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Chapter 10 Flashcards

1
Q

alcohols are important because they can be converted into many other types of compounds, including …, .., …, …, …, and … Not only can alcohols be converted to these compounds, but these compounds can also be converted to alcohols

A

alkenes; haloalkanes; aldehydes; ketones; carboxylic acids; esters

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2
Q

the functional group of an alcohol is an … (…) group bonded to an … hybridized carbon. The oxygen atom of an alcohol is also … hybridized

A

OH; hydroxyl; sp^3; sp^3

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3
Q

the location of the OH group takes precedence over … and … atoms in numbering the parent chain

A

alkyl groups; halogen atoms

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4
Q

common names for alcohols are derived by … bonded to OH and then adding the word …

A

naming the alkyl group; alcohol

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5
Q

we classify alcohols as primary, secondary, tertiary, depending on whether the OH group is on a

A

primary, secondary, or tertiary C

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6
Q

In the IUPAC system, a compound containing two hydroxyl groups is named as a …, one containing three hydroxyl groups as a …, and so on

A

diol; thiol

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7
Q

compounds containing hydroxyl groups on adjacent C are often referred to as

A

glycols

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8
Q

Compounds containing OH and C=C groups are often referred to as … bc of the presence of the C-C double bond.

A

unsaturated alcohols

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9
Q

the parent alkane is numbered to give the … the lowest possible number for alcohols

A

OH

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10
Q

bc of the presence of the polar OH group, alcohols are

A

polar compounds

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11
Q

the attraction between the positive end of one dipole and the negative end of another is called ..

A

dipole-dipole interaction

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12
Q

when the positive end of one of the dipoles is a hydrogen atom bonded to O or N and the negative end of the other dipole is an O or N atom, the attractive interaction between dipoles is particularly strong and is given the special name of

A

H-bonding

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13
Q

An O-H H-bond is considerably … than O-H covalent bond

A

weaker

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14
Q

the alcohols have the higher bps bc more E is needed to overcome the attractive forces of … between their polar OH groups. The presence of additional hydroxyl groups in a molecule further …

A

H-bonding; increases the extent of H-bonding

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15
Q

Bc of increased dispersion forces between larger molecules, bps of all types of compounds, including alcohols, increase with

A

increasing molecular weight

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16
Q

Bc alcohols can interact by H bonding with water, they are more … in water than alkanes and alkenes of comparable molecular weight.

A

soluble

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17
Q

as molecular weight increases, the physical properties of alcohols become more like those of … of … Higher molecular weight alcohols are much less … in water bc of the increase in size of the hydrocarbon portion of their molecules

A

hydrocarbons; comparable molecular weight; soluble;

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18
Q

alcohols can function as both … and …

A

weak acids; weak bases

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19
Q

in dilute aqueous solution, only … is more acidic than water

A

methanol

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20
Q

… has about the same acidity as water. higher-molecular-weight, water-soluble alcohols are … than water

A

ethanol; slightly weaker acids

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21
Q

although alcohols have some acidity, they are not strong enough acids to react with … such as sodium bicarbonate or sodium carbonate

A

weak bases

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22
Q

for simple alcohols like methanol and ethanol, acidity depends primarily on the … and … of the … by water molecules

A

degree of solvation; stabilization; alkoxide ion

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23
Q

as the bulk of the alkyl group bonded to O increases, the ability of water molecules to solvate the alkoxide ion

A

decreases

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24
Q

in the presence of strong acids, the O atom of an alcohol is a … and reacts with an … by … to form an … ion

A

base; acid; proton transfer; oxonium

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25
Q

an important mechanistic theme in many of the rxns of alcohols is that the OH group, a poor leaving group, reacts with protons or a variety of strong electrophiles to create … or analogous group, a much better …, enabling subsequent .. or … rxns to take place

A

OH2+; leaving group; substitution; elimination

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26
Q

Alcohols react with Li, Na, K, and other active metals to liberate … and form … In this oxidation/reduction rxn, Na is oxidized to … and H+ is reduced to …

