Drawing 2D, 3D and Resonance Structures from condensed ...psbeauchamp/pdf/314_draw_2D_3D_FG_res.pdf · Drawing 2D, 3D and Resonance Structures from condensed line formulas. 1. Use

Beauchamp 2D / 3D structure drawing & Resonance

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Drawing 2D, 3D and Resonance Structures from condensed line formulas. 1. Use a condensed line formula to draw a 2D structure (and resonance structures). Smaller structures can use

the mechanical approach suggested below, larger structures will have to use organic intuition and knowledge

of functional groups.

2. Use your 2D structure (and resonance structures) to generate the 3D sigma skeleton. Each sigma bond counts

for 2 electrons.

3. Count all valence electrons (these electrons make up sigma and pi bonds, lone pairs and any radical centers).

4. Subtract sigma electrons from the total valence electrons (these are lone pair, pi and free radical electrons).

5. If there are excess electrons, add them in as lone pairs to fill valencies of most electronegative atoms first

(F > O > N).

6. If there are still excess electrons left add them to carbon atoms with the fewest sigma bonds. If there are still

excess electrons place them at alternate carbon positions to spread out electron density and minimize

electron/electron repulsion, as best you can.

7. If any atoms lack a full octet, look for adjacent lone pair electrons that can be shared. These will make pi

bonds. If there is more than one way to do this, there will be resonance structures. Draw as many of these as

are obvious. Any structures with full octets are usually OK (but, not necessarily the best resonance structure).

8. Evaluate formal charge on all of the atoms.

9. Evaluate resonance structures for relative contributions according to the following rules

a. More bonds and full octets are most important = best.

b. Having charge consistent with relative electronegativities is second best.

10. Write any additional resonance structures using typical resonance patterns of donor and acceptor sites (see

page 7).

a. alkene, alkyne and aromatic pi bonds are connector components and can donate or accept electrons

b. donor sites are atoms with lone pairs of electrons (and CC pi bonds from “10a”)

c. good acceptor sites are carbocation positions (empty 2p orbitals on carbon), cationic pi bonds and neutral

polar pi bonds (and CC pi bonds from “10a”)

11. To decide each atom’s 3D shape, hybridization and bond angles:

a. use a resonance structure where an atom has its maximum number of bonds (this shows the necessary 2p

orbitals to make any pi bonds (no pi bonds = sp3, one pi bond = sp2, two pi bonds = sp).

b. carbocation carbon atoms use an empty 2p orbital in our course.

c. subtract any 2p orbitals in pi bonds and cationic carbon from s, p, p, p. Whatever is left over is the

hybridization of the atom (whether C, N, O, S or halogens, in our course). (sp = linear, 180o, sp2 = trigonal

planar, 120o, sp3 = tetrahedral, 109o)



2D Structures – Generate 2D structures from condensed line formulas (R = generic organic portion). Very simple examples of the most common functional groups taught in first year organic chemistry are shown below. An example is provided for most of the functional groups on each end of a formula and in the middle of a formula. Simple 2D structures can be generated from condensed line formulas using the mechanical strategy described on page 1. However, more complicated 2D structures will require knowledge of common functional groups and common bonding patterns of the elements of organic chemistry (H, C, N, O, S and halogens).

RCO2H

RCH(CO2H)R'

CR

O

O H

HO2CR

C R

O

OH

CR

H

C

R'

OOH

carboxylic acids in condensed line formulas

on the right end

on the left end

in the middle

CR

O

O C

anhydrides in condensed line formulas RCO2COR'

O

R'

CR

O

O R'

RCO2R'

RCH(CO2CH3)R'

CR

H

C

R'

OO

R'O2CR

C R

O

OR'C

H

H

H

esters in condensed line formulas

RCOCl ClOCR

CR

O

Cl C R

O

Cl

CR

H

C

R'

OCl

acid chlorides in condensed line formulas RCH(COCl)R'

RCONH2

CR

O

N H

H

C R

O

NH

H

H2NOCR

RCH(CONH2)R'

CR

H

C

R'

ONH

H

amides in condensed line formulas

RCONHR'

CR

O

N R'

H



nitriles in condensed line formulas

RCN

RCH(CN)R'

NCR

CR N C RN

CR

H

C

R'

N

aldehydes in condensed line formulas

RCHO

RCH(CHO)R'

OHCR

CR

O

H C R

O

H

CR

H

C

R'

OH

ketones in condensed line formulas

RCOR'

RCH(COCH3)R'

ROCR'

