Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Organic Chemistry > Chapter 7 > Flashcards

Chapter 7 Flashcards

You may prefer our related Brainscape-certified flashcards:
Chemistry 101 flashcards Periodic Table flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

Alkyl Halides:

A

Organic Molecules containing a halogen atom (X) bonded to an sp^3 hybridized carbon atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Alkyl Halides are classified as:

A

-Primary
-Secondary
-Tertiary
This is dependent on the number of carbons bonded to the carbon with the halogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the most important factor in determining the course of an alkyl halides chemical reactions?

A

The classification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the general molecular formula of alkyl halides?

A

Cn H2n+1 X

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where are alkyl halides formally derived from?

A

Replacing a hydrogen atom with a halogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 4 types of organic halides?

A
  • Vinyl Halides
  • Aryl Halides
  • Allylic Halid
  • Benzylic Halide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Vinyl Halides:

A

Have a halogen atom bonded to a carbon-carbon double bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Aryl Halides:

A

Have a halogen atom bonded to a benzene ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which two halides do not undergo the reactions in this chapter?

A

Vinyl and Aryl halides.

These are also attached to an sp2 hybridized C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which halides undergo the reactions in this chapter?

A

Allylic and Benzylic halides

These are also bonded to an sp3 hybridized carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Allylic Halides:

A

Have X bonded to the carbon atom adjacent to a carbon carbon double bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Benzylic Halides:

A

Have X Bonded to the carbon atom adjacent to a benzene ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Fun Fact:

A

Hundreds of organic halides with diverse structures and biological activities have been isolate from red algae of the genus Laurencia, seaweed that grows in shallow water at the edges of reefs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Name properties of alkyl halides:

A
  • weakly polar molecules
  • soluble in organic solvents
  • not water soluble
  • exhibit dipole-dipole interactions
  • As the C chain grows longer, it overshadows the weakly-polar C-X bond, making the molecule less polar
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Alkyl halides undergo nucleophilic substitution reactions. Select all components that are required for a nucleophilic substitution reaction to take place.

A
  • a leaving group
  • a nucleophile
  • an sp3 hybridized C bonded to the leaving group
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the chemical formula for carbon tetrachloride?

A

CCl4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the chemical formula for Chloroform?

A

CHCl3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the chemical formula for dichloromethane?

A

CH2Cl2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the nucleophilic substitution of an alkyl halide:

A
  • a nucleophile donates an electron pair to an electrophilic C atom
  • As the C-X bond is cleaved, the electrons of the C-X sigma bond are accepted by the leaving group
  • The C-X bond is cleaved heterolytically to form radicals
  • The reaction takes place at an sp3 hybridized C atom
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

In any nucleophilic reaction a ________ attacks an ____ hybridized C atom and displaces a ______ group

A

nucleo
sp3
leaving

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

T/F Negatively charged nucleophiles are often used as salts. The identity of the counterion used to balance the charge is often inconsequential, and therefore it is omitted from the chemical equation.

A

True

Reason: Nucleophiles like -SH are often used as salts with Li+, Na+, or K+ counterions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

The following steps are needed to draw the product of any nucleophilic substitution reaction. Place the steps in the correct order with the first step at the top of the list.

A
  1. Find the sp3 hybridized carbon with the leaving group
  2. Identify the nucleophile, the species with a lone pair or pi bond
  3. Substitute the nucleophile for the leaving group and assign charges (if necessary) to any atom involved in bond breaking/formation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

The nucleophile ____ an electron pair

A

donates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The carbon atom at which substitution occurs ____ an electron pair from the nucleophile

A

accepts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

The lewis base in a nucleophilic substitution reaction is the

A

nucleophile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The lewis in a nucleophilic substitution reaction is the _______

A

carbon atom at which substitution occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

All good leaving groups are ____ bases with relatively ____ conjugate acids that have _____ pKa values

A

weaker
strong
low

28
Q

Leaving group ability _____ from left to right across a row of the periodic tables as basicity ______

A

increases

decreases

29
Q

Is Cl- a good leaving group?

A

Yes, it is a weak base

30
Q

Rate I- , H2N-, HO-, and Br- from best to worst leaving group

A

I-
Br-
HO-
H2N-

31
Q

Why is F- a poor leaving group?

A

The C-F bond is very strong

32
Q

Is H2O a good leaving group?

A

Yes because it is a weak base

33
Q

Is HO- a good leaving group?

A

No it is a strong base and a poor leaving group

34
Q

Is I- a good leaving group?

A

Yes it is a weak base

35
Q

What is steric hindrance?

A

A decrease in reactivity resulting from the presence of bulky groups at the site of a reaction

36
Q

Nucleophilicity does not parallel basicity when ____ ______ becomes important

A

Steric Hindrance

37
Q

What is steric strain?

