Chem 40A
Practice Midterm I
Fall 2020



Q1_________(-- points)


Q2_________(- points)


Q3_________(-- points)


Q4_________(-- points)


Q5_________(-- points)


Q6_________(-- points)



Q7_________(-- points)



Q8_________(-- points)




Total_________(150 points)



If you write the exam in pencil or erasable pen, you give up your right to any kind of regrade.

Name_______________________

PID_________________________

1. Functional Groups (-- points). Circle the functional groups present in the following molecules and give
their names.













2. Conformational Isomerism (-- points). Draw the following molecules in Newman projections with
respect to the bond indicated. Indicate whether they are staggered or eclipsed forms.

A. The most stable conformational isomer of 2,5-dimethylhexane around the C3-C4 bond.

















b. The least stable conformational isomer of 2,5-dimethylhexane around the C3-C4 bond.
























c. The most stable conformation of 1,2-dichloroethane





3. Structural Description (-- points). Answer the questions below with reference to the structure of
Cortisone. Be clear with your answers.



a. How many carbon atoms are present?
b. Indicate which atoms are sp2-hybridized (assume oxygen is hybridized)
c. Draw in and label all tertiary hydrogens
d. Indicate which carbons have 4 different substituents attached to them



4. Isomerism (-- points). Please be explicit, drawing out all of the atoms, including hydrogens.


a. Draw all of the structural isomers of C4H8O that do not contain a multiple bond.
(hint: there are more than 7).



















b. Draw all of the structural isomers of molecular formula C5H12O that contain an alcohol
functional group. (hint: there are more than 5).





















5. Nomenclature (-- points).


a. Give the IUPAC name of each of the following compounds








b. Draw structures for the following compounds.


2-methyl-2-bromopentane








3,4,5-trimethyloctane







Two Isomers of heptabromopropane

6. Structural Puzzles (-- points). Please include all hydrogen atoms in your drawings.

a. Draw the structure of a compound of formula C6H12 that contains only primary hydrogens.

































b. Draw a compound of molecular formula C5H10 that contains only secondary hydrogens









7. Resonance in Organic Chemistry (-- points).

A. Draw all the valid resonance forms of the ion below.




At what sites can this ion react with an electrophile? Indicate clearly by placing a small box
around the sites.



B. Draw all the valid resonance forms of the ion below.





At what sites can this ion react with a nucleophile? Indicate clearly by placing a small box
around the sites.












8. Challenge Question (-- points).

Draw a reasonable mechanism for the following reaction:





This reaction is unusually fast. Why is that?




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