CR

O

R' C R'

O

R

CR

H

C

R'

OCH

HH

alcoholes in condensed line formulas

RCH2OHRCHOHR'

CR

H

H

O

CR

H

O

R'H

H

HOCHCH3R

C R

H

C

O

H

H

H

H

thiols in condensed line formulasRCH2SH

RCHSHR'

CR

H

H

S

CR

H

S

R'H

H

HSCHCH3R

C R

H

C

S

H

H

H

H



amines in condensed line formulas

RCH2NH2RCHNH2R'

CH3HNCH2R

CR

H

H

N

H

C R

H

H

N

CR

H

N

R'

HH HH

C

H

H

H

ethers in condensed line formulas

RCH2OCH3 RCH(OCH3)R'

CR

H

H

O C

H

H

H

CR

H

O

R'

C

H

HH

RCHCH3SCH3 RCH(SCH3)R'

CR

H

C

S C

H

H

H

CR

H

S

R'

C

H

HH

sulfides in condensed line formulas

H H

H

nitro compounds in condensed line formulas

RCH2NO2

RCH(NO2)R'O2NCH2R

CR

H

H

N

O

O

C R

H

H

N

O

O

CR

H

N

R'

OO

nitroso compounds in condensed line formulas

RCH2NORCH(NO)R'

ONCH2R

CR

H

H

N

O

C R

H

H

N

OCR

H

N

R'

O

azido compounds in condensed line formulas

RCH2NNN

RCH(N3)R'

NNNCH2R

CR

H

H

N

N

C R

H

H

N

NCR

H

N

R'

N

N N

N



diazo compounds in condensed line formulas

RCHNNNNCHR

CR

H

N N CR

H

N N C R

H

NN C R

H

NN

alkenes in condensed line formulas (E and Z configurations are possible)

RCHCH2 RCHCHR'

CR C

H

H

H

CR C

H

R'

H

C RC

H

H

H

H2CCHR

RCHCCH3R'

CR C

H

R'

CH

H

H

alkynes in condensed line formulas

RCCH RCCR'

CR C H CR C R'C RCH

HCCR

aromatics in condensed line formulas (different substitution patterns are possibilities)RC6H5 R(C6H4)R'

C C

C

CC

CR

H H

H

HH

CC

C

C C

C R

HH

H

H H

H5C6R

CC

C

C C

C R'

HH

R

H H

orthometapara

halogen compounds in condensed line formulasRBr RCHBrR'

CR

H

H

Br CR

H

Br

R'

RBr

C R

H

H

Br



The following are examples of small molecules and ions using 2D and 3D formulas. (2D sketch, just below)

C6H5CH3 C6H5CH2 C6H5CH2

C6H5NH2 C6H5NH3 C6H5NH

C6H5OH C6H5OH2C6H5O

CH3NO2 CH3NO2H CH2NO2

CH3NO CH3NOH CH2NO NNNONOOCO

NO3 NO2HNO3 HNO2

CH2CCH2

CH2CNH CH2CNH2

CH2CO CHCOCH2COH

CH2NN CH3NNN

HH

C6H5F C6H5FH

CH2CN CO CN OO

CH3CO2H CH3CO2H2 CH3CO2

CH3CO2CH3

CH3CHO CH3CHOH CH2CHO

CH3COCH3 CH3COHCH3

CH3CO(OH)CH3 CH2CHO2CH3

CH3COCH2

a

b

c

d

e

f

g

h NN FF

a

C

H

H

C

H

H

C

H

H

HC

H3C

O

OH C

H3C

O

OH C

H3C

O

O

H

b

N

H

H

N

H

H

N

H

HC

H3C

O

OCH3 C

H3C

O

OCH3

H

CH2C

O

OCH3

c

O

H

O

H

H

O CH3C

O

HC

H3C

O

H

H

CH2C

O

H

d

F F

H

CH3C

O

CH3

CH3C

O

CH3

H

CH2C

O

CH3

e

NH3C

O

O

NH3C

O

O

NH2C

O

O

H

CC C

H

H

H

H

NC N

H

H NH3C N

N

f

NH3C

O

NH3C

O

NH2C

OH

NN

NC

O

O

NO

O

g

CH2C O CH2C O CC O

H

H NO

O

O

H

NO

O

ONO

OH

NO

O

hCH2C N CH2C N CC N

H

H

H H

H

H H C O C N OO FFN N



Common, Possible Patterns of Resonance Used in Drawing 2D and 3D Organic Structures

There are four common resonance patterns that we encounter, using two donor sites and two acceptor sites. Donor electrons (D) can come from lone pairs and pi bonds. Acceptor sites (A) include an empty 2p orbital (almost always carbon in our course = carbocations) and pi bonds (CC is OK, polar is good, ionic polar is best). Notice that CC pi bonds can donate and accept electrons. In our course resonance systems will always occur through p orbitals. There is another brand of resonance that can use sigma bonds (usually C-H) with p orbitals, called hyperconjugation. We will not emphasize this resonance.

