wade powerpoint/lecture for chapter 1

7/21/2019 Wade Powerpoint/Lecture for Chapter 1

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Chapter 1Introduction and

Review

Organic Chemistry , 8th Edition

L. G. Wade, Jr.



Organic Chemistry Definition:

• Old: “derived from living organisms”

• New: “ chemistry of caron

compounds”

• !riedrich "#hler$s 1%&%

synthesis of urea signaledthe end of “vitalism'” heat

NH4

+ OCN

- H2 N C NH2

O

urea



Organic Chemistry

"hy do we distinguish etween

inorganic and organic compounds(

"hy are organic compoundsimportant(



)tomic *tructure• )toms: protons+ neutrons+ and electrons'

• ,he numer of protons determines theidentity of the element'

• *ome atoms of the same element have adifferent numer of neutrons' ,hese arecalled isotopes'

• -.ample: 1& C+ 1/C+ and 10C



-lectron roperties

• -lectrons have wave properties'

• In the 12&3s+ 4uantum 5echanics wasestalished as a theory to e.plain the wave

properties of electrons'• ,he solution to wave e6uations for electrons

provides us with visual pictures called oritals'

• Oritals are grouped into “ shells+” at differentdistances from the nucleus'



• ,he type or orital e identified y its shape

• )n orital is a region where there is a calculated237 proaility of finding an electron' ,heremaining 137 proaility tapers off as youmove away from the nucleus

-lectron roperties



!irst -lectron *hell

,he 1s orital holds two electrons'



*econd -lectron *hell

2s orbital (spherical)

,hree p oritals

2 p orbital



-lectron Configurations

• )ufau principle: laceelectrons inlowest energy

orital first'• 8und$s rule:

-6ual energyoritals are half9

filled+ then filled'

• C: 1s& &s& &p&

↑↓

↑↓

↑ ↑



-lectron Configurations



;ond !ormation

• Ionic onding: electrons aretransferred'

• Covalent onding: electron pair isshared'



<ewis Dot *tructures

• ;onding electrons

• Nononding electrons or lone pairs

Satisfy the octet rule!

C

H

H

H

OH

onding electrons

nononding electrons



='N' <ewis“the most rilliant scientist to never

win a Noel ri>e”



Lewis’s1902lecture

notesshowing hisidea of

“cubicalatoms” –which later

became



*imple <ewis *tructures

• !or simple <ewis *tructures?1' Draw the individual atoms using dots to

represent the valence electrons'

&' ut the atoms together so they share )IR*of electrons to ma@e complete octets' "8),is an octet(

• ,a@e N8 / + for e.ample?



ro' 19&' Draw <ewisstructures for

f' dimethyl ether

g' fluoroethane

h' oron trifluoride



Representing 5ultiple ;onds



*ome 5ore 5ultiple ;ond<ewis *tructures



ro' 19/' Draw <ewis structures forthe following molecular formulas'

e' 8 & CN8

h' 8NN8



Aalence

• ,he numer of onds an atomusually forms'

C N O H F :

:

: :

:

:



-lectronegativity

•,he aility of an atom toattract electrons to itself ina chemical ond'•One of the most important

concepts in OrganicChemistry ecause?



electronegatiit!

bond "olarit!

molecular sha"efrom #$%&R

molecular di"ole moment

intermolecular attractie forces

&'($)*+L &RO&%R,)%$ O- OL%*

ector addition



Chapter 1

Dipole 5oment • )mount of electrical charge . ond length'

• Charge separation shown y electrostatic potential map B-5'

• Red indicates a partially negative region and lue indicates a partially positive region'



Chapter 1

-lectronegativity and;ond olarity

=reater electronegativity differencemeans greater ond polarity'

"hat element formsthe most polar ond

with caron(



,ypes of Chemical ;onds

• Depend on differences inelectronegativities'



!ormal Charge

• ) method of @eeping trac@ ofcharges'

• *hows what charge would eon what atom in a particular

<ewis structure'



"hy !ormal Charge(

• the most stale <ewis structurewill e the one with

?>ero formal charge'?the negative charge on themost electronegative atom'



Calculating !ormal Charge

• !or each atom in a valid <ewisstructure:

• Count the numer of valence electrons

• *utract all its nononding electrons• *utract half of its onding electrons

C

H

H

H

C

O

O P

O

OO

O

3-



Ionic *tructures

C

H

H

H N

H

H

H

+

Cl-

Na O CH3 or O CH3 Na+ _

X

,he N will have a 1formal charge

*alts E compounds of metalsand nonmetals E are ionic'



carocationcaranion

6uaternary ammoniumion

hydro.ideor [email protected]

halideion



Resonance

• "hen molecules or ions showcharacteristics of & or more valence

ond B<ewis dot structures whichdiffer from each other only in the placement of electrons'

• )nother of the maFor concepts inOrganic ChemistryG



Resonance *tructures

• Only electrons can e moved Busuallylone pairs or pi electrons'

• Nuclei positions and ond angles

remain the same'• ,he numer of unpaired electrons Bif

any remains the same'

• Resonance causes a delocali>ation ofelectrical charge'



Resonance -.ample

• ,he real structure is a resonance hyrid '•

)ll the ond lengths are the same'• -ach o.ygen has a 91H/ electrical charge'

N

O

OO

_ _

N

O

OO

_

N

O

OO



*ome -.amples of Resonance inOrganic Chemistry



,he 5aFor Resonance !orm

• has as many octets as possile'

