Ochem Chapter 4 Alkanes, Alkyl Halides, And Substitution Rxns

Front 1

saturated hydrocarbons contain no...

Back 1

double/triple bonds
CH(n+2)

Front 2

primary carbon
secondary carbon
tertiary carbon
quaternary carbon

Back 2

CH3R
CH2R2
CHR3
CR4

Front 3

primary hydrogen
secondary hydrogen
tertiary hydrogen

Back 3

CH3R
CH2R2
CHR3

Front 4

as molecular weight increases the ___ increase/decreases

-MP
-BP
-Density

Back 4

increase

Front 5

branched molecules have reduced surface area and therefore lower/higher BP

Back 5

lower
-lower van der waals forces

Front 6

combustion

Back 6

alkanes + O2 --> CO2 and H2O + heat

Front 7

free radical halogenation
-diatomic halogens(Cl2)
-can be cleaved using...

Back 7

UV light or heat
aka initiation

Front 8

the halogen radicals become extremely reactive...

Back 8

begin propagation...
then end with termination when two radicals combine and end process

Front 9

the more stable the intermediate is....

Back 9

the more likely the reaction is to occur

Front 10

3>2>1>methyl for...

Back 10

stability of radicals

Front 11

bromine attacks to form more stable radicals while chlorine will attack to form less stable radicals

Back 11

know

Front 12

free radical chlorination yields mixtures of products...it is dependent on the number of hydrogens present

Back 12

know

Front 13

pyrolysis

Back 13

occurs when a molecule is broken down by heat
-commonly used to reduce the average molecular weight or heavy oils and increase the production of the more desirable volatile compounds

Front 14

disproportionation

Back 14

when radical donates a hydrogen to another radical and forms an alkene

Front 15

nucleophiles are ____ charged

Back 15

negatively (e- rich)

Front 16

electrophiles are ___ charged

Back 16

positively

Front 17

nucleophiles and basicity

Back 17

nucleophilic strength decreases
OR- > HO- > RCO2- > ROH > H2O

Front 18

nucleophile and size
protic solvents
aprotic solvents

Back 18

protic solvents:
large atoms tend to be better nucleophiles since they are more polarizable
CN- > I- > RO- > Br- > Cl- >F- > H2O

aprotic solvents : EN
- F- > Cl- > Br- > I-

Front 19

leaving groups

Back 19

best leaving groups are weak bases
-can accommodate and e- pair

Front 20

halogen leaving group order...

Back 20

I- > Br- > Cl- > F-

Front 21

Sn1 rxns

Back 21

unimolecular substitution

Front 22

unimolecular = rate of rxn depends only on ___ specie/s

Back 22

one

Front 23

SN1 rate determining step =

Back 23

dissociation of specie to form a stable carbocation

Front 24

SN1 involves __ step/s

Back 24

two

Front 25

SN1 require a/protic solvents

Back 25

polar protic solvents

Front 26

SN1 carbocation stability

Back 26

3 > 2 > 1 > methyl

Front 27

original substituent must be a ____ leaving group than the nucleophile

Back 27

better

Front 28

SN1 rxns DO/DO NOT require strong nucleophiles

Back 28

DO NOT

Front 29

carbocation acts as a strong electrophile

Back 29

know SN1

Front 30

rate of SN1 rxns

Back 30

slowest Rate determining step is formation of the carbocation
-dependent only on the concentration of the original molecule (1st order rxn)

Front 31

the rate of the rxn for SN1 does/does not depend on the concentration/nature of the nucleophile

Back 31

does not

Front 32

rate of rxn for SN1 can be increased by anything that accelerates the formation of the....

Back 32

carbocation

Front 33

structural factors: highly substituted alkyl halides are more/less stable

Back 33

more stable carbocation

Front 34

solvent effects: highly polar solvents better with ions

Back 34

know

Front 35

leaving group: weak bases dissociate more easily; make better leaving groups

Back 35

increase carbocation formation

Front 36

SN2 rxns

Back 36

bimolecular substitution

Front 37

SN2 involves a strong/weak nucleophile

Back 37

strong

Front 38

SN2 occurs in ___ step(s)

Back 38

one
-this one step is the rate determining step

Front 39

bimolecular means it involves 2 molecules

Back 39

know

Front 40

nucleophile attacks and displaces leaving group...aka...

Back 40

backside attack

Front 41

SN2 requires less hindered substrates

Back 41

methyl > 1 > 2 > 3

Front 42

transition state of SN2 =

Back 42

trigonal bipyramidal
SP2

Front 43

rate of SN2

Back 43

rate determining step involves substrate and nucleophile

Front 44

concentrations of both substrate and nucleophile will have an impact on the rate of the rxn

Back 44

know
-increasing concentrations increases likelihood of the rxn

Front 45

SN2 = 2nd order kinetics

Back 45

know

Front 46

SN1 stereochemistry

Back 46

carbocation intermediate = 120degree planar
-sp2 hybrid
-nucleophile can attack either top/bottom

Front 47

since it can attack from top/bottom...it will result in 2 products....

Back 47

loss of stereochemistry for SN1
-if original compound was optically active... the product will be a racemic mixture and not be optically active :(

Front 48

SN2 stereochemistry

Back 48

inversion of direction (r-->s) etc
if chiral...

Front 49

it will only lead to an inversion if the ranking of the nucleophile and leaving group are the SAME...

Back 49

if different...no necessarily so!