Resonance Pattern 1 – Lone pair donation (2p orbital) into an empty 2p orbital (carbocation or pi cation).

Resonance Pattern 2 – Lone pair (2p orbital) donation into pi bonds (many kinds).

Resonance Pattern 3 – Pi bond donation (from alkene, alkyne or aromatic) into an empty 2p orbital (carbocation or pi cation).

Resonance Pattern 4 – Pi bond donation (from alkene, alkyne or aromatic) into a pi bond acceptor (alkene, alkyne, aromatic, carbonyl, imine, nitrile, etc. Polar is better.)

Donorslone pairs

X: = N, O, F; X: = C ,N ,OCC pi bonds

(alkenes, alkynes, aromatics)

empty 2porbitals

(on carbon)

pi bonds(all kinds)

Acceptorspattern 2

pattern 3pattern 1

pattern 4

X C X C

CC

N CC

N

CC

C CC

C

CC

O

CC

C

O

C

X C

O

X C

OH H

ionic pi cation

OC

N OC

N

ionic polar bonds are best

CC

CO

CC

CO

H H

polar is better

CCC

CCC

N N

simple carbocation simple carbocation

CC pi bonds are OK

polar pi bonds are better

OC

N OC

N

H H

CCC

CCC

C C

H H

CC pi bonds are OK

ionic polar bonds are best

H H

ionic pi cation



1. Donor = lone pair next to empty 2p orbital acceptors (usually on carbon as a carbocation)

X C

CH2H2N

CH2HO

CH2F

CH2NO

CH2NHN

CH2NH2C

CH2HN

CH2O

CH2H2C

CH2N

CHO

CF

CH2

CH2

CH2

CHN

CO

CH2C

CH2

CH2

CH2

CHN

CO

CH2C

O

O

O

X C X C X C

sp or sp2 hybridization is possible on either X or C, see examples below.

Many other examples are possible.

CH2N O

CHO O

cation neutral

cations neutrals

X = N, O, F

X = C , N , O

CH2N N H

both sides can donateCO O

both sides can donate

H

X = N, O, F

X = C , N , O

2. Donor = lone pair next to pi bond acceptors (CC bonds are OK, polar pi bonds are good and ionic pi bonds are best).

X C

C

X C

C

X C

C

X C

C

CH2C

R

O

CHN

R

O

CO

R

O

CH2N

R

O

CHO

R

O

CF

R

O

CH2C

R

O

CHN

R

O

CO

R

O

R

H

H

CH2C

R

NH2

CHN

R

NH2

CO

R

NH2

CH2C

R

N

CHN

R

N

CO

R

N

R

H

H

sp or sp2 hybridization is possible on either X or C, see examples below.

anions neutrals

Many other examples are possible.



3. Donor pi bonds (usually alkene, alkyne or aromatic) next to empty 2p orbital acceptors (usually on carbon as a carbocation)

CC C

R

R

R R

R CC C

R R

RCR C C

R

R

C C

R

R

R

C R

R

C C

R

R

R

C

R

R

resonance, etc. resonance, etc. resonance, etc.

4. Donor pi bonds (usually alkene, alkyne or aromatic) next to a polar other pi bond acceptors (CC are OK, polar pi bonds are good (C=N, C=O, N=N, N=O, nitrile), and ionic pi bonds are best.

Just a few examples. Many more variations are possible.

CC

CO

R

R

R

R

CC

C

R

R

RN

CC

CO

R

R

R

R

CC

C

R

R

RN

H

H

alkene or aromatic

CC

CO

R

R

R

R

CC

CO

R

R

R

R

CC

C

R

R

RN

CC

C

R

R

RN

CC

CO

R

R

R

R

CC

CO

R

R

R

R

CC

C

R

R

RN

CC

C

R

R

RN

H

H

H

H

alkene or aromatic alkene or aromatic alkene or aromatic

polar pi bondsionic polar pi bonds



antidisestablishmenttarianism = opposition to disestablishment of a church or religious body (how do you say it?)

