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Power Point to Accompany Principles and Applications of Inorganic, Organic, and Biological Chemistry Denniston, Topping, and Caret 4th ed Chapter 15 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15-1 Functional Group Formulas O R1 C OH O R2 R1 C N Carboxylic acid amide R3 R1 may be H, R1, R2, R3 may be alkyl,or aromatic H, alkyl, aryl 15-2 Functional Group Formulas-2 O R1 C O R2 ester R2 may not be H O O R C O CR O R1 C Cl acid chloride R1 may be H, alkyl,or, aromatic anhydride R may be alkyl or aryl 15-3 15.1 Acids: Structure and Properties Low molecular weight acids are water soluble due to hydrogen bonding with water. O H H O O H C O H H CH3 H O H 15-4 Acids: Boiling points Low molecular weight acids have abnormally high boiling points due to dimer formation via H bonding. O H O CH3 C C CH3 O H O 15-5 Acids: Boiling points-2 Derivative boiling points vary with the ability to hydrogen bond. O CH3CH2CH2 OH bp 117 o O bp 118 O CH3C O CH3 bp 62 CH3CH2C OH o o H CH3 C N bp 222 o H 15-6 Acids: Common Names O formic acid HC OH acetic acid O CH3C OH O butyric acid CH3CH2 CH2 C OH 15-7 Acids: IUPAC Names Start numbering at the COOH carbon Replace the -e of the alkane name with oic acid. Name the acid: O Br CH3 CH CH2 C OH IUPAC: 3-bromobutanoic acid (Common: g-bromobutyric acid) 15-8 Examples of Carboxylic Acids O CH3 CH2 16C OH Stearic acid, found in beef fat COOH CH2 Citric acid, found in citrus HO C COOH Fruits and part of the central cycle of metabolism CH2 COOH COOH H C OH CH3 Lactic acid, found in sore muscles and yogurt. 15-9 Reactions of Carboxylic Acids Carboxylic acids are prepared by oxidation of primary alcohols and aldehydes. CH3CH2CH2OH O H2CrO4 O CH3CH2C OH Warm CH3CH2CH 15-10 Reactions of Acids-2 1. Carboxylic acids are weak LowryBronsted acids. 2. Acids form acid derivatives. a) acid chlorides b) esters (to follow) c) amides d) anhydrides 15-11 Reactions of Acids-3 1. Acids react with water to form solutions that are weakly acidic. O CH3C OH + H2O O CH3CO + H3O+ 15-12 Reactions of Acids-4 Acids form salts with bases. The salts react with strong mineral acids to give the original organic acid. O O CH3C OH + NaOH CH3C ONa + H2O O O CH3C OH + NaHCO3 CH3C ONa + H2O + CO2 O CH3C ONa + HCl O CH3C OH+ NaCl 15-13 Acids Form Esters 2b. Carboxylic acids react with alcohols to form esters, an important group in biochemistry. The reaction requires an acid catalyst. The reaction is an equilibrium reaction. O O C OH C O CH3+H O + CH OH 2 3 OH OH H3O+ 15-14 15.2 Esters Structure and Physical Properties Esters are mildly polar Many have pleasant aromas E. g. isoamyl acetate=banana oil ethyl butanoate=pineapple aroma Boil at approximately the same temperature as carbonyls with comparable molecular weight. 15-15 Esters: IUPAC Names 1. Name the alkyl group attached to the oxygen atom first. (Alcohol part of the ester) 2. Base name for the acid part of the structure from the longest chain ending in the C=O. Change the oic acid of the acid name to oate and add this to the name in 1 as a second word. 15-16 Esters: IUPAC Names-2 A = ethyl propanoate B = methyl benzoate O N CH3CH2C O CH2CH3 A a acid part alcohol part m O C O CH3 B e 15-17 Ester Reactions: Preparation Carboxylic acids react with alcohols to give esters. The reaction is catalyzed by strong mineral acid. O O + H3O CH3CH2C O CH3 CH3CH2C OH H3PO4 + CH3 OH + H2O 15-18 Ester Reactions: Hydrolysis The main reaction of esters is hydrolysis, reaction with water. However, the uncatalyzed reaction is slow and either mineral acid or base is used as a catalyst. When stoichiometric base is used, the reaction is called saponification (soap making). 