110b Exam 2 Review Sheet- Spring Semester 2010
Review Session: Wednesday, February 24, 7:00 PM, SN Aud
Examination: Friday, February 26, 8:00 AM, SN Aud
9 Goals for Chapter 16:
1.
Nomenclature- be familiar with examples in the text.
2.
Synthesis of aldehydes: PCC oxidation of 1° alcohols, know the reagent
composition and reaction (review the mechanism). DIBAL reduction of
esters; know the structure of the reagent and mechanism of reaction.
Extend your mechanistic insights to the DIBAL reduction of nitriles.
Li(Ot-Bu)3AlH reduction of acid chlorides to aldehydes: mechanism and
utility in synthesis.
3.
Synthesis of ketones: Review those from last semester and chapter 15.
Ketones from the reaction of nitriles with RMgX or RLi, know the
mechanism of this reaction and identify the unstable imine intermediate.
4.
Acetals and ketals and their hemi- forms. Be able to identify these
functional groups. Know the mechanism of formation/hydrolysis for an
acetal (e.g., acetaldehyde + 2CH3OH + H+(cat.)). Be aware of the utility
of acetals and ketals [and their thio (sulfur) analogs] as protecting groups
in organic synthesis.
5.
The addition of amines to aldehydes and ketones: mechanisms for imine
and enamine formation. Applications of this chemistry. You should be
familiar with the related chemistry of oximes and hydrazones.
6.
The addition of HCN to aldehydes and ketones. Mechanism of
cyanohydrin formation and synthetic utility of products.
7.
The Wittig reaction. Mechanism of reaction, definition of ylide, betaine,
oxaphosphatane. The Horner-Wadsworth-Emmons Modification. Utility
in synthesis.
8.
Spectroscopic evidence for aldehydes and ketones. 1H, 13C NMR and
IR.
9.
Be able to employ the reactions of chapter 16 in synthetic proposals,
predict the products, and mechanistic analyses.
9 Goals for Chapter 17:
1.
Acidity of the -hydrogen of carbonyl compounds; know the pKa’s of
acetone, nitromethane, and acetonitrile. Why are these hydrogens
acidic? What does an enolate ion look like?
2.
Keto-enol tautomerism; rationalize the preferred keto form on the basis of
select bond strengths.
3.
Why do certain optically active aldehydes and ketones racemize easily?
4.
Know the mechanisms of base-promoted  -halogenation of aldehydes
and ketones and the haloform reaction. What is the synthetic utility of
these reactions?
5.
The aldol reaction. Know the mechanism of the general reaction, focusing
on three issues: (i) the “forward” direction, completely reversible, to
yield a -hydroxy ketone or aldehyde, (ii) the “reverse” direction, or
retro-aldol (usually from  -hydroxy ketones), and (iii) irreversible
dehydration of aldol addition products to yield conjugated systems (this
happens at higher temperatures as well as for products whose elimination
of H2O results in conjugated systems). Intramolecular aldol reaction gives
a ring as a product. Acid-catalyzed variant of the aldol reaction:
mechanism of reaction.
6.
Extend your mechanistic insights to examples of crossed aldols, RCHO
+ X, where X = aldehydes, ketones (the Claisen-Schmidt reaction),
nitroalkanes (products elaborated to amines via H2/Ni), and nitriles. R
of course, is an aldehyde lacking an acidic  -hydrogen. (We saw three
examples).
7.
Lithium enolates. Thermodynamic and kinetic enolates. Directed aldol
reactions: mechanism of reaction. Alkylation of lithium enolates.
8.
Definition of 1,2 vs. 1,4 addition to , unsaturated systems; mechanism
of 1,4 attack; conjugate addition; Michael addition; mechanism of the
Robinson annulation.
9.
Be able to employ the reactions of chapter 17 in synthetic proposals, in
“predict the product” type of questions, and mechanistic analyses.