Hidrocarbon Alkanes and Reactions

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

Hidrocarbon Alkanes and Reactions

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