Upload
ev3rgreen
View
231
Download
0
Embed Size (px)
Citation preview
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 2/24
Functional Class Nomenclature of Alkyl HalidesFunctional Class Nomenclature of Alkyl Halides
Name the alkyl group and the halogen as
separate words (alkyl + halide)
CH3F CH3CH2CH2CH2CH2Cl
3 2 2 2 3 H
I
-
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 3/24
Nomenclature of Alkyl Halides
CH3Cl CH3CH2FCH3CHI CH3CH2CHBr
3chloromethane fluoroethane2-iodopropane 2-bromobutane
CH3 CH3
3 2 2 2 2 3
Br
2-bromo-5-methylheptane
3 2 2 2 2
CH3
1-chloro-5,5-dimethylhexane
I
Br
CH2CH3
Cl
1-ethyl-2-iodocyclopentane CH3
4-bromo-2-chloro-1-methylcyclohexane
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 4/24
Different Kinds of Alkyl Halides
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 5/24
po e momen
a y a ogen es are po ar
HHHH
CC ClCl –
+
HH = 1.9 D
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 6/24
Boiling point increases with increasing
number of halogens
- °
ompounompoun o ng o no ng o n
CH2Cl2 40°C
3
CCl4 77°C
Even though CCl4 is the only compound in this list without a
di ole moment it has the hi hest boilin oint.
Induced dipole-induced dipole forces are greatest in
4 .
Cl is more polarizable than H.
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 7/24
ro uc on o a y a es
RH + X RX + HX
(2) alcohol + hydrogen halide (nucleophilic substitution)
ROH + HX RX + H2O
NaBr
CH3CH2CH2CH2OH CH3CH2CH2CH2Br 2 4
heat
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 8/24
Thion l chloride
SOCl2 + ROH RCl + HCl + SO2
Phosphorous tribromide
r 3 + r + 3 3
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 9/24
em ca proper es
Elimination reactions
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 10/24
uc eop c su s u on reac ons
SN1 reaction: (mostly tertiary halides)reaction rate depends only on the
concentration of the reactant (first order)
reaction rate depends on the concentration of
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 12/24
SN2 reaction:
HO- + CH3 Br Br CH3HO Br
-CH3
+OH
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 13/24
Reaction of Alcohols with Hydrogen
Halides
RROHOH ++ HHXX RRXX ++ HHOHOH
Hydrogen halide reactivity
HHFF HHClCl HHBr Br HHII
eas reac veeas reac ve most reactivemost reactive
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 14/24
ROH + HX RX + HOH
Reactivity of alcohols:
RCH2OH R2CHOH R3COH
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 15/24
An SN2 reaction proceeds in the direction that allows
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 16/24
Elimination reaction
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 19/24
Zajcev's ruleZajcev's rule
in hydrogen halide eliminations hydrogen is
eliminated from the carbon atom which had- HCl CH3 CH CH CH3
originally less hydrogen atomsCH3 CH CH2 CH3
but-2-én2-butene
Cl - HCl CH2 CH CH2 CH3
- -- - -- -
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 20/24
-Aryl halides are halides in which the halogen is
.
-Carbon-halogen bonds in aryl halides are
-
bonds in alkyl halides.
- ecause e car on- a ogen on s s ronger,
aryl halides react more slowly than alkyl halidesw en car on- a ogen on rea ng s ra e
determining (SN only under special conditions).
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 21/24
Ph sical Pro erties of Ar l Halides
resemble alkyl halides
all are essentially insoluble in water less polar than alkyl halides
1.7 D 2.2 D
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 22/24
The most important alkyl halidesThe most important alkyl halides
DichloromethaneDichloromethane CHCH22ClCl22
ChloroformChloroform CHClCHCl33 or anic solventsor anic solvents
CarbontetrachlorideCarbontetrachloride CClCCl44
IodoformIodoform CHICHI antise ticantise tic
TetrafluoroethyleneTetrafluoroethylene CFCF22=CF=CF22 TeflonTeflon®®
22 --
a onsa ons
FreonFreon--1212 CFCF22
ClCl22
fire extinguisher fire extinguisher
HalotaneHalotane CFCF33--CHBrClCHBrCl anestheticsanesthetics
,,
now it is banned, can accumulate over the time (!)now it is banned, can accumulate over the time (!)
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 23/24
Dioxins: ol chloro-dibenzo-dioxins
- formerly pesticide, toxic-
- burning PVC
7/24/2019 32-Organic Halides
http://slidepdf.com/reader/full/32-organic-halides 24/24
Organic halogen compounds:
-Definition of halogen compounds. Functional group and substitutionnomenclature.
- Production of alkyl halides: halogenation of alkanes, reaction of alcohols
and hydrogen halide, thionyl chloride as well as phosphorous tribromide
(with examples).
- Chemical properties of halogen compounds: 2 main types of nucleophilic
substitution. The most frequent substitution reactions of alkyl halides (with
h droxide c anide halide amine h dro ensul hide alcoholate etc.
nucleophiles). Elimination reactions with examples, Zajcev’s rule.
-,
biological importance: ethylchloride, dichloromethane, vinylchloride,
, , , , - , ,
Dioxins, DDT.