Basic Concepts

Question 1

Does SH or OH has the more acidic proton?

Answer 1

SH because Sulfur is bigger in size than O, which means it stabilizes the negative charge better when deprotonating it.

Question 2

If a compound is a weak conjugate base, is it a strong or weak acid?

Answer 2

Strong acid

Question 3

What are constitutional isomers?

Answer 3

They are compounds that have the same molecular formula, but different order of connectivity of atoms.

Question 4

What are stereoisomers?

Answer 4

They are compounds that have the same molecular formula and order of connectivity of atoms, but they differ in the spatial arrangement of the atoms. An example would be cis and trans isomers.

Question 5

What are configurational isomers?

Answer 5

Isomer which are either cis/trans (disubstituted alkenes) or E/Z (tri, tetra-substituted alkenes).

Question 7

Compounds that are (chiral/achiral) are optically active.

Answer 7

Chiral

Question 8

How many enantiomers can a chiral compound have?

Answer 8

Only 1

Question 9

What are the three possible ways to draw an enantiomer of a compound?

Answer 9

1. Change the dashes to wedges or vice versa. Keep the molecule the same.
2. Imagine putting a mirror underneath the molecule and drawn the mirror image. Keep the dashes/wedges the SAME.
3. Imagine a mirror next to the molecule and draw the mirror image of that. Keep the wedges/dashes the same.

Question 10

Difference in characteristics of enantiomers

Answer 10

-They have the same physical properties EXCEPT smell
-They have same # for specific rotation, but opposite magnitude. One is positive the other is negative

Question 11

A compound that has a positive specific rotation is called (dextrorotatory/levorotatory).

Answer 11

Dextrororatory

Question 12

A compound that has a negative specific rotation is called (dextrororatory/levorotatory).

Answer 12

Levorotatory

Question 13

What is the specific rotation of a molecule?

Answer 13

It it the observed rotation that the molecule presents when put through a polarimeter and is measured under standard conditions of a concentration of 1g/mL and pathlength of 1 dm (note that 10 cm = 1dm).

Question 14

What is a meso compound?

Answer 14

a superimposable image of a compound that has internal symmetry making the WHOLE compound achiral, but still has >1 chiral centers
-Not optically active
-A compound with a plane of symmetry and R/S or S/R on for the chiral centers

Question 15

Comparing a meso compound in a fischer projection vs bond line

Answer 15

-Fischer: rotate all the groups so that the top and bottom of the fischer have the same group, then look for plane of symmetry
-Bond-line: rotate the single bonds or determine if configurations are R/S

Question 16

Are these enantiomers or identical meso compounds?

Answer 16

-First, there is NO plane of symmetry bc one chiral center has a wedge, other has a dash
-Compounds have opposite configurations, 1st one is S/S, 2nd is R/R
Therefore, the compounds are enantiomers

Question 17

What is a racemic mixture?

Answer 17

It is a solution that contains equal anoints of both enantiomers, rendering it optically inactive (having a net rotation of 0 degrees).

Question 18

How can enantiomers be separated in a solution?

Answer 18

A resolving agent ( a single enantiomer of another compound) can be added to the solution to produce two pairs of diastereomeric salts. Those diastereomer salts can then be separated based on physical properties and converted back to the original enantiomers by adding a base.

Question 19

A meso compound is (chiral/achiral).

Answer 19

Achiral

Question 20

True or false:
Any compound in which you can draw an internal plane of symmetry (vertical or horizontal) and both sides look the same, would make it a meso compound and achiral.

Answer 20

True

Question 21

When determining the hybridization of an atom, do you take into account a delocalized lone pair on that atom?

Answer 21

No, delocalized lone pairs occupy p orbitals which aren’t counted for the hybridization of an atom. Just ignore the lone pair to determine the hybridization.

Question 22

Bronsted Lowry acids and bases deal with the ________.

Answer 22

Transfer of protons.
A bronsted acid is a proton donor.
A Bronsted base is a proton acceptor.

Question 23

What happens during a proton transfer mechanism part?

Answer 23

A base grabs a proton from an acid. This mechanism always involves at least 2 arrows.

Question 24

The equilibrium of a reaction favors the side with the (stronger/weaker) acid.

Answer 24

Weaker acid (higher pKa value) or more stable base

Question 25

A compound that accepts a pair of electrons is called a (Lewis Acid/Lewis Base).

Answer 25

Lewis Acid

Question 26

A compound that donates a pair of electrons is called a (Lewis Acid/Lewis Base).

Answer 26

Lewis Base

Question 27

Give examples of Lewis acids

Answer 27

AlBr3, AlCl3, H3O+, BF3

Question 28

Give examples of Lewis based

Answer 28

Ketones, esters, Br2

Question 29

When comparing an sp hybridized proton on a carbon atom vs. an sp3 hybridized proton on a N atom. Which one is more acidic?

Answer 29

The sp hybridized proton on the carbon. Even though N is more electronegative, the sp orbital on the C outweighs the electronegativity of N, making the proton more acidic.

Question 30

Basic Bitches steal protons. (AKA Bronsted Bases steal protons).

Answer 30

Neumonic for Bronsted bases taking protons.

Question 31

How does the solvent effect explain the effect of steric hinderance on the stability of the molecule as a solvent?

Answer 31

The more alkyl substituents on a compound, the less stable the conjugate base of the compound is. This makes it less likely to interact with solvent molecules What we want is a very stable conjugate base which makes a strong acid.

Question 32

How does branching of alkanes affect the stability of the compound?

Answer 32

Branched alkanes are lower in energy (more stable) than straight chain alkanes. Branched alkanes have a lower heat of combustion.

Question 33

What is the difference between conformational isomers and configurational isomers?

Answer 33

Confirmational isomers are molecules that differ due to rotation of a single bond in the molecule. Examples include rotating the substituents in a Newman Projection, having two methyl groups which were anti, now become gauche upon rotation. Configurational isomers are molecules with DOUBLE BONDS that can either be categorized as cis/trans or E/Z. Remember double bonds can’t be rotated, so the bonds would have to break.

Question 34

Chirality is dependent upon rotational or reflectional symmetry?

Answer 34

Reflectional symmetry because the compounds that have a plane of symmetry are achiral.

Question 35

If there are two lines drawn on a reaction coordinate diagram, how can we interpret which line is thermodynamically favorable and which line is kinetically favored?

Answer 35

The line that has a lower activation energy is kinetically favored. The line with products that are lower in energy (more stable) is thermodynamically favored.

Question 36

When are irreversible reaction arrows generally used for acid/base reactions?

Answer 36

When the pKas between the two acids differ by more than 10 units. For example, a pKa of 5 and pKa of 20 would constitute an irreversible reaction.

Question 37

True or false: If a bond is higher in energy, it will also require less energy to break it.

Answer 37

True

Question 38

Bonds which are more stable and stronger, have (more/less) potential energy.

Answer 38

Less

Question 39

Conformational isomers

Answer 39

Molecules that are different due to rotation around single bonds (Ex: different Newman projection conformations of butane: staggered and eclipsed) *Have different magnitude of optical rotation

Question 40

Alpha vs. beta carbon in a molecules

Answer 40