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7/25/2019 Hidrocarbon Alkanes and Reactions
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HIDROCARBON OF ALKANES,ALKENES AND ALKYNES
Organic Chemistry
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Alkane Formulas
All C-C singlebons
Sa!ura!e "i!##$rogens
Ra!io% CnH&n'&Alkane #omologs%
CH()CH&*nCH(Same ra!io +or
bran#e alkanes
Chapter 3 2
CH
H
C
H
H
C
H
H
C
H
H
HH
Butane, C4H10
CH
H
C CH HH
C H
H
H
HH
Isobutane, C4H10
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Common Names
Isobu!ane, isomer o+bu!ane.
Iso/en!ane, iso#e0ane, e!1,me!#$l bran# on ne0!-!o-las!arbon in #ain1
Neo/en!ane, mos! #ig#l$
bran#eFi2e /ossible isomers o+
#e0ane,
34 isomers o+ o!ane an 56Chapter 3 3
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Pentanes
Chapter 3 4
CH
H
C
H
H
C
H
H
C
H
C
HH
H
H
H
n-pentane, C 5H12
CH
H
C CHH
C H
H
H
HH
C
H
H
H
isopentane, C5H12
=>
C
CH3
CH3H3C
CH3
neopentane, C5H12
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I89AC Names
Find the longest continuous carbonchain.
Number the carbons, startingclosest to the frst branch.
Name the groups attached to the
chain, using the carbon number asthe locator.
Alphabetize substituents.
Use di-, tri-, etc., or multiples oChapter 3 5
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Longes! C#ain
The number o carbons in thelongest chain determines the basename: ethane, heane. !"isted in
Table #.$, page %&.'( there are t)o possible chains)ith the same number o carbons,use the chain )ith the most
substituents.
Chapter 3 6
C
CH3
CH2
CH3
CH CH2 CH2 CH3
CH CH2 CH3
H3C
H3C
=>
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Number !#e Carbons
*tart at the end closest to the frstattached group.
( t)o substituents are e+uidistant,loo or the net closest group.
Chapter 3 7
1
2
3 4 5
6 7
CHH3C
CH3
CH
CH2CH3
CH2 CH2 CH
CH3
CH3
=>
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Name Alk$l :rou/s
#-, meth/l
#$-, eth/l
#$$-, n-prop/l
#$$$-, n-but/l
Chapter 3 8
CH3 CH CH2 CH3sec-butyl
CH3 CH
CH3
CH2
isobutyl
CH3 CH CH3
isopropylCH3C
CH3
CH3tert-butyl
=>
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9ro/$l :rou/s
Chapter 3 9
C
H
H
H
C
H
H
C
H
H
H
n-propyl
C
H
H
H
C
H
C
H
H
H
isopropyl
H
A primary carbon A secondary carbon
=>
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Bu!$l :rou/s
Chapter 3 10
C
H
H
H
C
H
C
H
H
C
H
H
H
C
H
H
H
C
H
C
H
HH
C
H
H
n-butyl sec-butyl
H
H
A primary carbon A secondary carbon
=>
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(sobut/l 0roups
Chapter 3 11
CHH
H
C
C
H H
C
H
H
H H
CHH
H
C
C
H H
C H
H
H
H
H
H
A primary carbon A tertiary carbon
=>
isobutyl tert-butyl
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Al/#abe!i;e
Alphabetize substituents b/ name.
(gnore di-, tri-, etc. or
alphabetizing.
Chapter 3 12
CHH3C
CH3
CH
CH2CH3
CH2 CH2 CH
CH3
CH3
3-ethyl-2,6-dimethylheptane
=>
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Com/le0Subs!i!uen!s
( the branch has a branch,number the carbons rom the pointo attachment.
Name the branch o1 the branchusing a locator number.
Parentheses are used around the
comple branch name.