Break a complicated problem into its

simpler parts

an-ti-dis-es-tab-lish-ment-tar-i-an-ism

OHCCHC(CH3)COC6H4CO2CH(NO)CHOHCH(OCH3)CHCNCONHCH(NO2)CO2H

OHCCHC(CH3)COC6H4CO2CH(NO)CHOHCH(OCH3)CHCNCONHCH(NO2)CO2H

C6 ring has formal charge

C C

O

H

H

C

CH

HH

C

O

C

C C

C

C C

C

HH

HH

O

O C

H

NO

C

O

H

H

C

O

C

H

C

C

N

H

C

O

N

H

C

NOO

H

C

O

O H

Complex condensed line formula (Use your chemical intuition.)

2D structure

Functional group breaks

H H

H

(CH3)3CCCCOCHCNCH(CHO)CH(COCl)CH(CO2CH3)CH(CONH2)NHCH2CONHCH2C6H4CH(COCH3)CH(NO2)-

-CHNH2CO2CHBrCH(NH3)CH(CO2H)CHSHCH(SCH3)CHOHCH2SCH2CHCHCH(CH2OH)CH2OCH2CH(CO2)CHO

has formal chargeC6 ringCondensed line formula with functional group breaks

2D structure

C

CH

HH

C

H

H

H CH

H

H

C C C

O

C

H

C

N

C

H

C

O H

C

C

O

H

C

H

C

O O

CH

H

H

C

H

C

O N

HH

N

H

C C

H

O

N

H

C

H

H

C

C C

C

C C

C

H

CO

HH

H H

C

C

HHH

H

NO O

continue

continue C

H

N

C

H H

O

O C

Br

C

H

H

C

O O

C

H

H

S

H

C

S

C

H H

H

H

C

H

OH

C

H

H

S C

H

H

C

H

C

H

C

H

C

CH H

O

H

H

H

O C

H

H

C

C

H

O H

C

O

O

Cl

C

N

HH

H

H

alkyne

ketone

nitrile

aldehyde ester

acid chloride amide

amide

aromaticketone

nitro

ester

amine

bromo

ammonium ion

carboxylic acid

thiol

sulfide

alcohol

sulfide

alkene

alcohol

ether

aldehyde

carboxylate

amineH



3D Problems

Example 1

HNCCHCCH3CCCO2CH(CH3)2

NH C C

H

C

CH

H

H

C C C

O

O C

H

C

C

H

H

HH

HH

NH C C

H

C C

C

C C

O

O CH

HH

H

CC

NH C C

H

C

CH3

C C C

O

O C

H

CH3

CH3

NH C C

H

C

CH3

C C C

O

O C

H

CH3

CH3

NH C C

H

C

CH3

C C C

O

O C

H

CH3

CH3

NH C C

H

C

CH3

C C C

O

O C

H

CH3

CH3

NH C C

H

C C

C

C C

O

OH

HH

Template structure can be used to draw all resonance structures above. On an exam draw out all hydrogens. You should be able to specify the hybridization, shape, bond angles, number of sigma bonds, number of pi bonds and number of lone pairs on every nonhydrogen atoms.