A

An increase in energy when big groups (occupying a large volume) are forced close to each other

38
Q

The steric bulk of the tert-butoxide anion ______ its reactivity as a nucleophile without affecting its ability to act as a base. A sterically hindered based that is a poor nucleophile is called a _________ base

A

decreases;

nonnucleophilic

39
Q

What are comparisons between nucleophiles and bases?

A
  • A nucleophile is a lewis base that attacks electrophiles other than protons
  • Nucleophiles and bases have a lone pair or pi bond
40
Q

It is generally true that a strong base is a ______ nucleophile, although steric factors and solvent effects can alter this relationship

A

strong

41
Q

Are polar protic solvents capable of intermolecular hydrogen ponding? And why?

A

Yes because they contain an O-H or N-H bond.

42
Q

Do polar protic solvents solvate cations are anions?

A

They solvate both well.

43
Q

Cations are solvated by?

A

Ion-dipole interactions

44
Q

Anions are solvated by?

A

Hydrogen bonding

45
Q

Nucleophilicity increases _____ a column of the periodic table

A

down

46
Q

In a polar protic solvent, nucleophilicity _____ down a group of the periodic table as the size of the anion _____ and basicity _____.

A

increases
increases
decreases

47
Q

What are correct characteristics of polar aprotic solvents?

A
  • A polar aprotic solvent solvates cations by ion-dipole interactions.
  • Acetone is a polar aprotic solvent because it cannot act as a hydrogen-bond donor
48
Q

Which solvents are both polar and protic?

A
  • water, H2O
  • acetic acid, CH3COOH
  • ethanol, CH3CH2OH
49
Q

T/F HS- is a more powerful nucleophile than HO-

A

True

50
Q

T/F smaller anions are more strongly solvated than large anions and are less nucleophilic.

A

True

51
Q

T/F Nucleophilicity increases up a column of the periodic table

A

False. Nucleophilicity increases down a column of the periodic table

52
Q

In a polar aprotic solvent such as acetone, the _____ the base the stronger the nucleophile. In this type of solvent, nucleophilicity ______ down a group on the periodic table as basicity ______

A

stronger
decreases
decreases

53
Q

In a polar aprotic solvent such as acetone, Cl– is a _____ nucleophile than Br– but in a polar protic solvent Cl– is the _____ nucleophile of the pair.

A

stronger

weaker

54
Q

SN2 reactions _____.

A
  • are bimolecular reactions

- follow second order kinetics

55
Q

The hydroxide anion –OH is a _____ base than the chloride anion Cl– and therefore in a polar aprotic solvent –OH will be a _____ nucleophile.

A

stronger

stronger

56
Q

What does backside attack allow?

A

The reacting carbon to retain its stereochemistry

57
Q

Select all the statements that describe the mechanism of the SN2 reaction.

A
  • the bond to the nucleophile is formed in the same step as the bond to the leaving group is broken
  • the reaction follows second-order kinetics
  • complete inversion of stereochemistry is observed at the reacting center
58
Q

Sn1 reaction:

A

The rate is doubled when the concentration of the alkyl halide is doubled.

59
Q

sn2 reaction:

A

The rate is quadrupled when the concentration of both the alkyl halide and nucleophile are doubled.

60
Q

Select all the statements that correctly describe the reaction coordinate vs. energy diagram for an SN1 reaction.

A

The energy diagram shows two energy maxima corresponding to the two transition states.

The first step of the reaction is endothermic.

The energy of the first transition state is higher than the energy of the second transition state.

61
Q

As the degree of substitution of an alkyl halide increases, the rate of the SN2 reaction it undergoes will _____. A 1° alkyl halide will therefore have a _____ rate of reaction than a 2° alkyl halide.

A

decrease

faster

62
Q

Describe the structure of a carbocation.

A

The positively charged C atom of a carbocation has an empty p orbital available for bonding.

The positively charged C atom of a carbocation is sp2 hybridized.

63
Q

An SN1 reaction is a _____-step process whose energy diagram contains _____ transition state(s) and _____ reactive intermediate(s).t

A

two
two
one

64
Q

Racemization is the formation of equal amounts of two products that are
_______ of each other from a single chiral starting material

A

enantiomers

65
Q

Which type of alkyl halide is most reactive in an SN1 reaction?

A

Tertiary

66
Q

Correctly describe inductive effects:

A

Inductive effects operate through σ bonds only.

Alkyl groups can stabilize a positive charge by induction.

67
Q

The Hammond postulate does what:

A

The rate of a reaction depends on Ea, and the stability of a product depends on ΔG°.

The Hammond postulate provides an estimate of the energy of the transition state for a reaction.

Organic Chemistry (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions