orgo 1 exam 2

3 types of strain that cycloalkanes can have

angle, torsional, steric

angle strain is caused by…

angles other than 109 degrees

torsional strain is caused by… (2 linked things)

loss of hyperconjugation, eclipsed Hs

steric strain is caused by…

atoms bumping into each other

can carbon-carbon bonds in rings rotate?

no

describe stereoisomer (3)

same molecular formula, same connectivity, different 3D arrangement of atoms

a ___ stereoisomer is when 2 of the same substituents are on the same side (up/up, down/down)

cis

a ___ stereoisomer is when 2 of the same substituents are on different sides (up/down, down/up)

trans

what is the most stable conformation of cyclohexane?

chair

in the chair conformation, all bond angles are…

109.5 degrees

in the chair conformation, are all bonds staggered or eclipsed?

staggered

does a non-substituted cyclohexane chair have any strain?

no

substituents on a cyclohexane chair that stick straight up/down are…

axial

substituents on a cyclohexane chair that stick out on the sides are…

equatorial

a chair flip turns axial bonds…

equatorial

a chair flip turns equatorial bonds…

axial

a chair is more stable when its larger substituent is…

equatorial

what type of interactions occurs when a large substituent is axial?

1,3-diaxial

1,3-diaxial interactions are identical to _____ interactions

gauche

do ring flips change whether an isomer is cis or trans?

no

2 characteristics needed to be chiral

no mirror plane, not identical to mirror image

what is a constitutional isomer?

same molecular formula, different connectivity

what are enantiomers?

mirror image isomers

are enantiomers superimposable?

no

what are diastereomers?

non-mirror image isomers

in order to be chiral, a molecule would need a carbon attached to 4 ____ substituents

different

in a drawing, should wedge and dash bonds be on the same side?

yes

in order to “verify” that R/S configuration is correct, the lowest priority substituent should be attached via ____ bond

dash

how are double bonds interpreted in CIP prioritization rules?

2 single bonds to that atom

what type of bonds (wedge/dash) are the vertical bonds on a fischer projection?

dash

what type of bonds (wedge/dash) are the horizontal bonds on a fischer projection?

wedge

you can check the __/__ configuration of a fischer projection to make sure it matches the molecule

R/S

2 fischer projection translations that give the same molecule

rotate molecule 180 degrees in plane, exchange 3 substituents

enantiomers have the ____ melting point, boiling point, molecular weight, GC/MS, and IR spectra

same

enantiomers behave differently from each other when interacting with ____ environments

chiral

enantiomers behave differently from each other when interacting with plane polarized ___

light

the field of plane polarized light is aligned in ___ direction

one

a dextrorotatory (+) enantiomer will rotate the plane of polarization ______

clockwise

a levorotatory (-) enantiomer will rotate the plane of polarization ______

counterclockwise

1, 2, 3 clockwise is __ configuration

R

1, 2, 3 counterclockwise is __ configuration

S

____ ______ = specific rotation x path length x concentration (g/mL)

measured rotation

what is a racemic mixture?

50/50 ratio of enantiomers

the specific rotation of enantiomers will have the same magnitude, but different ___

sign

percent of the sample that is the isomer in excess

enantiomeric excess

2 situations that could give an optical rotation of 0 (optically inactive)

achiral compound, racemic mixture

how to calculate maximum number of possible stereoisomers?

2^ # of chiral centers

what is a meso compound?

compound with 2+ chiral centers that is achiral

are alcohols more likely to be acidic or basic (when attached to aromatic rings)?

acidic

what does a strong acid become after donating a proton?

weak conjugate base

what does a strong base become after accepting a proton?

weak conjugate acid

how many “effective hydrogens” does oxygen count as?

0

how many “effective hydrogens” does a halogen count as?

1

how many “effective hydrogens” does nitrogen count as?

-1

______ = [(2C + 2) - effective H] / 2

degree of unsaturation

how many degrees of unsaturation does each ring in a molecule count as?

1

how many degrees of unsaturation does each pi bond in a molecule count as?

1

to name alkenes, the double bond must be in the _____ chain and get the ____ number possible

parent, lowest

is a number for double bond needed when naming cycloalkenes? why?

no, assumed to be between carbons 1 and 2

can pi bonds be rotated without breaking?

no

in alkenes, high priority substituents on the same side (up/up, down/down) are __ configuration

Z

in alkenes, high priority substituents on different sides (up/down, down/up) are __ configuration

E

term for electron-rich species

nucleophile

term for electron-poor species

electrophile

are acids electrophiles or nucleophiles?

electrophiles

are bases electrophiles or nucleophiles?

nucleophiles

stronger acids have _____ pK_a values

smaller

stronger acids have ____ K_a values

larger

weaker acids have ____ conjugate bases

stronger

stronger bases have _____ conjugate acids

weaker

the equilibrium lies toward the side with the _____ acid

weaker

approximate pK_a of protonated alcohols, protonated water (H₃O⁺), HCl, HI, HBr

less than 0

approximate pK_a of carboxylic acids

5

approximate pK_a of protonated amines and phenols

10

approximate pK_a of regular alcohols and water

15

lewis bases must have an accessible…

pair of electrons

2 “sources” of accessible electron pairs

pi bond, lone pair

lewis acids must have an empty/emptiable ____

orbital

acids and what they do regarding protons and electrons

donate protons, accept electrons

bases and what they do regarding protons and electrons

accept protons, donate electrons

adding an electrophile to an alkene results in a _____ intermediate

carbocation