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Organic Chemistry I > Chapter 6: ROH > Flashcards

Chapter 6: ROH Flashcards

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1
Q

functional group definition

A

structural unit responsible for characteristics, physical and chemical properties under conditions

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2
Q

what are the 2 different naming conventions in IUPAC

A 
functional class
substitutive
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3
Q

what IUPAC naming class is preffered

A

substitutive

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4
Q

main difference between functional class and substitutive names

A 
functional - alkyl followed by "alcohol"
substitutive - start with longest C chain that has the OH group
number closest to OH
replace -ane with -ol
substituents and location BFORE parent
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5
Q

where is OH assumed to be attached in cyclic alcohols

A

C-1

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6
Q

does alcohol or a halogen have higher priority

A

OH has higher priority than halo

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7
Q

how is the C-O bond made in alcohols

A
  • overlap of sp3 orbital on carbon
  • overlaps with one sp3 on oxygen
  • oxygen is left with 2 nonbonding e- pairs
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8
Q

how are bonds made in alkyl halides

A

-halogen is connected to the carbon with a SIGMA bond

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9
Q

carbon-halogen bond distances trend

A

C-F < C-Cl < C-Br < C-I

more electronegetive halogen = smaller bond distance

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10
Q

what type of bonds do alkyl halides and alcohols have

A

polar bonds, and may be polar molecules

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11
Q

dipole-dipole attractive forces

A

molecules with permanent dipoles have a stronger dipole-dipole intermolecular interaction than alkanes

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12
Q

why does flouroethane, for example, have a higher boiling point than propane

A

because its dipole-dipole forces are stronger (flourine is very electronegative) and therefore boiling point is higher

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13
Q

what is different about ethanol and its boiling point

A

ethanols boiling point is so high that dipole-dipole interactions are not enough to explain it

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14
Q

explain bonding in alcohols

A

alcohols have hydrogen bonding (dipole-dipole)

partially positive proton of one -OH group interacts with the partially negative oxygen of a second ethanol

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15
Q

hydrogen bond acceptor and donor in alcohol bonding

A

oxygen = hydrogen bond acceptor

OH hydrogen = hydrogen bond donor

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16
Q

what are the onlu elements involved in hydrogen bonding in organic compounds

A

oxygen
nitrogen

NO

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17
Q

what are alcohols and their hydrogen bonds strong enough to do

A

impose structural order

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18
Q

methyl

A

CH3

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19
Q

ethyl

A

CH3CH2

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20
Q

propyl

A

CH3CH2CH2

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21
Q

pentyl

A

CH3(CH2)3CH2

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22
Q

hexyl

A

CH3(CH2)4CH2

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23
Q

iodine and polarization

A

iodine is highly polarizable

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24
Q

why is iodine highly polarizable

A

because the valence electrons are far from the nucleus

induced dipole-induced dipole forces

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25
Q

connection between halogens, dipoles and boiling point

A
  • increase the number of halogens (Cl, Br, I)
  • increases the dipoles
  • increases boiling point
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26
Q

flourine and polarization

A

flourine has very low polarizability, and boiling points do not increase as you increase the amount of flourine

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27
Q

solubility of alkyl halides

A

insoluble in water

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28
Q

solubility of alcohols in water

A

is directly related to the size of the alkyl group that the OH is attached to (the more, the less soluble)

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29
Q

alcohols that are totally miscible in water

A

methyl, ethyl, n-propyl, and isopropyl

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30
Q

what is the only amount of octanol that dissolves in water

A

1 mL 1-octonol in 2000 mL water

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31
Q

densities compared to water

A

less dense than h2O = alkyl flourides and chlorides

more dense than water = alkyl bromides and iodides, CH2Cl2

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32
Q

halogenation and density

A

increasing halogenation increases density

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33
Q

what are the 3 main steps in radical mechanisms

A
  1. chain initiation
  2. chain propagation
  3. chain termination
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34
Q

what type of arrow do you use in radical mechanisms

A

fish-hook arrows

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35
Q

what are the problems associated with halogenation of alkanes

A
  1. different hydrogens can lead to different products

2. can get over-halogenation

36
Q

radical stability

A

methyl < primary < secondary < tertiary

37
Q

synthesis

A

methods of preparation of alkyl halides

38
Q

mechanism

A

the step-by-step description of how reactions take place

39
Q

alcohol reaction rate

A

tertiary alcohols react fastest at low temps

primary alcohols react slowest and need the highest temps

40
Q

bimolecular reaction

A

both reactants change

41
Q

how is the central carbon hybridized in carbocation

A

sp2

positive charge is in the empty p-orbital

42
Q

characteristic of carbocations

A

they are electrophilic

meaning they seek electrons and love them

mean they are lewis acids

43
Q

SN1 nucleophile

A

is a nonbonding electron pair in a p-orbital that interacts with the empty p-orbital of the carbonation to form a sigma bond

