Chem. 30B Name _____ __KEY_________________

Exam #2 please print

April 21, 2003 75 min. 105 points

Please choose a random 4 digit number for on-line scores ___ ___ ___ ___ .

Remember it!

Model kits may be used. Some questions have more than one correct answer, but you may give only one. Avoid crowding your answers. Use the back if needed.

1. Fill in the blanks:

[2] a. The functional group that is hydrolyzed (broken down) when starch is digested is

acetal or glycoside.

[2] b. The opposite of a hydrolysis reaction is a condensation reaction .

[2] c. The most common sugar unit in the world is glucose .

[2] d. Maltose consists of glucose bonded to glucose

[2] e. The active ingredient in tobacco is nicotine. It belongs to the class of chemicals called alkaloids (& other correct answers)

[2] g. In terms of chemical reactions, the most important difference between an amine nitrogen and an amide nitrogen is amine N is basic; amide N is neutral

2. Draw one clear structural formula for each of the following:

a. [6] a Fisher projection of chiral secondary amine which has the formula C3H9ON	b. [5] a Haworth projection of beta-D-galactose
b. [5] a Fisher projection of a meso compound with the formula C4H10O4	c. [4] D-glyceraldehyde

4. Draw the structures of the major organic products of the following reactions.

a. [6]

d. [6]

5. [6] Is it possible for the two compounds below to hydrogen bond to each other. If "yes", draw a simple labeled sketch of the bonding. If "no", explain why not.

NO There is no O-H or N-H bond in either compound to be the hydrogen bond donor.

6. An organic compound X is not soluble in water. It dissolves in basic solutions such as NaOH(aq). The original compound precipitates out of solution when it is made acidic with hydrochloric acid. See the diagram below.

a. [4] In what family of compounds does X belong? Carboxylic acid

b. [5] Briefly explain why you chose this answer. Carboxylic acids are the only family of organic compounds that respond to base by becoming ionic and dissolving. Adding acid reverses this reaction, converting the ion back to a neutral molecule.

7. [8] Name the following compound.

8. [3] What is a non-reducing sugar? A sugar that does not reduce Benedictπs or Tollenπs reagent, In a reducing sugar the rings are ≥locked≤ with an acetal or ketal linkage rather than a hemiacetal.

[2] Name one: Sucrose

[5] Draw the chemical structure of any non-reducing sugar, not necessarily the one you named.

9. [5] a. In the following compound circle and label all of the acidic sites and all of the basic sites.

e. [5] Draw carefully placed arrows to each and every atom in the compound that can hydrogen bond to water.

10. [6] Honey is an aqueous solution containing a mixture of glucose and fructose. Describe the similarities and differences between the sugar in honey and ordinary table sugar (sucrose) in terms of a. their chemical structures and b. consequences for digestion.

A mixture is different from a compound.

Sucrose is a disaccharide of glucose bound to fructose in a single molecule. The mixture of glucose and fructose in honey contains two separate monosaccharides. .A disaccharide must be digested ≠ broken down to monosaccharides.

11. a. [4] Briefly describe the difference between amylose & amylopectin. b. [4] Draw a simple sketch.

c. [4] Would you expect there to be a substantial difference in the amount of energy (calories) that these two forms of starch would yield when eaten and completely digested? Explain. [=12]

a. Amylose is a linear polymer while amylopectin is branched.

b. see textbook

c. No difference in energy because after digestion they are both completely broken down to glucose.