resonance

resonance

resonanceseparate

resonanceusing ester

alkoxy oxygen

H

HH

HH

H

C

H

CC

H

HH

HH

H

3D representation of A

A

B C

DE

Template



Example 2

HOHCCCC(CHO)C(OCH3)NH2

C

O

H

C

H

C C

C

C

N

O

O H

C

H

H

HH H

C C C

C

C O

N

O

H

H

H

CH

HH

=

3D of first structure

O

H

C C

H

C C

C H

C

O

N

O

H

H

C

H

H H

C

O

H

C

H

C C

C

C

N

O

O H

C

H

H

HH H

resonance

resonance C

O

H

C

H

C C

C

C

N

O

O H

C

H

H

HH H

resonance

C

O

H

C

H

C C

C

C

N

O

O H

C

H

H

HH H

resonanceC

O

H

C

H

C C

C

C

N

O

O H

C

H

H

HH H

resonance

C

O

H

C

H

C C

C

C

N

O

O H

C

H

H

HH H


A

B C

DE

F

Template

at various locations

O

H

C

H



2D / 3D resonance structures with formal charge

N

H

H C

H

H

C

H

H

O C

H

H

C

H

H

C

O

C

H

C C C

C

C C

C

C

C N H

HH

HH

NH2CH2CH2OCH2CH2C(O)CHCCC6H4CNH

N

H

H C

H

H

C

H

H

O C

H

H

C

H

H

C

O

C

H

C C C

C

C C

C

CH

C N H

HH

HH

N

H

H C

H

H

C

H

H

O C

H

H

C

H

H

C

O

C

H

C C C

C

C C

C

C

C N H

HH

HH

N

H

H C

H

H

C

H

H

O C

H

H

C

H

H

C

O

C

H

C C C

C

C C

C

C

C N H

HH

HH

N

H

H C

H

H

C

H

H

O C

H

H

C

H

H

C

O

C

H

C C C

C

C C

C

C

C N H

HH

HH

sigma skeleton

Example 3

next page




N

H

H C

H

H

C

H

H

O C

H

H

C

H

H

C

O

C

H

C C C

C

C C

C

C

C N H

HH

HH

N

H

H C

H

H

C

H

H

O C

H

H

C

H

H

C

O

C

H

C C C

C

C C

C

C

C N H

HH

HH

previous page

C

C

C C

C C

C

C C

C

HH

H H

Example 3 (3D)

N HC

H

O

CC

OC

CN

HH

H H H

H

HHH

H



HOCH2CH2NHCHCHCCC6H4COHNH2

OH C

H

H

C

H

H

N C

H

C

H

C C

C

C C

C

C

C N H

HH

HH

C

O

H

HH

OH C

H

H

C

H

H

N C

H

C

H

C C

C

C C

C

C

C N H

HH

HH

C

O

H

HH

sigma skeleton

OH C

H

H

C

H

H

N C

H

C

H

C C

C

C C

C

C

C N H

HH

HH

C

O

H

HH

OH C

H

H

C

H

H

N C

H

C

H

C C

C

C C

C

C

C N H

HH

HH

C

O

H

HH

Example 4

OH C

H

H

C

H

H

N C

H

C

H

C C

C

C C

C

C

C N H

HH

HH

C

HO

H

HH

next page

at various locations



OH C

H

H

C

H

H

N C

H

C

H

C C

C

C C

C

C

C N H

HH

HH

C

O

H

HH

previous page

OH C

H

H

C

H

H

N C

H

C

H

C C

C

C C

C

C

C N H

HH

HH

C

O

H

HH

OH C

H

H

C

H

H

N C

H

C

H

C C

C

C C

C

C

C N H

HH

HH

C

O

H

HH

OH C

H

H

C

H

H

N C

H

C

H

C C

C

C C

C

C

C N H

HH

HH

C

O

H

HH

Example 4 (3D)

CC C C

C C

C

C C

C

O

N

H

H

HHH

H H

H

C

H

Example 4 template, can be used for all resonance structures.

N

H

CC

OH

H H

H H

The first and last resonance structures are best according to our rules.



Additional structure Example 5 (2D and 3D)