A

hydrogen; metal alkoxides; Na+; H2

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27
Q

alkoxide ions are nearly the same/somewhat stronger bases than the … ion

A

hydroxide ion

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28
Q

alcohols can also be converted to salts by rxn with bases stronger than …

A

alkoxide ions

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29
Q

rxns of sodium hydride with compounds containing acidic hydrogens are … and …. by the formation of H2, which is given off as a gas

A

irreversible; driven to completion

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30
Q

conversion of an alcohol to a haloalkane involves substitution of … for … at a saturated carbon. the most common reagents for this conversion are the …. (HCl, HBr, and HI) and certain … (PBr3, SOCl2, SOBr2)

A

halogen; OH; halogen acids; inorganic halides

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31
Q

… alcohols react rapidly with HCl, HBr, and HI

A

tertiary

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32
Q

low molecular weight, water soluble primary and secondary alcohols are … when being reacted with HCl at room temp

A

unreactive

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33
Q

primary and secondary alcohols are converted to ….. and … by treatment with hydrobromic and hydroiodic acids

A

bromoalkanes; iodoalkanes

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34
Q

many secondary alcohols give at least some … product, evidence for the formation of … intermediates during their rxn

A

rearranged; carbocation

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35
Q

primary alcohols with extensive beta branching give large amounts of a product derived from

A

rearrangement

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36
Q

based on observations of the relative ease of rxn of alcohols w/ HX and the occurrence of rearrangements, chemists propose an … mechanism for the conversion of tertiary and secondary alcohols to haloalkanes by concentrated HX, with the formation of a carbocation intermediate

A

SN1

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37
Q

(rxn of a tertiary alcohol with HBr-SN1)
1. add a proton: while we often show HBr as the acid present in solution, the actual acid involved in this rxn is … formed by … in aqueous solution . Rapid and reversible proton transfer from H3O+ to the OH group of the alcohol gives an … ion, which converts OH, a poor leaving group, into …, a better leaving group

A

H3O+; dissocation of HBr; oxonium; OH2+

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38
Q

(rxn of a tertiary alcohol with HBr-SN1)

2. break a bond to give stable molecules/ions: loss of … gives a tertiary carbocation intermediate

A

water

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39
Q

(rxn of a tertiary alcohol with HBr-SN1)

3. make a new bond between a nu and an electrophile: rxn of the tertiary carbocat with Br- gives the

A

haloalkane

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40
Q

primary alcohols with no beta branching react with HX by an … mechanism

A

SN2

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41
Q

(rxn of a primary alcohol with HBr-SN2)

  1. add a proton: rapid and reversible proton transfer gives an … ion, which transforms OH, a poor Lv, into …, a better Lv
  2. make a new bond between a nucleophile and an electrophile and simultaneoulsy break a bond to give stable molecules/ions. … of water by Br- gives the bromoalkane
A

nucleophilic displacement

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42
Q

for primary alcohols with extensive beta branching, it is difficult, if not impossible, for rxn to occur by … of H2O from the primary C. Furthermore, formation of a primary carbocation is also difficult, if not impossible. Instead, primary alcohols with extensive beta branching react by a mechanism involving formation of a … intermediate by simultaneous … and … Bc the rate-determining step of this transformation involves only one reactant, namely the protonated alcohol, it is classified as an …r xn

A

direct displacement; tertiary carbocation; loss of water; migration of an alkyl group; SN1

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43
Q

preparation of haloalkanes by treatment of ROH with HX is most useful for … and … alcohols. Bc of the possibility of …, this process is less useful for … alcohols and for … alcohols w/ extensive …

A

primary; tertiary; rearrangement; secondary; primary; branching on the beta C

44
Q

an alternative method for the synthesis of bromoalkanes from primary and secondary alcohols is through the use of …

A

phosphorus tribromide (PBr3)

45
Q

although rearrangement sometimes occurs with PBr3, the extent is considerably less than that with

A

HBr

46
Q

(rxn of a primary alcohol with PBr3)

  1. make a new bond between a nucleophile and an electrophile and simultaneously break a bond to give stable molecules/ions: nucleophilic displacement on phosphorus by the … atom of the alcohol gives a protonated … group, which converts OH into a good Lv
  2. make a new bond between a nu and an electrophile and simultaneoulsy break a bond to give stable molecules/ions: nucleophilic displacement of the protonated dibromophosphite group by bromide ion gives the bromoalkane. The other two bromines on P are replaced in similar rxns, giving … moles of RBr and … moles of phosphorous acid
A

