Foothill.edu

Which of the compounds shown can form hydrogen bonds with other identical molecules? Explain each case. Ans: 2, 4, 5. All have H atoms attached to O and N. Practice writing the systematic names in each case:
1. Methyl acetate
2. 2-Methylpropanoic acid 3. N,N-Dimethylacetamide 4. N- 2. Number all carbons and label accurately the glycosidic links. Circle and label any anomeric carbon centers. Is this molecule a reducing sugar? Why or Why not? C1 is anomeric carbon center. This is a reducing sugar as C1 (arrow pointing) of β-D-Glucose is a
hemiacetal.

Chemical Reactions. For each reaction explain in words what
happened. Write the name of each reactant/product as applicable.
1. Write the products of hydrolysis of Lactose. Use structure from previous page.
As shown in class. Lactose is a disaccharide with a D-Glucose unit and a D-Galactose
unit which are the products of hydrolysis.
2.
a. Recognize that starting molecule is a ketone. b. Ketones give 20 alcohols on reduction. 2nd set using framework only. 3. No Reaction! Ketones hate oxidations!!! When it happens, it kills them. (shown using frames) Ethyl butanoate is an ester. When an Ester undergoes hydrolysis with a base present it gives the carboxylate salt of the acid and the alcohol. 5. Note the difference between acid and base hydrolysis of an ester. No carboxylate salts produced in acid hydrolysis , just the acid and the alcohol.
Pentanal is an aldehyde. Aldehydes convert to carboxylic acid on oxidation. Another O
atom is gained by the carbonyl carbon in oxidation.
In Reduction two new H atoms are added. The C=O bond is gone. The result is an
alcohol.
When you write the ionic form of an acid, you will need to remove the H atoms from the –OH groups. The ionic form is also the named as the ‘ –ate’ ion. Acetic acid is the missing item. In lab, we will use acetic anhydride (the water-free form of acetic acid) to make Aspirin. This is an esterification reaction. The carboxylic acid group –COOH on Carbon 1 remains unchanged. Note the change in Carbon 2. 9. Write the formula of N-Methylbutanamide. Write the products of hydrolysis of this amide. 10. Write a reaction between acetaldehyde and ethanol. What happens to this reaction when excess ethanol is used. A hemiacetal
An acetal
Y u do NOT need to know how to name hemiacetals and acetals. The names on this example are provided as a reference only. A –OR group where R is is an alkyl component is called an alkoxy group.
When R = -CH2CH3 it is an ethoxy group. This is “acetal”.
A few facts of interest:

In the liver, the enzyme alcohol dehydrogenase converts ethanol into acetaldehyde, which
is then further converted into acetic acid by acetaldehyde dehydrogenase.
People belonging to certain ethnic groups have a mutation in their alcohol dehydrogenase
gene that makes this enzyme quite effective at converting ethanol to acetaldehyde.
A out half of such people also have a form of acetaldehyde dehydrogenase that is less effective at converting acetaldehyde to acetic acid. This combination causes them to suffer from the alcohol flush reaction, in which acetaldehyde accumulates after drinking, leading to severe and immediate hangover symptoms. 11. Important questions on Stereoisomers and Optical Activity. From textbook. 22.32, 22.33, 22.37, 22.38, 22.39, 22.41, 22.42, 22.43, 22.44, *22.85 • Know that there are 2n number of stereoisomers in a molecule with ‘n’ number of • Distinguish between diastereomers and enantiomers (using Fischer drawing) • Know that Meso structures are optically inactive and how to identify them. • Enantiomers rotate plane polarized light in equal but opposite directions. • Some drugs are FDA approved to be marketed as racemic mixtures. It is not cost effective to separate the enantiomers. Racemic: Omeprazole (Prilosec) and Single-enantiomer: esomeprazole (Nexium) is one example. You do not need to memorize formulas to calculate specific rotation [α]

Source: http://www.foothill.edu/attach/psme/PQ_CH%2016,17,22_KEY.pdf