Chapter 7

Question 1

alkene = olefins meaning?

Answer 1

oil forming gas

Question 2

what is the functional group of an alkene?

Answer 2

the carbon carbon double bond

Question 3

What gives an alkene its reactivity?

Answer 3

the carbon carbon double bond

Question 4

saturated

Answer 4

no carbon double bonds

Question 5

unsaturated

Answer 5

carbon double bond, decreases the number of hydrogens in the molecule by 2

Question 6

what are elements of unsaturation

Answer 6

pi bonds and rings

Question 7

Degree of Unsaturation / Index of Hydrogen deficiency equation

Answer 7

2C+2+N-H-X / 2

Question 8

how much is a double bond and ring in a DoU?

Answer 8

• double bond = 1
• ring = 1

Question 9

when naming alkenes, how should you number the chain?

Answer 9

so that the double bond has the lowest possible number, then signify where the double bond is
(ex: either 2-pentene or pent-2-ene)

Question 10

in a ring, where is the double bond assumed to be by its naming?

Answer 10

between the first and second carbon

Question 11

how do you name an alkene with multiple double bonds?

Answer 11

use di-, tri-, and tetra- before the ending of -ene

Question 12

Z = cis or trans?

Answer 12

cis

Question 13

E = cis or trans?

Answer 13

trans

Question 14

when should you use cis/ trans?

Answer 14

simple, disubstituted alkenes

Question 15

when should you use E/Z?

Answer 15

tetra and tri substituted alkenes

Question 16

in cyclic compounds, is cis or trans more stable?

Answer 16

cis

Question 17

how many carbons does a ring need to have in order for trans to be stable?

Answer 17

8 carbons

Question 18

all cycloalkenes are assumed to be _________ unless otherwise specifically named _________

Answer 18

cis, trans

Question 19

which has a greater dipole, cis or trans?

Answer 19

cis

Question 20

which has a higher boiling point, cis or trans?

Answer 20

cis

Question 21

define hydrogenation

Answer 21

an alkene transforming into an alkane

Question 22

the _______ substituted the double bond, the lower its heat of hydrogenation

Answer 22

MORE

because is is more stable

Question 23

more substituted = more _____________

Answer 23

stable

Question 24

what causes ring strain in cycloalkenes?

Answer 24

• small ring
• trans double bond

Question 25

Bredt's Rule

Answer 25

bridged, bicyclic compound cannot have a double bond at a bridgehead position UNLESS one of the rings contains at least 8 carbon atoms

Question 26

physical properties of alkenes

Answer 26

- low boiling points (increaded by high molecular weight and suface area) - less dense than water - nonpolar

Question 27

what increases an alkenes boiling point?

Answer 27

- increased mass - decrease branching

Question 28

what is an elimination reaction?

Answer 28

they produce double bonded structures and a leaving group (that is often a halide)

Question 29

E2 Reaction: strong or weak nucleophile?

Answer 29

strong

Question 30

E2 Reaction: unsubstitutued or highly substituted leaving group?

Answer 30

highly substituted (want bulky)

Question 31

E2 Reaction: concerted to two-step?

Answer 31

concerted

Question 32

E2 Reaction: rate

Answer 32

- bimolecular - k[Nu][RX]

Question 33

E2 Reaction: stereochemistry

Answer 33

anti-coplanar

Question 34

E2 Reaction: reactivity

Answer 34

3>2>1>Me

Question 35

E1 Reaction: strong or weak?

Answer 35

weak

Question 36

E1 Reaction: unsubstitutued or highly substituted leaving group?

Answer 36

highly substituted

Question 37

E1 Reaction: concerted or two step?

Answer 37

two step

Question 38

E1 Reaction: rate

Answer 38

- unimolecular - k[RX]

Question 39

E1 Reaction: stereochemistry

Answer 39

doesn't matter

Question 40

Elimination steps

Answer 40

1. leaving group leaves 2. solvent takes a proton and forms a double bond

Question 41

E1 rate limiting step

Answer 41

transition state

Question 42

Zaitsev's Rule

Answer 42

if more than one elimination product possible, the most substituted alkene is the major product

Question 43

E2: Hofmann

Answer 43

Hofmann reaction bulky bases cannot form the most stable because they cannot fit in the smaller spots, this will lead to a less stable product

Question 44

which is more stable, Zaitsev or Hofmann?

Answer 44

Zaitsev

Question 45

what does the stereochemistry need to be in order for an elimination reaction to occur?

Answer 45

LG and H need to be 180 degrees from each other (anti-coplanar) --> find the beta hydrogens

Question 46

examples of strong alkyl halides

Answer 46

EtO- , -OH , RSH, ZRS

Question 47

examples of weak alkyl halides

Answer 47

EtOH, H2O

Question 48

dehydration of alcohols produces what?

Answer 48

an alkene and H3O+

Question 49

dehydration of alcohols steps

Answer 49

1. O will take an H 2. H2O will leave and a positive will be created 3. a H will be removed to form a double bond

Question 50

which reactions favor a strong base?

Answer 50

SN2 or E2

Question 51

which reactions favor a weak base?

Answer 51

SN1 or E1

Question 52

which reaction favors primary halides?

Answer 52

SN2

Question 53

which reaction favors tertiary halides?

Answer 53

SN1, E1, E2 (CANNOT OCCUR IN SN2)

Question 54

which reaction favors heat?

Answer 54

E1 or E2 (unless it is primary, then SN2)

Question 55

which reaction does bulky bases favor?

Answer 55

E1 or E2

Question 56

common bulky bases (makes E2)

Answer 56

- t-buO- - LDA - LiTMP

Question 57

common bases (makes E2)

Answer 57

- RO- - RC (triple bond) C - NH2- - H- - heat

Question 58

the more R groups on the alcohol, the ______ to dehydrate

Answer 58

easier (3>2>1)

Question 59

the specific elimination mechanism depends on how easily the molecule will form a ______________

Answer 59

carbocation (3 and 2 make good carbocations)