Donor in Reduction Reactions Diagram the reaction below to indicate the oxidation and reduction ½ reactions. Label each ½ reaction (oxidation or reduction). For the coenzyme, label ADPH/ADP +. 3
The reactions for two important pairs of coenzymes are shown below. a) ame them: AD +, ADH, FAD, and FADH 2. Hint: Look closely at the chemical structures to find the differences. b) Label each one of the coenzymes as an oxidizing agent or reducing agent. Reaction 1 a) - P H H H 2 + H 2 H - P H H H H H 2 H 2 P - P - H H H H b) Reaction 2 a) H H H H H H H H H H H P H P H H H 2 H P H P H H H 2 b) 4