Chapter 3 13
12
3
1-methyl-3-(1,2-dimethylpropyl)cyclohexane
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9#$sial 9ro/er!ies
Solubility: hydrophobic
Density: less than 1 g/m
!oiling points increase "ith
increasing carbons (little less #or
branched chains)$
%elting points increase "ith
increasing carbons (less #or odd-number o# carbons)$
Chapter 3 14
2 ili P i t
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2oiling Points oAlanes
Chapter 3 15
Branched alkane ha!e le "r#ace area c$ntact,
$ %eaker interm$lec"lar #$rce&
=>
3 lti P i t
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3elting Points oAlanes
Chapter 3 16
Branched alkane pack m$re e##iciently int$
a crytalline tr"ct"re, $ ha!e hi'her m&p&
=>
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2ranched Alanes
"o)er b.p. )ith increasedbranching
igher m.p. )ith increasedbranching
4amples:
Chapter 3 17
H
CH3CH
CH3CH2 CH2 CH3
bp 60Cp -154C
CH3CH
CH3CH
CH3
CH3 bp 5!C
p -135C
=>
bp 50Cp -"!C
CH3 C
C 3
CH3
CH2 CH3
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3a5or Uses o Alanes
&-$: gases !natural gas'
#-6: li+uifed petroleum !"P0'
7-%: gasoline8-&9: diesel, erosene, 5et uel
&-up: lubricating oils, heating oil
;rigin: petroleum refning
=>
Chapter 3 18
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Crackin' and hydr$crackin' (ind"trial)
*al$'enati$n
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onormers o Alanes
*tructures resulting rom the reerotation o a - single bond
3a/ di1er in energ/. The lo)est-
energ/ conormer is mostpre=alent.
3olecules constantl/ rotate
through all the possibleconormations.
=> Chapter 3 20
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4thane onormers
*taggered conormer has lo)estenerg/.
>ihedral angle ? 9@ degrees
Chapter 3 21
H
H
H
H
H H
+e%man
pr$ecti$na%h$re
=>
m$del
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/cloalanes
Chapter 3 22
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Naming /cloalanes
Chapter 3 23
/cloalane usuall/ base compoundNumber carbons in ring i &
substituent.First in alphabet gets lo)est
number.
3a/ be c/cloal/l attachment tochain.
CH2CH3
CH2CH3
CH3 =>
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is-Trans (somerism
Chapter 3 24
is: lie groups on same side o ring
Trans: lie groups on opposite sideso ring
?
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/cloalane *tabilit/
Chapter 3 25
7- and 9-membered rings moststable
2ond angle closest to &@8.7
Angle !2ae/er' strain
3easured b/ heats o combustionper -$ -
?
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eats o ombustion AlaneB ;$ ;$ B $;
Chapter 3 26
#on$-%&ain
157'4 157'4
166'6 164'015!'7 15!'6
=>
15!'3
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/clopropane
"arge ring strain due to anglecompression
Cer/ reacti=e, )ea bonds
Chapter 3 27
=>
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/clopropane !$'
Torsional strain because o eclipsedh/drogens
Chapter 3 28
=>
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/clobutane
Angle strain due to compression
Torsional strain partiall/ relie=edb/ ring-pucering
Chapter 3 29
=>
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/clopentane
( planar, angles )ould be &@%, but allh/drogens )ould be eclipsed.
Pucered conormer reduces torsional
strain.
Chapter 3 30
=>
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/cloheane
ombustion data sho)s itDsunstrained.
Angles )ould be &$@, i planar.The chair conormer has &@8.7
bond angles and all h/drogens are
staggered.No angle strain and no torsional
strain.
Chapter 3 31
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hair onormer
Chapter 3 32
=>
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&,#->iaial (nteractions
Chapter 3 33
=>
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>isubstituted/cloheanes
Chapter 3 34
=>
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is-Trans (somers
2onds that are cis, alternate aial-e+uatorial around the ring.
Chapter 3 35
CH3
CH3
=>
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2ul/ 0roups
0roups lie t-but/l cause a largeenerg/ di1erence bet)een the aialand e+uatorial conormer.
3ost stable conormer puts t-but/le+uatorial regardless o othersubstituents.
Chapter 3 36=>
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2ic/clic Alanes
Fused rings share t)o ad5acent carbons.
2ridged rings share t)o nonad5acent
Ds.
Chapter 3 37
bicyclo"3#1#0$he%ane
bicyclo&3$1$'hexane
bicyclo"2#2#1$heptane
=>
bicyclo&2$2$1heptane
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Cis- and Trans->ecalin
Fused c/cloheane chair conormers
2ridgehead Ds cis, structure more
Eeible2ridgehead Ds trans, no ring Eip
possible.
Chapter 3 38
H
H
cis-decalin
H
H
=>
trans-decalin
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nd $# Chapter 3