O; dibromophosphite; 3; 1

47
Q

the most widely used reagent for the conversion of primary and secondary alcohols to chloralkanes is … Yields are high and … are seldom observed. the byproducts are HCl and SO2

A

thionyl chloride, SOCl2; rearrangements

48
Q

…. can be used to convert an alcohol to a bromoalkane

A

thionyl bromide, SOBr

49
Q

rxns with SOX2 are most commonly carried out int he presence of … or a …, which … the rxn by forming a small amount of the … in equilibrium. this is more reactive than the alcohol as a nucleophile. In addition, the amine neutralizes the … or … generated during the rxn and prevents unwanted side rxns

A

pyridine; tertiary amide; catalyzes; alkoxide; HCl; HBr

50
Q

a particular value of thionyl halides is that their rxn with alcohols is …; it occurs with …

A

stereoselective; inversion of config

51
Q

a key feature of the rxn of an alcohol with thionyl chloride is the formation of an …, which converts hydroxide into a … that now contains a good Lv. If the rxn betweent he alcohol and thionyl chloride is carried out at 0 degrees C or below, the alkyl chlorosulfite can be isolated

A

alkyl chlorosulfite; chlorosulfite

52
Q

alcohols also rxt with compounds called … to form alkylsulfonates

A

sulfonyl chlorides

53
Q

a sulfonate anion is a very … base and … anion; therefore, it is a very good … in nucleophilic sub rxns

A

weak; stable; leaving group

54
Q

in formation of either a tosylate or a mesylate the rxn involves breaking the … of the alcohol; it does not affect the … bond in any way. If the C bearing the OH group is a chiral center, … formation takes place with … of config

A

O-H; C-O; sulfonate ester; retention

55
Q

a particular advantage of sulfonate esters is that through their use, a hydroxyl group, a very poor leaving group, can be converted to a .. or … group, often shown as OTs and OMs, respectively. Both are very good Lvs readily displaced by nucleophilic substitution

A

tosylate; mesylate

56
Q

an alcohol can be converted to an alkene by

A

dehydration

57
Q

dehydration is most often brought about by … the alcohol with either 85% phosphoric acid or concentrated sulfuric acid. Primary alcohols are the most … to dehydrate and generallly require heating in … at temperatures as high as …
Secondary alcohols undergo acid-catalyzed dehydration at somewhate … Acid-catalyzed dehydration of tertiary alcohols often requires temperatures only slightly …

A

difficult; concentrated sulfuric acid; 180 degrees C; lower temperatures; above room temp

58
Q

when isomeric alkenes are obtained in acid-catalyzed dehydration of an alcohol, the … alkene generally predominates

A

more substituted

59
Q

dehydration of primary and secondary alcohols is often accompanied by

A

rearrangement

60
Q

acid-catalyzed dehydration of secondary and tertiary alcohols involves formation of a … in the rate-determining step and therefore is classified as an … mechanism

A

carbocation; E1

61
Q

(acid-catalyzed dehydr-E1)

  1. add a proton: proton transfer forms OH2, a better Lv
  2. break a bond to give stable molecules/ions: breaking of the … bond and loss of … gives a C+ intermediate
  3. take a proton away: proton transfer from a C adjacent to the … to H2O gives the alkene. In this step, the e- of the C-H sigma bond become the e- of the pi bond
A

C-O; H2O; positively charged C;

62
Q

primary alcohols with liitle/no beta branching undergo acid-catalyzed dehydration to give a … and .. We account for the formation of these products by a combination of … and … mechanisms

A

terminal alkene; rearranged alkenes; E1 and E2

63
Q

As in other cases of acid-catalyzed dehydration of alkenes, the … rule applies, and the more substituted alkene predominates

A

Zaitsev

64
Q

(acid-catalyzed dehydration of an unbranched primary alcohol)