15-19 Esters Acid hydrolysis: the products are the acid and an alcohol. O CH3CH2C O CH3 + H2O Substitution here! H3 + O O CH3CH2C OH +CH3OH 15-20 Esters Base hydrolysis (saponification): the products are the acid salt and an alcohol. O CH3CH2C O CH3 + NaOH Substitution here! A salt in basic solution. O CH3CH2C ONa +CH3OH 15-21 Esters: Saponification (Soap making) Saponification (soap making) is basic hydrolysis of fats CH2OH O CH2O C R CH OH O 3 NaOH CH OH 2 CH O C R + O O CH2O C R 3 NaO C R R is part of a long chain (fatty) acid (C15 or C17) a soap, Na or K salt of a fatty acid 15-22 Esters: Condensation Polymers Polyesters are condensation polymers formed by eliminating a small molecule (e. g. H2O) when combining a diacid and a diol. Polyethylene terphthalate (PETE) is used to make Mylar, shatterproof plastic bottles, and polyester fabric. 15-23 Polethylene terphthalate HOOC COOH + n HO CH2CH2OH Terphthalic acid HOOC O * C H+ 1,2-ethanediol O C O CH2CH2OH + H2O Continued condensation at each end O C O CH2CH2O n* Repeating unit of the polymer 15-24 15.3 Acid chlorides and Acid Anhydrides Acid chlorides are named: by replacing the –ic acid ending of the common name with –yl chloride. by replacing the –oic acid ending of the IUPAC name with –oyl chloride. O ethanoyl chloride CH3C Cl (acetyl chloride) Cl O 4-chlorobenzoyl chloride C Cl (p-chlorobenzoyl chloride) 15-25 Acids Chlorides Carboxylic acids form acid chlorides which are good acyl group transfer reagents. PCl3 O PCl 5 CH3CH2 C Cl CH3 CH2C OH SOCl2 O 15-26 Acid chlorides-2 Acid chlorides react with water (hydrolysis) to reform the acid. Substitution of the OH for the Cl occurs at the acyl carbon. O CH3CH2C Cl + H2O Substitution here! O CH3CH2C OH +HCl 15-27 Acid chlorides-3 Acid chlorides react with alcohols to form esters. Substitution of the OR for the Cl occurs at the acyl carbon. O CH3CH2C Cl + CH3OH Substitution here! O CH3CH2C O CH3 + HCl 15-28 Acid Anhydrides Symmetrical anhydrides are named by replacing the -acid ending of the acid with –anhydride. O O ethanoic anhydrice CH3C O C CH3 acetic anhydride 15-29 Acid Anhydrides-2 Anhydrides are formed using the reactions below. O O O O warm + CH3C OH HO C CH3 H3PO4 CH3C O C CH3 O CH3C O + O Cl C CH3 O O CH3C O C CH3 SOCl2 O HO C CH3 15-30 Acid Anhydrides-3 Acetic anhydride reacts with alcohols to give acetate esters. O O CH3C O C CH3 + CH3 HO CH CH3 CH3 O CH3C O CH + CH3 O HO C CH3 15-31 Anhydrides-4 Acetic anhydride reacts with amines to give amides. O O CH3C O C CH3 + CH3NH2 O CH3C NH CH3 + O HO C CH3 15-32 15.4 Phospho and thioesters Phosphoric acid reacts with alcohols to give esters. The ester can then react with a second or third acid to give phosphoric acid anhydrides. ADP and ATP of biochemistry fame are the important examples of phosphoric acid esters. 15-33 Phosphoric acid esters NH2 Ester bond Anhydride bonds O O N N O O P O P O P O CH2 O O O adenosine triphosphate, ATP N N OH O 15-34 OH Thioesters In biochemistry, acetyl coenzyme A (CoA-SH) reacts with acyl groups to “activate” them for further biological reaction by forming a thioester. - O COO CoA-S C CH3 + C O Acetyl CoA CH2 COO COO CH2 HO C COO CH2 COO + CoA-SH 15-35 The End Acids and Derivatives 15-36