Solomons Organic Chemistry 6/E
18.1 Know the various ways in which a carboxyl group can be written in
a chemical structure.
18.2A, B Be able to apply IUPAC nomenclature rules for naming
carboxylic acids. Know the common names for methanoic and ethanoic acid.
Note for interest the derivation of some common names for carboxylic
acids. Recognize carboxylic acids as polar substances with physical
properties (e.g. bp, mp, and solubility) that would be expected for
relatively polar organic compounds. Know how to name carboxylic acid
salts.
18.2C, D Know the relative acidity of carboxylic acids on the basis
of their typical pKa range. Recognize the importance of their ready
conversion to water soluble salts by reaction with bases. Note the
utility of this reaction for discriminating between phenols and carboxylic
acids on the basis of their reaction with hydroxide and bicarbonate bases.
Consider the role of inductive effects by substituents on the acidity of a
substituted carboxylic acid.
18.2E-I Be able to recognize ester, carboxylic anhydride, acyl chloride,
amide, and nitrile functional groups and provide an IUPAC name for
specific examples of each type.
18.2J Appreciate the importance of differences and trends in carbonyl IR
absorption frequencies for their use in structure identification of acyl
compounds. Know the 1H NMR chemical shift region for hydrogens adjacent
to acyl groups and for carboxylic acid hydrogens. Know the general 13C
NMR chemical shift region for acyl carbons, and recognize it as being
distinct from that for aldehydes and ketones.
18.3 Recall the methods previously presented for synthesis of
carboxylic acids and be able to use each method for the synthesis of
specific carboxylic acid target molecules. Distinguish methods according
to which involve chain lengthening or chain elongation, and also according
to which have broad applicability versus those suited for limited
structural types of reactants.
18.4 Be able to write a detailed mechanism for a generalized
nucleophilic addition-elimination reaction at a carbonyl group bearing a
leaving group, including the structure of the tetrahedral intermediate.
Know which groups typically act as leaving groups from acyl compounds, and
the relative order of reactivity with respect to these groups in an acyl
substitution reaction. Note that the various acyl compounds are
derivatives of carboxylic acids.
18.5 Recognize acyl chlorides as the most reactive carboxylic acid
derivative. Know how to prepare an acyl chloride from the corresponding
carboxylic acid. Consider the mechanism for synthesis of an acyl chloride
using thionyl chloride. Note the variety of nucleophiles that can react
with acyl chlorides and the resulting functional group formed by each one
(including the reversion of an acyl chloride to the parent carboxylic acid
by reaction with water - a typically undesired reaction).
18.6 Know how to prepare a carboxylic acid anhydride. Note the
reactions of various nucleophiles with carboxylic anhydrides and the
functional group formed by each one (including the reversion of a
carboxylic acid anhydride to the parent carboxylic acid by reaction with
water - a typically undesired reaction).
18.7 Know how to prepare an ester by acid-catalyzed esterification and
be able to write a detailed mechanism. Note also that the mechanism is
under equilibrium control, and therefore the reverse direction represents
the mechanism and overall reaction for acid-catalyzed ester hydrolysis.
Also know how to prepare an ester from either an acyl chloride or a
carboxylic acid anhydride. Know how to cleave an ester by base-promoted
hydrolysis (saponification) and be able to write a detailed mechanism.
Recognize the structures of * (gamma) or * (delta) lactones as being
intramolecular five- and six-membered ring esters, respectively. Be able
to write detailed mechanism for either lactone formation (acid-catalyzed)
or hydrolysis (under basic conditions).
18.8 Know how to prepare an amide by reaction of an acyl chloride,
carboxylic anhydride, or by use of DCC. Recognize that amides can be
formed from esters and ammonium carboxylates but that these methods are
not as useful synthetically. Know how to hydrolyze an amide under acidic
or basic conditions and be able to write a mechanism for each process.
Know how to prepare a nitrile by dehydration of an amide. Note that
nitriles can be hydrolyzed to carboxylic acids. Be able to write a
mechanism for either acidic or basic hydrolysis of a nitrile to a
carboxylic acid. Know that lactams are cyclic amides (analogous to
lactones as cyclic esters), and recognize the central importance of the
lactam functional group in penicillin antibiotics.
18.9 Be able to prepare an *-halo carboxylic acid. Note that *-halo
carboxylic acids can be useful reactants in nucleophilic substitution
reactions.
18.10 Know the general structure of the dialkyl carbonate and carbamate
(urethane) functional groups. Be able to prepare a dialkyl carbonate or
carbamate using an appropriate alkyl chloroformate. Also be able to
prepare a carbamate by reaction of an isocyanate. Note that reaction of
amino groups with benzylchloroformate to attach a benzyloxycarbonyl group
is an important method for protecting amino groups, especially in the
chemical synthesis of peptides from amino acids (as we shall see later in
Section 24.7). Note the tendency for loss of CO2 from those functional
groups that share structural characteristics with carbonic acid (vs.
dialkyl carbonates and urethanes, which are stable functional groups).
18.11 Know that *-keto acids decarboxylate readily upon heating. Be
able to write a mechanism for this transformation starting from either the
acid itself or its carboxylate ion form. Note that decarboxylation of
*-keto acids will be an important aspect of some reactions discussed in
Chapter 19.
18.12 Consider how the properties and reactivity of carboxylic acids and
functional groups derived from them can be used in chemical tests for acyl
compounds. Note that IR spectra are an exceedingly useful qualitative
indicator of acyl functional groups, and that IR, NMR and mass
spectrometry can be used together to elucidate the complete structure of a
given compound.
18.13 Use this section as an overall summary of the reactions of
carboxylic acids and their derivatives. Look for common themes among the
reactions and organize them for yourself according to these common
attributes. Also organize them for yourself according to methods of
preparation for each type of functional group.
Assigned Problems: 1, 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17,
19a,b,c,f,h,m,u, 20a,b,g,h,i, 21, 24a,c,d,e,f,g,h,i, 25a-e, 29a,b,e, 30,
32a, 33, 34, 35, 37, 45, 52, 53
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Craig B. Fryhle, Ph.D. Office 206-535-8314 FAX 206-536-5055
Associate Professor Email fryhle@u.washington.edu
Department of Chemistry URL http://rainier.chem.plu.edu/fryhle.html
Pacific Lutheran University
Tacoma, Washington 98447 ^ ^ ^ ^ ^ ^
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