  1. add a proton to give the oxonium ion
  2. take a proton away and simultaneously break a bond to give stable molecules/ions: simultaneous proton transfer to solvent and loss of water gives the C=C of the terminal alkene
  3. 1,2 shift and simultaneously break a bond to give stable molecules/ions : simultaneous shift of a … ion from the beta C to the alpha C and loss of H2O gives a …
  4. take a proton away: transfer of a proton from a C adjacent to the carbocat to … gives the rearranged alkenes
A

hydride; carbocat intemediate; solvent

65
Q

both the alkene hydration and the alcohol dehydration rxns are … and represent … of …

A

reversible; different directions; the same process

66
Q

for the hydration/dehydration equilibrium, large amounts of water favors … formation, whereas scarcity of water or experimental conditions where water is remove favor … formation

A

alcohol; alkene

67
Q

principle of microscopic reversibility: according to this principle, the sequence of transition states and reactive intermediates for any reversible rxn must be …, but in …., for the reverse rxn as for the forward rxn

A

the same; reverse order

68
Q

compounds containing hydroxyl groups on two adjacent C atoms are called … or …

A

vicinal diols; glycols

69
Q

such compounds (glycosl) can be synthesized by a variety of methods, including

A

oxidation by OsO4

70
Q

acid-catalyzed dehydration of glycols involves dehydration to form a … and migration of a … group from one C to an adjacent C. Acid-catalyzed conversion of a pinacol to pinacolone si an example of a type of rxn called the …

A

ketone; methyl; pinacol rearrangement

71
Q

(pinacol rearrangement)

  1. add a proton to form OH2+, a better Lv
  2. break a bond to give stable molecules/ions: loss of water from oxonium gives a carbocat intermediate
  3. 1,2 shift: migration of a methyl group from the adjacent carbon with its bonding e- gives a new, more stable … intermediate. 4. take a proton away: proton transfer to … gives …
A

resonance-stabilized cation; solvent; pinacolone

72
Q

the pinacol rearrangement is … for all glycols

A

general

73
Q

studies of unsymmetrical vicinal diols reveal that the OH group that becomes protonated and leaves is the one that gives rise to the more

A

stable carbocation

74
Q

oxidation of a primary alcohol gives an … or a …, depending on conditions. Secondary alcohols are oxidized to …, Tertiary alcohols …

A

aldehye; carboxylic acid; ketones; are not oxidized

75
Q

one reagent used in the lab for the oxidation of a primary alcohol to a carboxylic acid is …, … A solution of this acid in aqueous sulfiuric acid is known as the … reagent

A

chromic acid; H2CrO4; Jones

76
Q

oxidation by chromic acid is commonly carried out by dissolving organic compounds in acetone and then adding a stoichiometric amount of … to complete it

A

Jones reagent

77
Q

secondary alcohols are oxidized to … by chromic acid

A

ketones

78
Q

tertiary alcohols are resistant to oxidation because the C bearing the OH is already bonded to three C atoms and therefore cannot form an additional … bond. Thus,t he prereq for the oxidation of an alcohol to an aldehyde/ketone is at least one … on the C bearing the OH

A

C-O; H

79
Q

(chromic acid oxidation of an alcohol)
1. rxn of the alcohol and chromic acid gives an … by a mechanism similar to that for the formation of a carboxylic ester.
2. take a proton away and simultaneously break bonds to give stable molecules/ions: rxn of the alkyl chromate with a base results in cleavage of a … bond, formation of the … group, and reduction of chromium (VI) to …
This step is the … step; C undergoes a 2-e- oxidation and Cr undergoes a 2-e- reduction to Cr4, whicht hen participates in further oxidations by a similar mech and eventually is transformed to Cr3

A

alkyl chromate; C-H; carbonyl; chromimum (IV); oxidation-reduction

80
Q

in aqueous chromic acid, a primary alcohol is oxidized first to an … and then to a … In the second step, it is not the aldehyde that is oxidized, but rather the … formed by addition of a molecule of water to the ..An OH of the aldehyde hydrate reacts with chromic acid to complete the oxidation of the aldehyde to a ….

