Notes10

Question 1

molecular architecture

Answer 1

structure of a molecule

Question 2

molecular dynamics

Answer 2

conformational analysis. rotation around C single bonds

Question 3

molecular transformations

Answer 3

chemical reactions

Question 4

reaction profile

Answer 4

free energy (y) vs. reaction progress (x)

Question 5

transition state

Answer 5

• a bond is being form almost same time as breaking another one
• always found at reaction profile max
• signified with double dagger

Question 6

reaction intermediate

Answer 6

• energy min on reaction profile

- reactive but stable until hit by something

Question 7

two ways covalent bonds can break

Answer 7

-homolytic and heterolytic cleavage

Question 8

homolytic cleavage

Answer 8

• formation of free radicals
• each atom gets one electron from the bond
• half arrow

Question 9

heterolytic cleavage

Answer 9

• formation of ions
• one atom keeps both bonding electrons
• full headed arrow

Question 10

positively charge carbon

Answer 10

carbocation

Question 11

bond dissociation energy

Answer 11

energy required to break bond homolytically

Question 12

factors that stabilize reaction intermediates

Answer 12

• resonance effect
• hyperconjugation/inductive effect
• combined effects: tie-breaker
• localized charges

Question 13

hyperconjugation

Answer 13

extra stability offered when sp2 carbocation positioned next to an sp3 carbon. the more alkyl groups, the better

Question 14

vinyl carbocation

Answer 14

two sp2 carbons, one missing a bond. no-electrons in hybridized sp2. NOT STABLE

Question 15

free radical reactions major steps

Answer 15

• initiation
• propagation
• termination

Question 16

rate limiting step

Answer 16

associated with the highest activation energy

Question 17

termination step

Answer 17

destroy remaining free radicals

Question 18

hammon postulate

Answer 18

infer transition state structure from the two closest reactants and products

Question 19

transition state in exothermic reaction…

Answer 19

occurs early on

Question 20

localized charges on reaction intermediates include…

Answer 20

• vinyl cation

- methyl cation

Question 21

combined effects

Answer 21

resonance structures stabilize more than hyperconjugation

Question 22

organic synthesis

Answer 22

series of reactions with specific molecule as goal

Question 23

free radical bromination selectivity

Answer 23

highly prefers the most stable intermediate. why? chlorine has much higher rxn rate

Question 24

bromination most useful for

Answer 24

tertiary, allylic, and benzylic halides. PREFERS MOST STABLE INTERMEDIATE

Question 25

allyl

Answer 25

3xsp2 C in a row. one carbon “next to double bond” is missing bond but has the electrons.

Question 26

vinyl vs allyl

Answer 26

vinyl = C on double bond
allyl = C one away from double bond

Question 27

NBS

Answer 27

• n-bromosuccinimide

- specifically used to brominate at allylic and benzylic positions

Question 28

allylic anion

Answer 28

methylene bridge (sp3 anion) attached to vinyl group