Mechanism

1
Mechanism
2
Oxidative cleavage
3
Ozonolysis
4
Synthesis of alkynes
5
Synthesis of alkynes
Prepare the alkene (large variety of preparation
methods enables a variety of molecular
architectures) Destroy the double bond by
adding Br2 thus generating a vic-dibromide Doubl
e elimination reaction performed with NaNH2
generates the alkyne No stereochemical
implications gem-dihalides may be used as well
6
The acidity of terminal alkynes
sp2
sp
sp3
pKa 25
44 50
More s character, more stable anion, weaker
conjugated base, better acid
Acidity CH3CH3 lt CH2CH2
lt HCCH Basicity CH3CH2 gt
CH2CH gt HCC
OH lt OR lt CCR lt NH2 lt CHCH2 lt CH2-CH3
7
Alkynides as Good Nucleophiles for
SN2 Good Base for E2
8
Alkynes on the same line as alkenes
Addition of Br2 and Cl2 Addition of
HX Oxidative cleavage
9
Hydrogenation of alkynes
Syn addition for the formation of cis-alkenes
Anti addition for the formation of trans-alkenes
10
Anti addition the mechanism
11
Chemistry of Alcohols and ethers Chapter 11
12
Nomenclature
Just add the suffix ol. All the other IUPAC
rules still apply CH3OH CH3CH2OH
CH3CH(OH)CH3 CH3C(CH)3(OH)CH3 Methan
ol Ethanol 2-propanol
2-methyl-2-propanol
(Isopropanol)
(t-butanol) 10 alcohol 10
20
30
Common names
Phenol benzyl alcohol
2-propenol 2 propynol
13
Examples Give the IUPAC names to the following
2,4-dimethyl-1-pentanol
4-phenyl-2-pentanol
4-pentene-2-ol
14
Ethers Nomenclature
R-O-R dialkyl ether CH3OCH2CH3
CH3CH2OCH2CH3
C6H5OC(CH3)3 Ethyl methyl ether
diethyl ether t-butyl phenyl
ether
Just for complex and polyfunctional
ethers CH3CHCH2CH2CH3

CH3OCH2CH2OCH3
OCH3
2-methoxypentane 1-ethoxy-4-methylbenze
ne 1,2-dimethoxyethane
15
Physical properties
Alcohols much higher BP and MP with
respect to the corresponding
hydrocarbons (hydrogen bridges are very
strong) Ether very comparable to
the corresponding hydrocarbon
(Et2O bp. similar to pentane)
16
Synthesis of alcohols
1. acid-catalyzed hydration of alkenes
(follows Markovnikovs rule)
Markovnikov rule the bulkier group goes on the
most crowded C atom