A

aldehyde; carboxylic acid; aldehyde hydrate; aldehyde carbonyl group (hydration); carboxylic acid

81
Q

the hydration step is critical bc it converts the aldehyde carbonyl tnto two … groups. Chromic acid can only react with OH to form an alkyl chromate ester, not a carbony. The hydration process is catalyzed by …, and although equilibrium favors the aldehyde, enough hydrate is made to complete the rxn

A

hydroxyl; acid;

82
Q

the form of Cr(VI) most commonly used for oxidation of a primary alcohol to an aldehyde is prepared by dissolving CrO3 in aqueous HCla nd adding pyridine to precipitate … as a solid. PCC is not only selective for the oxidation of primary alcohols to … but also has little effect on C=C bonds or other easily … functional groups

A

pyridinium chlorochromate (PCC); aldehydes; oxidized

83
Q

PCC does not oxidize aldehydes further bc the reagent is not used in water. without water, the product aldehyde is not in equilibrium with the

A

aldehyde hydrate

84
Q

both PCC and H2CrO4 can be used for the oxidation of a secondary alcohol to a

A

ketone

85
Q

Swern oxidation uses … as the oxidizing agent

A

chlorosulfonium salt

86
Q

with swern, primary alcohols are cleanly oxidized to …, secondary yields …, and tertiary are again … it accomplishes the same transformatiosn as …

A

aldehydes; ketones; unreactive; PCC

87
Q

…. also achieves the same transformations as PCC and Swern

A

Dess-Martin periodinane

88
Q

hypervalent means a compound with a greater electron count than

A

predicted by the octet rule

89
Q

periodic acid … is used for the cleavage of a glycol to two …

A

H5IO6; carbonyl groups

90
Q

HIO4 oxidations are restricted to glycols that can form a … Any glycol that can’t is not oxidized by …

A

five-membered cyclic periodate; periodic acid

91
Q

the functional group of a thiol is an … (…) gorup bonded to a … hybridized C

A

SH; sulfhydryl; sp^3

92
Q

there is considerably more … character in the bonding orbitals of divalent sulfur than there is in those of divalent oxygen

A

p

93
Q

thiols are often referred to as …, which means … They react with … in aqueous solution to give … salts as precipitates

A

mercaptans; mercury capturing; Hg2+; sulfide

94
Q

the location of the SH group takes precedence over … and … in numbering, but … takes precedence over SH

A

alkyl groups; halogens; OH

95
Q

in compounds containing both OH and SH, an SH group is indicated by the prefix …

A

sulfanyl

96
Q

because of the very low polarity of the S-H bond, thiols show little association by … Consequently, they have lower … and are less … in water and other polar solvents than alcohols of comparable molecular weights

A

H-bonding; boiling points; less soluble

97
Q

the most common preparation of thiols, RSH, depends on the high … of the hydrosulfide ion, HS-

A

nucleophilicity

98
Q

rxn of HS- with a haloalkane gives a … the scope and limitations of this rxn are governed by the limitations of the … rxn and by competition between … and … the rxn is most useful for preparation of thiols from … haloalkanes. yields are lower from … halides because of the competing … with tertiary halides … predominates, and the alkene formed by dehydrohalogenation is the major product

A

thiol; SN2; substitution; beta elimination; primary haloalkanes; secondary; beta elimination rxn; E2

99
Q

… is much more acidic than water

A

hydrogen sulfide

100
Q

thiols are stronger acids than

A

alcohols

101
Q

the greater acidity of thiols compared to alcohols can be explained by the fact that sulfur is … than oxygen,, so the negative charge on an RS- ion is … over a larger area and is therefore more … than the negative charge on an alkoxide ion

A

larger; delocalized; stable

102
Q

thiols are sufficiently strong acids so that when dissolved in aqueous sodium hydroxide, they are converted completely to

A

alkylsulfide salts

103
Q

many of the chemical properties of thiols stem from the fact that the sulfur atom of a thiol is … easily to several higher oxidation states

A

oxidized

104
Q

thiols are oxidized to disulfides by

A

molecular oxygen

105
Q

thiols are … nucleophiles and thiolates are … nucleophles. they rank as better nucleophiles in both netural and anionic states as compared to … and …, respectively. the reasion si bc S is more … than O, which enhances nucleophilicity. also because the pKa values for thiols are generally …, the anions react with … primarily through an … mechanism rather than an … the reverse is true for …

A

moderate; good; alcohols; alkoxides; polarizable; less than 11; secondary haloalkanes; SN2; E2

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