44
Q

in Sn1, what must the sum of each individual step equal

A

the overall reaction equation

45
Q

what type of reaction is Sn1 and why

A

substituation reaction

nucleophile chloride takes the place of OH

46
Q

what is important about the slow step in Sn1 step 2

A

unimolecular

rate determining step

the overall reaction cannot go faster than this step

47
Q

where are the alkyl groups attached to stabilize a carbocation

A

directly attached to the positively charges carbon

48
Q

how are carbocations defined

A

methyl, primary, secondary, tertiary depending on how many carbons are directly attached to the cationic carbon

49
Q

stability vs. carbocation type

A

more stable as it is attached to more carbons

least stable is methyl, most is tertiary

50
Q

inductive effect

A

alkyl groups push electron density onto C+

51
Q

how is the methyl cation in inductive effect

A

has an intense positive charge

52
Q

the more the charge is delocalized on a cation…

A

the more stable the cation

53
Q

how are carbocations stabilized

A

by delocalization of electrons from the sigma bonds, to the + carbon in the empty p orbital

54
Q

what does MO theory predict about bonding orbitals

A

predicts a bonding orbital with 2 electrons that spans the sigma bond and the positive carbon

55
Q

relationship between formation of carbocation and stability

A

the rate of formation of the carbocation is related to the stability of the carbocation formed

56
Q

what tracks the stability of the carbocation and why

A

the transition state is closer in energy to the carbocation

so the activation energy tracks the stability of the carbocation

57
Q

what type of reaction is Sn2?

A

a substitution reaction

58
Q

what is an alkeal

A

a protonated alcohol

59
Q

why do primary methyls need SN2

A

because primary methyl carbocations are very unstable, must react in a different way

60
Q

what is thionyl chloride used for in reactions with alcohol

A

to transform primary and secondary alcohols into alkyl chlorides (not tertiary)

61
Q

what is pyridine used for

A

it is a base used to neutralize the acid (HCl) formed

62
Q

phosphorus tribromide reacts with what to form what

A

reacts with alcohols to form alkyl bromides

SN2

63
Q

halogenation of F2

A

is explosive

64
Q

halogenation of I2

A

is endothermic

65
Q

halogenation of alkanes and what they are useful for

A

the reaction is exothermic

useful for Cl2 and Br2

66
Q

what are the intermediates in chlorination of methane

A

free radicals

67
Q

what do free radicals contain

A

unpaired electrons

68
Q

how do yyou classify radicals

A

by how many carbons they are directly attached to

primary, secondary, tertiary and methyl

69
Q

hybridization of carbon atom with unpaired electron

where is the unpaired electron

A

sp2

unpaired electron is in the 2p orbital

70
Q

what makes free radicals more stable and why

A

the more alkyl groups connected to the radical, the substituated and the more stable!

71
Q

trend in stability for free radicals

A

methyl

72
Q

how are radicals produced

A

bond cleavage

73
Q

how many bonding electrons does each atom have in homolytic bond cleavage

A

each atom retains one of the bonding electrons

74
Q

what is bond dissociation enthalpy

A

the energy required for bond to dissociate

75
Q

what happens to bonding electrons in heterolytic cleavage

A

the more electronegative element retains both bonding electrons

76
Q

how can we quantify radical stability

A

comparing the energy required for homolytic bond cleavage

77
Q

relationship between stability of radicals and their bond dissociation enthalpies

A

the less energy, the more stable the radical

78
Q

how are mono halogenation reactions of higher alkanes initiated in lab

A

you use light (hv)

79
Q

what does cyclobutane yield in monohalogenation of higher alkanes and why

A

a single monochlorination product because the 8 hydrogens result in the same product being formed

80
Q

relationship between transition state and abstraction of a secondary hydrogen (compared to primary)

A

the transition state is lower in energy for abstraction of a secondary carbon because a secondary radical is more stable

81
Q

what type of hydrogen does bromination favor

A

tertiary substitution

82
Q

what type of energy pattern is hydrogen atom abstraction for chlorination

A

exothermic

83
Q

what type of energy pattern is hydrogen atom abstraction for bromination

A

endothermic

84
Q

is hydrogen atom abstraction for chlorination or bromination more selective and why

A

bromination because it is endothermic

85
Q

definition of hydrogen abstraction

A

removal of an atom or group from a molecule by a RADICAL

Organic Chemistry I (9 decks)

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