1. Chapter 24 Amines
24.8 Synthesize m-ethylphenol from benzene
(Hint: Use a diazo intermediate = Sandmeyer Rxn)

2. Diazonium Salts: The Sandmeyer Reaction
Primary arylamines react with HNO2, yielding stable arenediazonium salts
The N2 group can be replaced by a nucleophile
Sequence of (1) nitration, (2) reduction, (3) diazotization, and (4) nucleophilic substitution leads to many different products

3. Spectroscopy
IR -NH2
-NHR
-NR2

4. Spectroscopy
NMR
C9H13N

5. Chapter 26: Biomolecules: Amino Acids Peptides and Proteins
Chiral C

6. Chirality of Amino Acids
Glycine, 2-amino-acetic acid, is achiral
In all the others, the  carbons of the amino acids are centers of chirality
The stereochemical reference for amino acids is the Fischer projection of L-serine
Proteins are derived exclusively from L-amino acids
D-glyceraldehyde
L-glyceraldehyde

7. The D-Sugar Family
Correlation is always with D-(+)-glyceraldehyde (R)

8. Draw Fisher diagrams of L-Alanine (R = CH3) and L-cysteine (R = CH2-SH)
and assign stereochemistry as R or S

9. Amino Acids: pKa and
Isoelectric points

11. Histidine
Contains an imidazole ring that is partially protonated in neutral solution
Only the pyridine-like, doubly bonded nitrogen in histidine is basic.
The pyrrole-like singly bonded nitrogen is nonbasic because its lone pair of electrons is part of the 6  electron aromatic imidazole ring (see Section 24.4).

12. 26.2 Isoelectric Points
In acidic solution, the carboxylate and amine are in their conjugate acid forms, an overall cation
In basic solution, the groups are in their base forms, an overall anion
In neutral solution cation and anion forms are present
This pH where the overall charge is 0 is the isoelectric point, pI

13. Titration Curves of Amino Acids
pKa’s determined from titration curve
If pKa values for an amino acid are known the fractions of each protonation state can be calculated (Henderson-Hasselbach Equation)
pH = pKa – log [A-]/[HA]

14. pI of any amino acid is the average of the two pKa’s that involve the neutral zwitterion

15. 26.3 Synthesis of Amino Acids: Reductive Amination of -Keto Acids
Reaction of an -keto acid with NH3 and a reducing agent (see Section 24.6) produces an -amino acid

16. 26.3 Synthesis of Amino Acids: Chemical Resolution of R,S Amino Acids
Convert amino group into amide and react with a chiral amine to form diastereomeric salts
Separate salts, convert back to the aa by hydrolysis of the amide
Enzymic Resolution
Enzyme selectively catalyzes hydrolysis of one enantiomer

17. 26.10 Peptide Synthesis
Peptide synthesis requires that different amide bonds must be formed in a desired sequence
The growing chain is protected at the carboxyl terminal and added amino acids are N-protected
After peptide bond formation, N-protection is removed

18. Carboxyl Protecting Groups
Usually converted into methyl or benzyl esters
Removed by mild hydrolysis with aqueous NaOH
Benzyl esters are cleaved by catalytic hydrogenolysis of the weak benzylic C–O bond

19. Amino Group Protection
An amide that is less stable than the protein amide is formed and then cleaved after amide bond formed
The tert-butoxycarbonyl amide (BOC) protecting group is introduced with di-tert-butyl dicarbonate
Removed by brief treatment with trifluoroacetic acid

20. Peptide Coupling
Amides are formed by treating a mixture of an acid and amine with dicyclohexylcarbodiimide (DCC)

21. 26.11 Automated Peptide Synthesis: The Merrifield Solid-Phase Technique

22. 26.13 Protein Structure
The primary structure of a protein is simply the amino acid sequence.
The secondary structure of a protein describes how segments of the peptide backbone orient into a regular pattern.
The tertiary structure describes how the entire protein molecule coils into an overall three-dimensional shape.
The quaternary structure describes how different protein molecules come together to yield large aggregate structures