Ch 10: Nitrogen- and Phosphorus-Containing Compounds (Kaplan)

Question 1

To synthesize amino acids in vivo, what process starts with an aldehyde, and potassium cyanide (KCN), and produces an aminonitrile in the 1st step?

Answer 1

the Strecker synthesis

p. 239

Question 2

What is a nitrile group?

Answer 2

A C triple bonded to a N atom.

p. 239

Question 3

In step 2 of the Strecker synthesis, an amino acid is generated from the aminonitrile. This process can be performed in aqueous acid and accelerated by the use of heat. Since the starting material is a planar carbonyl-containing compound, the product is a _______ mixture.

Answer 3

racemic; both L- and D- amino acids are generated.

p. 240

Question 4

The Gabriel synthesis is also known as _______-_____ synthesis and it also produces a _______ mixture.

Answer 4

malonic-ester

racemic

p. 241

Question 5

Strecker synthesis is a condensation reaction (formation of _____ from a carbonyl-containing compound and ammonia, with loss of water), followed by nucleophilic addition (of the nitrile group), followed by hydrolysis.

Answer 5

imine

p. 248

Question 6

Gabriel synthesis proceeds through 2 _____ reactions, hydrolysis, and decarboxylation.

Answer 6

S_N2

p. 248

Question 7

What are the 4 main reactants in Gabriel synthesis of an amino acid?

Answer 7

1. potassium phthalimide
2. diethyl bromomalonate
3. alkyl halide
4. water

p. 248

Question 8

In a biochemical context, phosphoric acid is sometimes referred to as a phosphate group or _________ ________. At physiological pH, inorganic phosphate includes molecules of both hydrogen phosphate (HPO₄^2-) and dihydrogen phosphate (H₂PO₄^-).

Answer 8

inorganic phosphate (P_i)

p. 243

Question 9

pyrophosphate (P₂O₇^4-) is known as an….

Answer 9

…ester dimer of phosphate.

Note that in aqueous solution, it will likely degrade into inorganic phosphate.

p. 244

Question 10

Why is phosphoric acid such an excellent buffer?

Answer 10

Because it has three hydrogens with pK_a values that span nearly the entire pH scale

p. 244