CHEM120 Exam 3

Chapter 15 & 16

What is the general formula for carbohydrates?

C_nH_2nO_n

What is the difference between a monosaccharide, disaccharide, and polysaccharide?

Mono = 1 sugar, di = 2 sugars linked, Poly = many sugars linked

What are the two functional groups in all monosaccharides?

Hydroxyl (-OH) and carbonyl (C=O)

How do you determine if a sugar is a D or an L?

Look at the penultimate carbon; OH on the right = D, left = L

penultimate carbon

the second-to-last carbon atom in a carbon chain

Enantiomers vs Diastereomers

Enantiomers = mirror images
Diastereomers = non-mirror stereoisomers

Define Chiral Carbon

Carbon with 4 different groups attached

How are enantiomers drawn in a Fisher Projection?

As mirror images with opposite configurations at all chiral centers

What reaction creates a cyclic monosaccharide?

Intramolecular reaction forming a hemiacetal (C=O + OH)

a- vs B-anomer difference

a = OH opposite side from CH₂OH; B = OH same side

What is the anomeric carbon

The carbon derived from the carbonyl carbon during ring formation

D-Glucose

D-fructose

D-Ribose

D-Galactose

Functional Group of Carboxylic Acids

-COOH

Functional group of Esters

-COOR

Suffix for acids

-oic acid

Suffix for esters

-oate

how to name esters?

Alkyl + Acid part (-oate)
Example: Methyl Benzoate

Why do carboxylic acids have high boiling points?

Strong H-bonding and dimer formation

Can esters hydrogen bond with each other

No. Therefore they have a lower boiling points

Solubility trend for carboxylic acids

small chains = soluble; large chains = less soluble

What is saponification?

Base-catalyzed ester hydrolysis producing soap

Esterification reaction

Acid + Alcohol <> ester + water (H+ catalyst)

Acid hydrolysis of an ester

Ester + H₂O → acid + Alcohol

Base hydrolysis of an ester

Ester + NaOH → carboxylate salt + alcohol