DAT: OCHEM (random review) Exam Actual
Exam Questions and Correct Answers 2026
GRADED A+
D
O
N
O
T
C
O
PY
What determines priority in assigning R/S?
Atomic number
What assigns priority in assigning E/Z?
Atomic number
______ are an electron rich species and donates to an electron
poor species known as a _________.
,nucleophile (most anything negative) electrophile (electron
poor so wants badly, some e- deficiency)
An increase of nucleophilicity is a INCREASE/DECREASE of
electronegativity. Decrease polar PROTIC solvents
Polar Protic solvents are polar solvents that have at least 1
hydrogen that is connected directly to a particular
electronegative atom such as O-H, N-H, etc., and are capable of
forming hydrogen bonds with the solute.
D
O
Examples of polar protic solvents are water, ethanol, ammonia,
HF, acetic acid, etc.
N
polar APROTIC solvents
O
Aprotic solvents are solvents in which no hydrogen bonding
T
takes place or they neither donate nor accept the proton
C
(hydrogen). They have no charge, or their dielectric constant is
very low.
O
PY
For example, benzene ( C 6 H 6 ) , carbon tetrachloride ,
ACETONE, etc.
carbocation intermediate (REARRANGEMNTS)
unimolecular rate law (electrophile only)
two stepsnot stereospecific, chiral will produce racemic
mixture
,WWWeak base SN1
pentavalent transition state
bimolecular rate law one
step
stereospecific, chiral center results in inversion of
D
sterochemistry SN2
O
bimolecular rate law
N
creates double bond
O
MUST be antiperiplanar to occur (H and LG)
T
C
stereoselective (E major product) E2
O
unimolecular rate law (substrate only)
PY
two steps, carbocation intermediate (rearrangements
possible)
heat included to make E1 > SN1
WWWeak bases (HOH, ROH)
E1
, The MOST/LEAST nucleophilic molecule will be the
WEAKEST/STRONGEST base.
Nucleophilicity parallels basicity. Therefore, the MOST
nucleophilic molecule will be the STRONGEST or most reactive
base.
Negatively charged bases are more reactive than neutral ones.
If the negative charge of the base is stabilized by resonance, the
D
base will be more stable and thus less reactive.
O
NaH, DBN, DBU, LDA, t-BuOK, Triethylamine
are:WEAK/STRONG bases and STRONG/WEAK nucleophiles.
N
STRONG bases
O
WEAK nucleophiles (NEUTRAL)
T
(E2)
C
RO-, HO-, MeO-, EtO- are STRONG/WEAK bases and
O
STRONG/WEAK nucleophiles.
PY
STRONG bases
STRONG nucleophiles
Halogens, RS-, HS-, RSH, H2S, NaN3 are STRONG/WEAK bases
and STRONG/WEAK nucleophiles.
WEAK bases
STRONG nucleophiles
Exam Questions and Correct Answers 2026
GRADED A+
D
O
N
O
T
C
O
PY
What determines priority in assigning R/S?
Atomic number
What assigns priority in assigning E/Z?
Atomic number
______ are an electron rich species and donates to an electron
poor species known as a _________.
,nucleophile (most anything negative) electrophile (electron
poor so wants badly, some e- deficiency)
An increase of nucleophilicity is a INCREASE/DECREASE of
electronegativity. Decrease polar PROTIC solvents
Polar Protic solvents are polar solvents that have at least 1
hydrogen that is connected directly to a particular
electronegative atom such as O-H, N-H, etc., and are capable of
forming hydrogen bonds with the solute.
D
O
Examples of polar protic solvents are water, ethanol, ammonia,
HF, acetic acid, etc.
N
polar APROTIC solvents
O
Aprotic solvents are solvents in which no hydrogen bonding
T
takes place or they neither donate nor accept the proton
C
(hydrogen). They have no charge, or their dielectric constant is
very low.
O
PY
For example, benzene ( C 6 H 6 ) , carbon tetrachloride ,
ACETONE, etc.
carbocation intermediate (REARRANGEMNTS)
unimolecular rate law (electrophile only)
two stepsnot stereospecific, chiral will produce racemic
mixture
,WWWeak base SN1
pentavalent transition state
bimolecular rate law one
step
stereospecific, chiral center results in inversion of
D
sterochemistry SN2
O
bimolecular rate law
N
creates double bond
O
MUST be antiperiplanar to occur (H and LG)
T
C
stereoselective (E major product) E2
O
unimolecular rate law (substrate only)
PY
two steps, carbocation intermediate (rearrangements
possible)
heat included to make E1 > SN1
WWWeak bases (HOH, ROH)
E1
, The MOST/LEAST nucleophilic molecule will be the
WEAKEST/STRONGEST base.
Nucleophilicity parallels basicity. Therefore, the MOST
nucleophilic molecule will be the STRONGEST or most reactive
base.
Negatively charged bases are more reactive than neutral ones.
If the negative charge of the base is stabilized by resonance, the
D
base will be more stable and thus less reactive.
O
NaH, DBN, DBU, LDA, t-BuOK, Triethylamine
are:WEAK/STRONG bases and STRONG/WEAK nucleophiles.
N
STRONG bases
O
WEAK nucleophiles (NEUTRAL)
T
(E2)
C
RO-, HO-, MeO-, EtO- are STRONG/WEAK bases and
O
STRONG/WEAK nucleophiles.
PY
STRONG bases
STRONG nucleophiles
Halogens, RS-, HS-, RSH, H2S, NaN3 are STRONG/WEAK bases
and STRONG/WEAK nucleophiles.
WEAK bases
STRONG nucleophiles
