15-1 principles and applications of inorganic, organic, and biological chemistry denniston, topping,...
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15-1
Principles and Applications ofInorganic, Organic, and Biological
ChemistryDenniston, Topping, and Caret
4th ed
Chapter 15
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Power Point to Accompany
15-2
Functional Group Formulas
R1 C
O
NR2
R3amideR1, R2, R3 may beH, alkyl, aryl
R1 C
O
OH
R1 may be H,alkyl,or aromatic
Carboxylic acid
15-3
Functional Group Formulas-2
R1 C
O
O R2
R2 may not be H
ester
RC
O
OR C
O anhydrideR may be alkylor aryl
R1 C
O
Cl
R1 may be H,alkyl,or, aromatic
acid chloride
15-4
15.1 Acids: Structure and PropertiesLow molecular weight acids are water
soluble due to hydrogen bonding with water.
CH3
C OH
O
HO
HH
O HH
O H
15-5
Acids: Boiling pointsLow molecular weight acids have
abnormally high boiling points due to dimer formation via H bonding.
CH3 CO H
OCH3C
OH
O
15-6
Acids: Boiling points-2Derivative boiling points vary with
the ability to hydrogen bond.
CH3CH2C OH
O
CH3C O CH3
O
CH3 C
O
NH
H
CH3CH2CH2 OH
bp 117 o
bp 62 o
bp 118 o
bp 222 o
15-8
Acids: IUPAC NamesStart numbering at the COOH carbonReplace the -e of the alkane name with
oic acid. Name the acid:
CH3 CH CH2 CBr
OH
O
IUPAC: 3-bromobutanoic acid
(Common: -bromobutyric acid)
15-9
Examples of Carboxylic Acids
CH3 CH2 CO
OH16
Stearic acid, found in beef fat
COOHCH2
C COOHCH2COOH
OHCitric acid, found in citrus Fruits and part of the central cycle of metabolism
COOHCH OHCH3
Lactic acid, found in soremuscles and yogurt.
15-10
Reactions of Carboxylic AcidsCarboxylic acids are prepared by
oxidation of primary alcohols and aldehydes.
CH3CH2CH2OH
CH3CH2CHO CH3CH2C
OOH
H2CrO4
Warm
15-11
Reactions of Acids-2
1. Carboxylic acids are weak Lowry-Bronsted acids.
2. Acids form acid derivatives.
a) acid chlorides
b) esters (to follow)
c) amides
d) anhydrides
15-12
Reactions of Acids-31. Acids react with water to form
solutions that are weakly acidic.
CH3CO
OH + CH3CO
O +H2O H3O+
15-13
Reactions of Acids-4Acids form salts with bases.
The salts react with strong mineral acids to give the original organic acid.
CH3CO
OH + NaOH
CH3CO
OH + NaHCO3
CH3CO
ONa
CH3CO
ONa
+ H2O
+ H2O + CO2
+ NaClCH3CO
OHCH3CO
ONa + HCl CH3CO
OHCH3CO
ONa
15-14
Acids Form Esters2b. 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.
COH
OOH +CH3OH
COH
OO CH3+H2O
H3O+
15-15
15.2 EstersStructure 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.
15-16
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.
15-17
Esters: IUPAC Names-2A = ethyl propanoate
B = methyl benzoate
acid part alcohol part
C O CH3
O
CH3CH2CO
O CH2CH3
Name
A
B
15-18
Ester Reactions: PreparationCarboxylic acids react with alcohols to
give esters. The reaction is catalyzed by strong mineral acid.
+CH3 OH
H3O+
H3PO4CH2C
OOHCH3 CH3OCH2C
OCH3
+ H2O
15-19
Ester Reactions: HydrolysisThe 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).
15-20
EstersAcid hydrolysis: the products are
the acid and an alcohol.
Substitutionhere!
CH3OH
CH3CH2CO
O CH3+H2O
CH3CH2CO
OH +
H3O+
15-21
EstersBase hydrolysis (saponification): the
products are the acid salt and an alcohol.
CH3OH
CH3CH2CO
O CH3+NaOH
CH3CH2CO
ONa+
Substitutionhere!
A salt inbasicsolution.
15-22
Esters: Saponification (Soap making)Saponification (soap making) is
basic hydrolysis of fats
CH2
CH
CH2
O
O
O CO
CO
CO
R
R
R
CH2
CH
CH2
OH
OH
OH
NaO CO
R
3 NaOH
+
a soap, Na or Ksalt of a fatty acid
3R is part of a long chain (fatty) acid (C15 or C17)
15-23
Esters: Condensation PolymersPolyesters 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.
15-24
Polethylene terphthalate
COOHHOOC + OH CH2CH2OHnH+
CHOOCO
O CH2CH2OH+ H2O
Terphthalic acid 1,2-ethanediol
CCO
O CH2CH2OO
* *n
Continued condensationat each end
Repeating unit of the polymer
15-25
15.3 Acid chlorides and Acid AnhydridesAcid 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.
CH3CO
Clethanoyl chloride(acetyl chloride)
CO
ClCl4-chlorobenzoyl chloride(p-chlorobenzoyl chloride)
15-26
Acids ChloridesCarboxylic acids form acid
chlorides which are good acyl group transfer reagents.
CH2C
O
OHCH3CH2C
O
ClCH3
PCl3PCl5SOCl2
15-27
Acid chlorides-2Acid chlorides react with water
(hydrolysis) to reform the acid. Substitution of the OH for the Cl occurs at the acyl carbon.
CH3CH2CO
Cl
CH3CH2CO
OH
+
+HCl
H2OSubstitutionhere!
15-28
Acid chlorides-3Acid chlorides react with alcohols to form
esters. Substitution of the OR for the Cl occurs at the acyl carbon.
CH3CH2CO
Cl CH3OH
CH3CH2CO
O CH3
+
+ HCl
Substitutionhere!
15-29
Acid AnhydridesSymmetrical anhydrides are named by
replacing the -acid ending of the acid with –anhydride.
CH3CO
O CO
CH3
ethanoic anhydriceacetic anhydride
15-30
Acid Anhydrides-2Anhydrides are formed using the reactions
below.
CH3CO
O CO
CH3CH3CO
OH OH CO
CH3+
warmH3PO4
CH3CO
O CO
CH3CH3CO
O Cl CO
CH3+
SOCl2
OH CO
CH3
15-31
Acid Anhydrides-3Acetic anhydride reacts with
alcohols to give acetate esters.
CH3CO
O CO
CH3++
OH CH
CH3
CH3
CH3CO
O CH
CH3
CH3
OH CO
CH3
15-32
Anhydrides-4Acetic anhydride reacts with
amines to give amides.
CH3CO
O CO
CH3++
OH CO
CH3
CH3NH2
CH3NHCH3CO
15-33
15.4 Phospho and thioestersPhosphoric 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.
15-34
Phosphoric acid esters
Ester bond
adenosinetriphosphate, ATP
P
O
O
O O P
O
O
O
N
OHOH
OO CH2
N
NN
NH2
P
O
O
Anhydride bonds
15-35
ThioestersIn biochemistry, acetyl coenzyme A (CoA-SH)
reacts with acyl groups to “activate” them for further biological reaction by forming a thioester.
CH3CO
CoA-SCOO
-
CCH2COO
-
O+ CCH2
COO-
COO-
CH2COO
-
OH
+CoA-SH
Acetyl CoA