Chapters 3, 4

Question 1

What is an oxidizing agent?

Answer 1

An oxidizing agent is a molecule with two or more highly electronegative atoms directly bonded together.
ex: HN03, 03, HClO4

Question 2

what position are most non-hydrogen groups favored in cyclohexane chairs? why?

Answer 2

In cyclohexane chair conformations, most non-hydrogen groups are most stable when in the EQUATORIAL position because there is minimal steric crowding at this position

Question 3

What happens if a molecule is described as having unchanged stereoconfiguration ?

Answer 3

The molecule should be chiral and have sp3 hybridization

Question 4

What are the properties for chair conformation ?

Answer 4

Chari conformation :
- allow all sp3 hybridized ring carbons to have a tetrahedral geometry.

Question 5

What conditions should hydrogens be nucleophilic ?

Answer 5

nucleophilic hydrogens are actually strong bases.
-(nucleophilic usually means it has some degree of negative charge)

Question 6

Which compounds undergo reduction with LIALH4? Which compounds don’t ?

Answer 6

Aldehydes, ketones and ester undergo reduction with LIALH4
-Acetals do NOT undergo reduction with LIALH4

Question 7

what is an example of a strong electrophile (aka lewis acid)

Answer 7

FeBr3

Question 8

What are examples of good nucleophiles ?

Answer 8

Iodide, carbons in Grignard reagents, and OH- (due to negative charge) are good nucleophiles

Question 9

What are properties of lewis acids ?

Answer 9

A Lewis acid is a molecule that can ACCEPT a pair of nonbonding electrons. These molecules can be recognized easily because they always have a positive charge and/or an incomplete octet.
Ex; BF3

Question 10

what type of compounds are usually in most stable chair configurations?

Answer 10

1,4 trans (that has both substituents on equatorial positions)

Question 11

what are important properties of meso compounds ?

Answer 11

Meso compounds
- does not rotate plane polarized light
-internal plane of symmetry
-has a mirror image identical to it

Question 12

what is the name of compound that rotates plane polarized light in clockwise direction ?

Answer 12

dextrorotatory (measured in positive degrees)

Question 13

what is the name of compound that rotates plane polarized light in counterclockwise direction ?

Answer 13

Levorotatory (measured in negative degrees)

Question 14

what is resolution of enantiomers?

Answer 14

When a racemic mixture is separated by chemical means, it leads to isolation of enantiomers.

Question 15

what are the most stable conformations for compounds in Newman projections ?

Answer 15

most stable conformations :
single bonds in staggered conformation is more stable than eclipsed (due to steric repulsion)
-Conformations which put the largest substituents in an anti (180° apart) arrangement are more stable than those in a gauche (60° apart) arrangement.

Question 16

How do you determine acidity of molecules?

Answer 16

look for electron withdrawing groups (like NO2, being stronger EWG and CN)
the closer the EWG is to carbonyl, the more acidic (as it stabilizes conjugate base through residence)
-also the more electronegative is an atom is and closer to carbonyl, the greater the inductive affect which increases acidity

Question 17

what determines level of heat of combustion ?

Answer 17

Ring strain. Molecules with great ring strain will have highest energy, and hence higher level of heat of combustion

Question 18

What are IUPAC rules for naming structures ?

Answer 18

When naming hydrocarbons, the longest linear carbon chain determines the root word
- Also, alcohols are a higher priority over halogens,
- substituents are placed in alphabetical order

Question 19

What kind of chair confirmation is most stable?

Answer 19

a chair with no angle strain or torsional strain (eclipsing Hydrogens)

Question 20

How do you determine stability of molecule if there is no resonance ?

Answer 20

the carbon substitution is used to determine the stability if there is no resonance
Since alkyl groups are electron donating, the least substituted carbanion is the most stable.

Question 21

What is the formula for degree of unsaturation ? What is DOU for C14H12?

Answer 21

degree of unsaturation is given by the formula (2C + 2 - H)/2, where C is the number of carbon atoms and H is the number of hydrogen atoms.
ex: C14H12 contains (28 + 2 - 12)/2 = 9 units of unsaturation.

Question 22

How do you determine basicity by electronegativity ?

Answer 22

The Less Electronegative atom is more basic

Question 23

which structures have large amounts of ring and torsional strain ? Which have least amount?

Answer 23

Cyclopropane and cyclobutane have a great amount of ring strain
-cyclohexane has no ring strain (the best)
-cyclopentane has little ring strain

Question 24

a