Amino Acids, Amides, and Chirality

Question 1

What is the general structure of an alpha amino acid?

Answer 1

R O (move along)
H - I =
N - C - C
H - l -
H OH

Question 2

What is the general formula of an alpha amino acid?

Answer 2

RCH(NH2)COOH.

Question 3

What is amino acid?

Answer 3

An organic compound containing both amine, NH2, and carboxylic acid, COOH, functional groups.

Question 4

What is an alpha amino acid?

Answer 4

Where the amine group is attached to the alpha carbon atom (the second carbon atom, next to the carboxyl group).

Question 5

How do alpha amino acids differ?

Answer 5

They each contain different R groups (side chains) attached to the alpha carbon atom.

Question 6

What are the other amino acids?

Answer 6

Less common ones where the amine group is connected to the B-carbon atom (the third carbon) and the Y-carbon atom (the fourth carbon).

Question 7

What is the equation for the amine groups in amino acids reacting with acids?

Answer 7

Amino acid + Acid = Ammonium salt + Ion.

Question 8

What is an example reaction of the amine group in amino acids reacting with acids (2-aminopropanoic acid + HCl)?

Answer 8

2-aminopropanoic acid + HCl = Ammonium salt + Cl-.

Question 9

How are ammonium salts displayed when the amine group in amino acids reacts with acids?

Answer 9

With the added H on the N and a positive charge above the N.

Question 10

What is the equation for the carboxylic group in amino acids reacting with aqueous alkalis?

Answer 10

Amino acid + Aqueous alkali = Salt + H2O.

Question 11

What is an example reaction of the carboxylic group in amino acids reacting with aqueous alkalis (glycine+ NaOH)?

Answer 11

Glycine + NaOH = Sodium salt + H20.

Question 12

How are metal salts displayed when a carboxylic group in an amino acid reacts with aqueous alkalis?

Answer 12

The O from the OH on the carboxylic acid turns into O- then the metal attached to it as a positive replacing the H atom, e.g. O- Na+

Question 13

What is the equation for amino acids to be esterified? Catalyst?

Answer 13

Amino acid + Alcohol + H+ = Ester + H2O. With concentrated H2SO4 and heating.

Question 14

How does esterification of an amino acid happen?

Answer 14

The amino acid is reacted with excess alcohol and a small amount of concentrated H2SO4. The COOH group is esterified, producing an ester.

Question 15

What does the ester product look like when it has been reacted with an amino acid and an alcohol?

Answer 15

The amine region has remained the same but the H from the OH on the COOH group has been replaced with the alkane (from the alcohol).

Question 16

What is an example reaction of an amino acid undergoing esterification?

Answer 16

Serine + Ethanol + H+ = Ester + H20.

Question 17

What are amides the product of?

Answer 17

The reactions of acyl chlorides with ammonia and amines.

Question 18

What are the primary, secondary, and tertiary amides?

Answer 18

• Primary: one carbon bonded to the nitrogen.
• Secondary: two carbons bonded to the nitrogen.
• Tertiary: three carbons bonded to the nitrogen.

Question 19

What are stereoisomers?

Answer 19

Compounds with the same structural formula but a different arrangement of atoms.

Question 20

What is another type of stereoisomerism?

Answer 20

Optical isomerism.

Question 21

What is optical isomerism?

Answer 21

Found in molecules that contain a chiral centre.

Question 22

What is a chiral centre?

Answer 22

A carbon that is attached to four different groups of atoms.

Question 23

What does the presence of a chiral carbon atom lead to?

Answer 23

The existence of two non-superimposable mirror image structures. These two molecules are known as optical isomers or entantiomers. For each chiral carbon atom, there is always one pair of optical isomers.

Question 24

What one alpha amino acid does not contain a chiral carbon atom?

Answer 24

Glycine.

Question 25

How do you indicate the chiral carbon atom?

Answer 25

By using an asterisk.

Question 26

How do you draw optical isomers?

Answer 26

By showing mirror images of one another (changing the sides of which the functional groups are on) and swapping the functional groups positions completely.