This preview shows page 1. Sign up to view the full content.
Unformatted text preview: THIS IS THE BEGINNING OF THE SHORT ANSWER SECTION OF THE EXAM. (7 pts.) The questions below pertain to the following reaction: A H C C C H H C C O OH H OH OH B H C C H H H C C C O O H OH OH CH2OH
H C C C H H C C O H OH OH H H O H C C C C C O H OH OH O CH2OH CH2OH CH2OH (1 pts.) What type of reaction is this? isomerization (occurs during caramelization) (3 pts.) Show in the space above the resonance structure that results from loss of the circled proton on Molecule A. see resonance hybrid structure above (2 pts.) How does this resonance structure lead to formation of Molecule B? The resonance contributing structure on the right has a negative charge on the C3 carbon (it is a carbanion). A proton (H+) adds to that location to form molecule B. (1 pts.) What type of molecule is Molecule B? a dicarbonyl page 10 (8 pts.) The following questions pertain to the structure below:
CH2OH O OH HO OH O OH OH CH2OH O OH (1 pts.) What is the specific name of this molecule? (1 pts.) What is the glycosidic linkage in this molecule? β-D-maltose α[1,4] (3 pts.) Is this molecule a reducing sugar? Use the structure above to explain why or why not. Yes, it is a reducing sugar, because the –C-O- bond can easily break at the position above, allowing mutarotation. Formation of the open chain exposes a carbonyl group which can oxidize, allowing this sugar to reduce other molecules. (3 pts.) Explain how this molecule is produced from corn starch. Starch is a glucose polymer with α[1,4] glycosidic linkages. Hydrolysis causes the breakage of these bonds, and if this occurs at a location that is two bonds in from the polymer's end, maltose is formed (i.e. two joined subunits come off during hydrolysis). page 11 ...
View Full Document
This note was uploaded on 10/22/2010 for the course FST 100A taught by Professor Dungan during the Fall '08 term at UC Davis.
- Fall '08