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Organic Chem Is Killing Me > Hydroxy Compounds > Flashcards

Hydroxy Compounds Flashcards

1
Q

[Hydroxy compounds] aliphatic vs aromative/ alocohol vs phenol

A

Alcohol is aliphatic
-OH to sp3 hybridised C

Phenol is aromatic
sp2 hybridised C in benzene ring

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2
Q

[Hydroxy compounds] Physical properties of Alcohol

  • boiling/melting points
  • Solubility in polar/non-polar solvents
  • Type of molecular attraction
A

bp higher than alkanes of similar Mr
soluble in H2O and organic
Solubility decrease when C increase
idid, H-bonds

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3
Q

[Hydroxy compounds] Bp of alcohols

A

Alcohol > alkane (for comparable Mr)
more energy to over stronger H bonds between alcohol molecules than weaker idid between alkane

  1. Length of alkyl chain
    increase size, increase e, more polarisable e cloud
  2. Branching
    more branching, more spherical, less SA, less extensive idid
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4
Q

[Hydroxy compounds] Solubility of alcohol in H2O

A

alcohol > alkanes
more soluble in H2O
-OH present, form H bond

Decrease solubility when C increase
miscible with organic solvents

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5
Q

[Hydroxy compounds] Solubility of alcohols in organic (non polar) and polar solvents

A

Soluble in both due to
polar -OH
non polar hydrocarbon chain

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6
Q

[Hydroxy compounds] alkene to alcohol

A

Electrophilic addition

  1. LABORATORY
    conc H2SO4, cold
    H2O, heat
  2. INDUSTRIAL
    conc H3PO4 catalyst
    Steam
    heat
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7
Q

[Hydroxy compounds] Halogenoalkane to alcohols

A

Nucleophilic substitution
Aqueous NaOH/KOH
heat

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8
Q

[Hydroxy compounds] Aldehyde/Ketone to alcohol

A

Aldehyde (-CHO) to pri 1 alcohol
Ketone (-CO) to sec 2 alcohol

3 possible reagents

  1. LiAlH4 in dry ether, rt
  2. NaBH4 in ethanol, rt
  3. H2, Ni/Pd/Pt catalyst, rt
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9
Q

[Hydroxy compounds] Carboxylic acid to alcohol

A

Reduction
LiAlH4 in dry ether, rt

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10
Q

[Hydroxy compounds] Sites of reactivity

A

3 sites of reactivity

  1. electron deficient C
    partial pos
    susceptible to nucleophilic attack
    R-OH as electrophile
  2. high electron density O partial neg
    R-OH as nucleophile
  3. O-H polarised bond
    RO-H as B-L acid
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11
Q

[Hydroxy compounds] Combustion of alcohol

A

Pale blue flame
CO2 and H2O

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12
Q

[Hydroxy compounds] Alcohol to alkene

A

Dehydration/ Elimination reaction
excess conc H2SO4, heat
or Al2O3 catalst, heat
or conc H3PO4 catalyst, heat

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13
Q

[Hydroxy compounds] Alcohol to halogenoalkane R-X

A

nucleophilic sub
UNCONFIRMED LIST VERY MESSY WILL UPDATE BUT

conc HCl, ZnCl2 catalyst, heat
R-X and H2O

anyhydrous PX3, heat
R-X and H3PO3

anhydrous PCl5 rt
R-Cl abd POCl3 and HCl (g)
can sep products

anhydrous SOCl2, heat
R-Cl and SO2(g) and HCl(g)
cannot separate

Observation:
White fumes of HCl for PCl5 and SOCl2

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14
Q

[Hydroxy compounds] Oxidation of pri vs sec vs tert alochols

A
  • *PRI:** aldehyde(-CHO)/carbo acid(-COOH) +H2O
  • *SEC:** ketone (-CO) +H2O
  • *TERT:** resistant to [O], absence of alpha H
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15
Q

[Hydroxy compounds] Secondary alcohol to ketone

A

Oxidation
Acidified KMnO4/K2Cr2O7, heat
Observations: purple to c-less/orange to green

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16
Q

[Hydroxy compounds] Primary alcohol to aldehyde/carbo acid

A

Oxidation
1. CARBO ACID AS PRODUCT
Acidified KMnO4/K2Cr2O7, heat
Observations: purple to c-less/orange to green

  1. ALDEHYDE AS PRODUCT
    Acidified K2Cr2O7, immediate distil
    KMnO4 is too strong
    Observation: orange to green
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17
Q

[Hydroxy compounds] Test for alcohol

A

Iodoform
Brown I2 decolourise, pale yellow ppt CHI3 formed
eqn 6 4 1 5 5

18
Q

[Hydroxy compounds] Step down reaction of alcohol

A

Iodoform
Brown I2 decolourise, pale yellow ppt CHI3 formed
eqn 6 4 1 5 5

19
Q

[Hydroxy compounds] alcohol to ester

A

Nucleophilic acyl sub
Add -COOH and conc H2SO4 catalyst, heat under reflux
product ester and H2O

or add acyl chloride at rt
product ester and HCl
Preferred becauase milder conditions, go to completion, HCl gas can be removed

20
Q

[Hydroxy compounds] reaction mechanisms involved in nucleophilic acyl sub (alcohol + ? → ester)

