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Organic Chemistry > Chapter 7 > Flashcards

Chapter 7 Flashcards

1
Q

alkene = olefins meaning?

A

oil forming gas

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2
Q

what is the functional group of an alkene?

A

the carbon carbon double bond

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3
Q

What gives an alkene its reactivity?

A

the carbon carbon double bond

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4
Q

saturated

A

no carbon double bonds

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5
Q

unsaturated

A

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

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6
Q

what are elements of unsaturation

A

pi bonds and rings

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7
Q

Degree of Unsaturation / Index of Hydrogen deficiency equation

A

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

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8
Q

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

A
  • double bond = 1
  • ring = 1
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9
Q

when naming alkenes, how should you number the chain?

A

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)

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10
Q

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

A

between the first and second carbon

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11
Q

how do you name an alkene with multiple double bonds?

A

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

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12
Q

Z = cis or trans?

A

cis

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13
Q

E = cis or trans?

A

trans

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14
Q

when should you use cis/ trans?

A

simple, disubstituted alkenes

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15
Q

when should you use E/Z?

A

tetra and tri substituted alkenes

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16
Q

in cyclic compounds, is cis or trans more stable?

A

cis

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17
Q

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

A

8 carbons

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18
Q

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

A

cis, trans

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19
Q

which has a greater dipole, cis or trans?

A

cis

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20
Q

which has a higher boiling point, cis or trans?

A

cis

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21
Q

define hydrogenation

A

an alkene transforming into an alkane

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22
Q

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

A

MORE

because is is more stable

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23
Q

more substituted = more _____________

A

stable

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24
Q

what causes ring strain in cycloalkenes?

A
  • small ring
  • trans double bond
25
Q

Bredt’s Rule

A

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

26
Q

physical properties of alkenes

A
  • low boiling points (increaded by high molecular weight and suface area)
  • less dense than water
  • nonpolar
27
Q

what increases an alkenes boiling point?

A
  • increased mass
  • decrease branching
28
Q

what is an elimination reaction?

A

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

29
Q

E2 Reaction: strong or weak nucleophile?

A

strong

30
Q

E2 Reaction: unsubstitutued or highly substituted leaving group?

A

highly substituted (want bulky)

31
Q

E2 Reaction: concerted to two-step?

A

concerted

32
Q

E2 Reaction: rate

A
  • bimolecular
  • k[Nu][RX]
33
Q

E2 Reaction: stereochemistry

A

anti-coplanar

34
Q

E2 Reaction: reactivity

A

3>2>1>Me

35
Q

E1 Reaction: strong or weak?

A

weak

36
Q

E1 Reaction: unsubstitutued or highly substituted leaving group?

A

highly substituted

37
Q

E1 Reaction: concerted or two step?

A

two step

38
Q

E1 Reaction: rate

A
  • unimolecular
  • k[RX]
39
Q

E1 Reaction: stereochemistry

A

doesn’t matter

40
Q

Elimination steps

A
  1. leaving group leaves
  2. solvent takes a proton and forms a double bond
41
Q

E1 rate limiting step

A

transition state

42
Q

Zaitsev’s Rule

A

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

43
Q

E2: Hofmann

A

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

44
Q

which is more stable, Zaitsev or Hofmann?

A

Zaitsev

45
Q

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

A

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

46
Q

examples of strong alkyl halides

A

EtO- , -OH , RSH, ZRS

47
Q

examples of weak alkyl halides

A

EtOH, H2O

48
Q

dehydration of alcohols produces what?

A

an alkene and H3O+

49
Q

dehydration of alcohols steps

A
  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
50
Q

which reactions favor a strong base?

A

SN2 or E2

51
Q

which reactions favor a weak base?

A

SN1 or E1

52
Q

which reaction favors primary halides?

A

SN2

53
Q

which reaction favors tertiary halides?

A

SN1, E1, E2 (CANNOT OCCUR IN SN2)

54
Q

which reaction favors heat?

A

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

55
Q

which reaction does bulky bases favor?

A

E1 or E2

56
Q

common bulky bases (makes E2)

A
  • t-buO-
  • LDA
  • LiTMP
57
Q

common bases (makes E2)

A
  • RO-
  • RC (triple bond) C
  • NH2-
  • H-
  • heat
58
Q

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

A

easier (3>2>1)

59
Q

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

A

carbocation (3 and 2 make good carbocations)

Organic Chemistry (9 decks)

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