Name (PRINT!): ANSWER KEY

1. What is the molecular formula of each of the compounds below? [3 points each]
 
 

C₁₀H₁₆
 
 

C₈H₈O₃
 
 

C₈H₁₇N

C₁₃H₁₀N₂O₄
 
 

2. The connectivity formula for citronellol, the major component of citronella candles used to keep the mosquitoes away during summer, is given below.

(a) What is the condensed structural formula of citronellol? [4 points]

(CH₃)₂CHCH₂CH₂CH₂CH(CH₃)CH₂CH₂OH

OR (CH₃)₂CH(CH₂)₃CH(CH₃)(CH₂)₂OH

(b) Draw the line formula for citronellol. [4 points]

3. (a)tert-Butyl alcohol is an important reagent and solvent in organic chemistry. It has the molecular formula C₄H₁₀O. It is an alcohol, with one unique carbon atom and the other three carbon atoms equivalent to each other. Draw the correct Lewis structure for tert-butyl alcohol. You may use lines to represent electron-pair covalent bonds. [5 points]

(b) Chloroacetamide is an amide with the molecular formula C₂H₄ClNO. The chlorine atom is not attached to nitrogen. Draw the correct Lewis structure for chloroacetamide. You may use lines to represent electron-pair covalent bonds. [5 points]

(c) The tropylium ion, C₇H₇⁺ is an ion of particularly great theoretical importance in organic chemistry. Each of the seven carbon atoms has one hydrogen atom bonded it, and the molecule has a cyclic structure with a seven-membered ring. Draw a correct Lewis structure for the tropylium ion. You may use lines to represent electron-pair covalent bonds. [5 points]

(d) Draw the correct Lewis structure for sodium dimethylamide, C₂H₆NNa, a strong base used in synthetic organic chemistry. All six hydrogen atoms of this compound are bonded to carbon atoms.

[5 points].

Remember: This compound is IONIC -- the sodium is present as Na⁺. You lost points if you wrote a covalent bond to sodium.

4. Circle and name the functional groups is the neurotransmitter molecule below [10 points].

5. Describe the shape around each of the circled atoms (A,. B, C, D, E) in the morphine molecule, whose structure is given below. [10 points]

A: bent                            B: trigonal planar

C: trigonal pyramid         D: tetrahedral

E: trigonal planar
 
 

6. Complete each of the following reactions. Based on the pK_a values in the Table below, decide if the reaction will proceed to completion as written, or if the reaction will not proceed as written. [5 points each]

pK_a values:

alcohols 15-18                             aldehydes 26-30 (O=C­C­H)
alkanes 45-60                             alkenes 42-45 (C=C­H)
alkynes 26-30                             amides 15-18 (N­H)
amines 33-38 (N­H)                 aromatic hydrocarbons 42-45
carboxylic acids 4-6                     esters 26-30 (O=C­C­H)
ethers 45-60                                 ketones 26-30 (O=C­C­H)
nitriles 26-30 (NC­C­H)         phenols 11-12
thiols 11-12.

The reaction is between a carboxylic acid (pK_a 4-6) and the conjugate base of an amine (pK_a 33-38)

The reaction will proceed to completion as written.

The reaction is between an aromatic hydrocarbon (pK_a 42-45) and the conjugate base of an alcohol (pK_a 15-18)

The reaction will not proceed to completion as written.
 
 

The reaction is between a phenol (pK_a 11-12) and the conjugate base of an alcohol (pK_a 15-18)

The reaction will proceed to completion as written.
 
 

7. Consider the following two orbitals .

(a) What is the principal quantum number of the orbital on the left? [2 points] 4

(b) What is the azimuthal quantum number of the orbital on the left? [2 points] 2

(c) What is the principal quantum number of the orbital on the right? [2 points] 5

(d) What is the azimuthal quantum number of the orbital on the right? [2 points] 1
 
 

8. Identify the nucleophile and the electrophile in each of the following reactions [5 points each]

Electrophile: ketone       Nucleophile: cyanide anion, CN^-

Note: If the cyanide anion was not specified, you did not get full credit: the lithium is a spectator ion.

Electrophile: B        Nucleophile: N
 

Electrophile: cation (C⁺ has just 6 electrons around it)        Nucleophile: water