Hydroxy derivatives
Alcohols
Phenols
Chemical nomenclature

Hydroxy derivatives
basic reactivity of alcohols:
1. formation of alcoholates (salts)
- for removal of proton a stronger base is needed than is basicity of the alcoxide anion
formation of alcoxide
sodium ethoxide
propoxide magnesium chloride

Acidity of alcohols
The lower is pKa , the stronger is the acid
Acidity is influenced by the structure of the alcohol
Alcohols are relatively week acids, less acidic than water
Compare the acidity with other acids and take to considation, that the more acidic is the acid, the
less acidic is its conjugated base
acidity is growing
basicity is growing
Hydroxy derivatives

Hydroxy derivatives
Physical properties of alcohols and comparison with hydrocarbons
Formation of hydrogen bonding (various types)
formation of agregates

Spektral analysis – Infrared spectrum
Spectrum is record of absorbance dependence upon the wavelength of radiation
During measurement of the spectrum the compound is irradiated and interaction with the radiation is
observed. The way the energy interacts with the matter depends upon the wavelength. Relation
between wavelenght and energy is given by Planck equation:
      E is energy
       h    Planck constant
       c    rate of light in vacuum
       n    frequence of radiation
       l     wavelength
  A   is absorbance
  Io,I intensities of light before and after passing the           measured matter
   e   molar extinction coeficient
   c   molar concentration of measured matter
    l    thickness of the meassured layer in cm
   T    transmittance

Dependence of energy upon the wavelenght and possible spectra in shown regions
Energy of infrared wavelenght is small (between 4-40 kJ/mol) and corresponding is also small
interaction of waves with molecules.
After irradiation molecules are exicitated from their basic vibration states to excitated states.
Different energy difference corresponds to various bonds, which shows absorption at different
wavelength.

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n-butanol
t-butanol

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o-kresol
p-kresol
nO-H = 3600 cm-1
nC-O = 1050 -1200 cm-1

Hydroxy derivatives
basic reactivity of alcohols:
2. nucleophilic substitution of hydroxy group
for the substitution acid catalyst is needed
even strong iodide anion is not able to substitute OH group, because strong leaving nucleophile is
pushing the reaction back
The nucleophility of the leaving OH anion was neutralized by acid (leaving water is a weak
nucleophile)
As an acid may serve also Lewis acid:
Al2O3, ZnCl2, BF3 ….

Hydroxy derivatives
basic reactivity of alcohols:
2. nucleophilic substitution of OH group
- OH group can be transferred into an easy leaving group
alkyl(aryl)sulfonate anion is only very weak nucleophile (it is salt of very strong acid) and
therefore
well leaving group

Hydroxy derivatives
For the substitution of hydroxy group for a halogen serve very often halogenides of sulfur and
phosphorus (these at first are forming esters with alcohols and released halogen anion). The ester
group in the form of anion belong to the very good leaving groups and therefore are substituted by
mentioned halogen anion.

Hydroxy derivatives
basic ways of transformation:
3. water elimination
acid catalysed reactions are characteristic for t-alcohols (here they compet with substitution),
secondary and primarily need harsh conditions
they obey Saytzeff rule (thermodynamical olefines are formed)

Hydroxy derivatives
basic ways of transformation:
3. water elimination
acid catalysed dehydratations are characteristic also for the compounds where by elimination can be
create a double bond  in conjugation with already existing double bond
the mechanism of the reaction may be also E1cB
base
regeneration of the base

Hydroxy compounds
OXIDATION OF ALCOHOL
Primary alcohols
oxidation
Aldehydes
oxidation
Carboxylic acids
Secondary alcohols
oxidation
Ketones
Tertiary alcohols
oxidation
they do not oxidace
Oxidation agents:
Na2Cr2O7 / acetic acid / water (cheap oxid.agent),
CrO3/ H2SO4 / water
PCC (pyridinium-chlorchromate) / dichlormethane (very good agent)