• has as many onds as possile'

• has the negative charge on themost electronegative atom'

•has as little charge separation as possile'



Resonance 8yrid

maFor contriutor

minor contriutor+caron does

not have octet



*olved ro' 19&' !or each compound+draw the important resonance forms+

indicate which is the maFor contriutor+and whether all the forms have the same

energy'

a C8 /OC8 & J

C C

O

HH

H.. _



Chemical !ormulas

• !ull structural formulaBno lone pairs shown

• <ine9angle formula

• Condensed structuralformula

• 5olecular formula

• -mpirical formula

• C8 /COO8

• C & 8 0O &

• C8 & O

C

H

H

H

C

O

O H



rolem' *how the <ewis structure andline angle formula for the following

compounds'

a propane+ C /8 %

cycloutane+ C 08 %

c acetone+ C8 /CBOC8 /



)rrhenius )cids and ;ases

• )cids dissociate in water to give 8 / O D ions'

• ;ases dissociate in water to give O8 9 ions'

• K w L 8 / O D JO8 9 J L 1'3 . 13 910 at &0MC

• p8 L 9log 8 / O D J

• *trong acids and ases are 1337dissociated'

1 M 1 M

Cl-+H3O+

H2O+HCl



• issertation wor3 onconductiities ofelectrol!te solutions wasawarded lowest "assinggrade4 but was laterawarded the 1905 6obel&ri7e in *hemistr!8• &ro"osed the rstdenitions of acids andbases in 1::;.• -ormulated the conce"tof actiation energ! in

chemical r<ns.• &ro"osed his“greenhouse law” lin3ingatmos"heric leels of *O2

to earth’s tem"erature.'e was the “discoerer”

of global warming8

FYI: Svante Arrhenius (18"1#$%

http://upload.wikimedia.org/wikipedia/commons/6/6c/Arrhenius2.jpg



;r nsted9<owry )cids

and ;ases• )cids can donate a proton'

• ;ases can accept a proton'

• ConFugate acid9ase pairs'

CH3 C

O

OH + CH3 NH2 CH3 C

O

O-

+ CH3 NH3+

acid conFugatease

ase conFugateacid



5edical -.ample:

acid

ase

conFugate acid

conFugatease

Not asored in the

acidic stomach

)sored in theasic intestines



*tructural -ffects

on )cidity • -lectronegativity

• *i>e• Resonance staili>ation of conFugate

ase

-l t ti it ) idit f



Chapter 1

-lectronegativity )cidity of*econd Row 8ydrides

)s the ond to 8 ecomes more polari>ed+ 8 ecomes more positive andthe ond is easier to rea@'

) i *i ) idit f th



Chapter 1

)nion *i>e )cidity of the8alogen 8ydrides

• )s anion si>e increases+ the 8 is moreloosely held and the ond is easier to rea@'

• ) larger si>e also staili>es the anion'



Resonance )cidity •

Delocali>ation of the negative charge on the conFugatease will staili>e the anion+ so the sustance will e astronger acid'

• 5ore anionic resonance structures usually mean greaterstaili>ation and+ therefore+ more acidic B i'e' the anion

forms easier+ faster'

CH3CH2OH < CH3C

O

OH < CH3 S

O

O

OH

DRAW THE ANIONS OF THESE ACIDS.

< i ) id d ;



<ewis )cids and ;ases• <ewis acids accept electron pairs

L electrophile• <ewis ases donate electron pairs

L nucleophile

C d )



Curved )rrows

• "e use curved arrows to show

electron movement

• Curved arrows generally show electron

movement for pairs of electrons,he arrow starts where the electrons are

currently located

,he arrow ends where the electrons will end

up after the electron movement

C



Curved )rrows in Resonance

• Rule 1: never rea@ a single ond

• *ingle onds can rea@+ ut NO, in R-*ON)NC-

• Resonance occurs for electrons e.isting inoverlapping p oritals+ ut not in hyrid atomicoritals+ e'g' sp+ sp& + or sp/ '



Curved )rrows in Resonance

Rule &: Never e.ceed an octetfor & nd row elements B;+ C+ N+ O+ !

• -.amples of arrows that violate Rule &'

=ood arrow or ad arrow(



Important DefinitionsG

• -lectrophile E “lover of electrons”P willhave a partial or formal positive charge+ e'g' 8 ;r or R /C '

• Nucleophile E “nucleusHpositivecharge lover”P will have a partial or

formal negative charge+ e'g' N R / or E

O8'

̤

1 12 1 D t i hi h i



ro' 1912' 1 Determine which species areacting as electrophiles Bacids and which

are acting as nucleophiles Bases'& Qse the curved arrow formalism to showthe movement of electron pairs in thesereactions'

/ Indicate which reactions are est termed;ronsted9<owry acid9ase r.ns'

aCH3 H

O+ HCl

CH3 H

O+

H

+ Cl-

ro 1912 1 Determine which species are acting as electrophiles



ro' 1912' 1 Determine which species are acting as electrophilesBacids and which are acting as nucleophiles Bases'& Qse the curved arrow formalism to show the movement of electron

pairs in these r.ns'

/ Indicate which r.ns are est termed ;ronsted9<owry acid9aser.ns'

CH3 H

O

+ CH3O-

CH3

O-

O CH3

H

f CH

3 NH

2 + CH

3 Cl CH

3 NH

2

+CH

3 + Cl

-



,he -nd

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