A

Addition of nucleophile (alcohol)
Elimination of H and the other one

21
Q

[Hydroxy compounds] Physical properties of phenol

  • boiling/melting points
  • Solubility in polar/non-polar solvents
  • Type of molecular attraction
A

bp/mp phenol>alkane
bp depends on extent of intramolecular H bond
promity of groups like NO2 or OH

sparingly soluble in H2O
weakly acidic

22
Q

[Hydroxy compounds] Structure of phenols

A

Oxygen has 2 lone pair e
O has one sp2 hybridised
the other unhybridised 2p orbital side on overlap with pi e cloud of benzene
and delocalised in bezene ring

23
Q

[Hydroxy compounds] Delocalisation on 2p unhybridised lone pair of e affects

A

reactivity of -OH
reactivity of benzene ring

24
Q

[Hydroxy compounds] Sites of reactivity for phenols

A

OH group:
1. Delocalised lone pair e on O
weak nucleophile
2. Polarised O-H bond
dispersal of neg charge
stabilised conjugate base

Benzene ring:
1. delocalised lone pair into benzene ring
partial double bond character
poor electrophile
2. delocalied lone pair into ring
activated electrophilic sub
benzene ring as nucleophile

25
Q

[Hydroxy compounds] Combustion of phenol

A

very smokey orange flame
combustion is hardly complete
need very high O;phenol proportion

26
Q

[Hydroxy compounds] Phenol to ester

A

Add acyl chloride, phenol in NaOH
rt
get ester and HCl
very slow

UNLIKE NORMAL ALCOHOL
carbo acid and phenol will not react

27
Q

[Hydroxy compounds] for nucleophilic acyl sub to convert phenol to ester why must the phenol be in NaOH

A

Phenol and NaOH gives acid base reaction
convert phenol to phenoxide (neg charge)
stronger nucleophile

28
Q

[Hydroxy compounds] why do phenols not undergo nucleo sub like alchols

A

unhybridised 2p orbital
lone pair e
side on overlap with pi e cloud
lone pair e delocalised into benzene ring
partial double bond character
strengthening CO bond

benzene ring also repels nucleophile because electron rich

29
Q

[Hydroxy compounds] Why can phenols undergo electrophilic sub

A

can electro sub but milder conditions than benzene/methylbenzene

2p orbital unhybridised in O
lone pair of e
side on overlap with pi e cloud
delocalised into ring
benzene ring more e rich
more susceptible to electrophilic sub

30
Q

[Hydroxy compounds] Positions of addition/sub in phenol

A

2,4-directing because strongly ring activating
2,4,6

31
Q

[Hydroxy compounds] Acidity factors

A

relative stability of conjugate base

H-A ⇌ H+ + A-
more stable conjugate base A-
equilibrium pos right
more H+ because greater dissociation
stronger acid HA

e donating groups intensify neg charge
destabilise conjugate base

e withdrawing groups disperse neg charge
stabilise conjugate base

32
Q

[Hydroxy compounds] Ranking acidity of H20 Ethanol and Phenol

A

Ethanol < H2O < Phenol

ethanol
CH3CH2 intensifies neg charge
destabilises ethoxide ion relative to hydroxide

phenol
2p unhybridised lone pair e
side on overlap with pi e cloud
delocalised into ring
disperse neg charge
stabilise phenoxide ion
resonance stabilised

33
Q

[Hydroxy compounds] Alcohols and phenols with metals (Na)

A

Form alkoxide/phenoxide and half mole of H2
cleavage of O-H bonds
Redox
less vigourous reaction than water because alcohols are weaker acids

34
Q

[Hydroxy compounds] Alcohols and phenols with bases (NaOH)

A

Form alkoxide/phenoxide and half mole of H2
only phenols and carbo acid
alcohols are weaker acids
cannot undergo a-b reaction

35
Q

[Hydroxy compounds] Alcohols and phenols with Carbonate (CO3 2-)

A

acid-carbonate reaction
alcohols no reaction
phenols and carbo acid can technically react
but only carbo will go to completion (CO2 produced)
phenol not acidic enough

GOOD TEST FOR COOH because CO2 produced

36
Q

[Hydroxy compounds] test for hydroxy compunds (all including phenols and carbo)

A

add Na
H2 gas should extinguish lighted splint with a pop sound

37
Q

[Hydroxy compounds] test for carboxyl COOH group

A

Add sodium carbonate
CO2 effervescence
white ppt in limewater

38
Q

[Hydroxy compounds] Test to identify aliphatic alochols

A
  1. Nu sub
  2. Acid metal reaction
  3. oxidation
  4. iodoform
39
Q

[Hydroxy compounds] identify aliphatic alcohol using nu sub

A

anhydrous PCl5, rt
OR anhydrous SOCl2, heat
HCl white fumes

40
Q

[Hydroxy compounds] Identify aliphatic alcohol by oxidation

A

only works for pri and sec alcohol
because tertiary has lack of alpha carbon

Add acidified (H2SO4) KMnO4/K2Cr2O7
positive: purple→colourless/orange→green
neg/tertiary: remain purple/orange
41
Q

[Hydroxy compounds] Iodoform test

A

only for the C H OH CH3 group
NaOH and I2 (aq), heat
decolourise brown I2
pale yellow ppt CHI3

42
Q

[Hydroxy compounds] Test for phenol FeCl3

A

Add neutral FeCl3 (aq) at rt
violet colour for positive test from complex ion

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