Hydroxy compounds
•Dioles
•1,2 – dioles  = glycoles
•    Reactive compound, which under  various conditions can create several types of products:
formation of epoxides
reaction can go also by an opposite direction
oxirane
ethylenoxide
epoxyethane
1,4-dioxane
polyethylenglycole

Hydroxy derivatives
glycoles with t-carbon atoms can undergo in an acidic medium pinacol rearrangement
pinacol
pinacolon
pinacoline
3,3-dimethylbutan-2-on
dehydration of vicinal dioles
acetaldehyde
acrolein (propenal)

Hydroxy derivatives
PHENOLES
           fenol                   ortho-cresol    p-cresol          m-cresol        3-chlorophenol
pyrocatechine (-ol)     resorcine (-cinol) hydrochinone pyrogallole    fluoroglucinol
a-naphtole                                                   b- naphtole

Hydroxy derivatives
PHENOLES
reactivity of phenols:
1.acidity of hydrogen atom
2.ability to react in o- and p- position activated for SEAr
3.ability to react with nucleophile in neigbourhood of oxygen atom is very limited
Phenoles are able to form salts – phenolates even with weak bases and in water
sodium phenolate

Phenol
pKa
phenol
9,88
p-cresol
10,17
o-cresol
10,20
p-methoxyphenol
10,21
p-cyanophenol
7,95
p-chlorophenol
9,20
p-nitrophenol
7,15
2,4-dinitrophenol
3,95
2,4,6-trinitrophenol
0,37
1-naphtol
9,30
2-naphtol
9,55
Hydroxy derivatives
Acidity of phenols
!!! compare acidity with alcohol !!!
        pK a ethanol  15,9
INFLUENCE OF SUBSTITUTION

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o-cresol
p-cresol
nO-H = 3600 cm-1
nC-O = 1050 -1200 cm-1

Hydroxy derivatives
reactivity of phenols:
1. acidity of hydrogen atom
2. ability to react in o- and p- position activated for SEAr
3. ability to react with nucleophile in neigbourhood of oxygen atom is very limited

Hydroxy derivatives
Obr
Donating group is directing entrance of electrophile to ortho- or para-position
Hydroxy group, in comparison with donating methyl group is stronger donor. You can notice –I efect,
but +M efect is prevailing for stabilization s-complex in ortho and para pozition and therefore is
directing to these positions.

Hydroxy derivatives
reactivity of phenols:
1. acidity of hydrogen atom
2. ability to react in o- and p- position activated for SEAr
3. ability to react with nucleophile in neigbourhood of oxygen atom is very limited
the bond between oxygen and carbon atom of aromatic system is reinforced by a mesomeric effect of
oxygen atom – the bond is difficult to split
Proof
the bond between carbon atom of alifatic system undergoes splitting (but no bond between oxygen and
sp2 carbon atom)

Hydroxy derivatives
Oxidation of phenols
metal oxides (PbO2, MnO2, Fe3+), electrochemically
realtively stabil radical is formed
(application as radical scavenger)
very easy proceeds oxidation of dihydroxy compounds
under formation of QUINONES
p-benzoquinone
o-benzoquinone

Hydroxy derivatives
Quinones are important also in biological systems
Their redox properties are playing important role in cells; they are biochemical oxidation agents
(they transfer electrones during energy creation)
ubiquinone (coenzym Q)

Ethers
Nomenclature
alkylalkylether  dimethylether
             diethylether
prefix     alkoxy- (the base for the name is the bigger part of molecule)
ethyl-4-methoxybutanoate
4-bromo-3-butoxybenzaldehyde

Ethery
Ethery jsou těkavé látky: srovnej teplotu varu s teplotou varu alkoholu
diethylether                    b.v. 34oC
ethanol           b.v. 78oC
tetrahydrofuran THF  b.v. 67oC
difenylether    b.v. 259oC
nc-O= 1060 – 1150 cm-1

Ethers
ethers belong to low reactive compounds and therefore are often used as solvents
expected reactivity :
1.interaction of free electron pairs with electrophiles
2.elektron gap at C atom in the neigbourhood of oxygen offers possibility of nucleophilic atack
3.hydrogen atom in b-position may be attacked by a base in elimination reactions