(CH3)2NCCC(OCH3)CHCOHCH3

H C N C C C C

O

C H

H

H

C

C

sigma skeleton

HH

H

H

H

O

C

HH

H

H

H

N

C

C

C C C

C

O

H

C

C

O

C

H

H

H

H

H

HH

H

H

H

H

H

H

3D template

H C N C C C C

O

C H

H

H

C

CH

HH

H

H

O

C

HH

H

H

H

add in pi bonds and lone pairs

H C N C C C C

O

C H

H

H

C

CH

HH

H

H

O

C

HH

H

H

H

H C N C C C C

O

C H

H

H

C

CH

HH

H

H

O

C

HH

H

H

H

H C N C C C C

O

C H

H

H

C

CH

HH

H

H

O

C

HH

H

H

H

H C N C C C C

O

C H

H

H

C

CH

HH

H

H

O

C

HH

H

H

H

H C N C C C C

O

C H

H

H

C

CH

HH

H

H

O

C

HH

H

H

H

at various locations A

BC

D E

F

F > A = D > B = C = E



CH3CH2CH3 CH3CH2CH2 CH3CH2CH2 CH3CH2CH2

CH3CHCH3 CH3CHCH3CH3CHCH3

CH C

CH

H H H H

H H

use zig-zag drawingfor sp3 chains

CC

H

HCH

H H

H H

CC

H

HCH

H H

H H

CC

H

HCH

H H

H H

1o carbocation 1o carbanion 1o free radical

CC

C

HH

H H

2o carbocation

H

H H

2o carbanion 2o free radical

CC

C

HH

H H

H

H H

CC

C

HH

H H

H

H H

alkane

H3C

H2C

CH3

alkane

CH3CH2OH CH3CH2OH2CH3CH2O

CH C

OH

H H

H H

use zig-zag drawing

for sp3 chains

CH C

OH

H H H

H Halcohol

CH C

O

H H

H H

alkoxideprotonated alcohol

CH3OCH3 CH3OHCH3

CH O

CH

H H


CH O

CH

H H H H

Hether

protonated ether

H H



CH3NHCH3CH3NH2CH3 CH3NCH3

CH N

CH

H H

H


CH N

CH

H H H H

H H2o amine

CH N

C

H H H H

2o amide aniondialkylammonium ion

H H

H

CH2CHCH3 CH2CHCH2 CH2CHCH2 CH2CHCH2

C

H

C

C

HH

H

H H

monosubstituted alkene

C

H

C

C

HH

H

H

C

H

C

C

HH

H

H

resonance

1o allylic carbocation

C

H

C

C

HH

H

H

C

H

C

C

H

H

H

resonance

1o allylic carbanion

C

H

C

C

HH

H

H

C

H

C

C

H

H

H

resonance

1o allylic free radical

H H

H2C

HC

CH3



CH3CHO CH3CHOH CH2CHO

O C

C

H

H

H H

aldehyde resonance

O C

C

H

H

H

O C

C H

H

resonance

enolate anion

H

O C

C

HH

H

H H

O C

C

HH

H

H Hprotonated carbonyl

CH3COCH3 CH3COHCH3 CH3COCH2

O C

C

C

H

H Hketone resonance

O C

C H

H

O C

C H

H

resonance

enolate anion

O C

C

H

H

H H

O C

C

H

H

H Hprotonated carbonyl

H

H

HC

H

H

H

C

H

H

H

C

H

H

H

C

H

H

H



HCCCH3 HCCCH2 HCCCH2 HCCCH2

C C CHC C CH

H

HH

alkyne

H

H

C C CHH

H

propargyl carbocation

resonance

C C CHH

H

C C CHH

H

propargyl carbanion

resonance

C C CHH

H

C C CHH

H

propargyl free radical

resonance

CH C CH3

CH3CN CH3CNH CH2CN

N C C N C CH

H

HH

nitrile

N C CH

protonated nitrile

resonance

N C CH

H

N C CH

H

nitrile enolate

resonance

CN CH3

H

H

H

H

HH



CH3CO2H CH3C(OH)2 CH3CO2 CH2CO2

-2

O C

CH

H H

carboxylic acid

O C

C H

H

O C

C H

Hresonance

carboxylate anion

O

H

O

H

C

CH

H H

protonated carboxylic acid

O

H

resonance

O

H

C

CH

H H

O

H

O

H

C

CH

H H

O

H

resonance

O C

CH

H H

O

O C

CH

H H

O

resonance

O

O

O C

C H

H

O

carboxylate dianion

resonanceH3C

C

O

OH

CH3CONH2 CH3COHNH2 CH3CONH

O C

CH

H H

1o amide

amide anion

N H

H

O

H

C

CH

H H

protonated amide

N H

H

resonance

O

H

C

CH

H H

N H

H

O

H

C

CH

H H

N

Hresonance

O C

CH

H H

N H

O C

CH

H H

N

resonance

H

H

H3CC

O

NH2



CH3COCl CH3COHCl CH2COCl

O C

CH

H H

acid chloride

acid chlorideenolate

(unstable to elimination,forms ketene)

Cl

O

H

C

CH

H H

Poor resonance due to inefficient overlap of 3p chlorine orbital with 2p carbon orbital. Even worse for Br and I.

Cl

H

resonance

O

H

C

CH

H H

Cl

H

O

H

C

CH

H H

Cl

Hresonance

O C

C H

H

O C

C H

H

resonance

Cl

Cl

H3CC

O

Cl



C6H5CH3 C6H5CH2 C6H5CH2 C6H5CH2

C

C

C

C

C

C

H H

HH

CH

H

H

H

C

C

C

C

C

C

H H

HH

CH

H

H

resonance

C

C

C

C

C

C

H H

HH

CH

H

H

resonance

C

C

C

C

C

C

H H

HH

CH

H

H

resonance

C

C

C

C

C

C

H H

HH

CH

H

HC

C

C

C

C

C

H H

HH

CH

H

HC

C

C

C

C

C

H H

HH

CH

H

H

resonance2 more times

(around the ring)


(around the ring)


(around the ring)

C C

C

CC

C CH3

HH

H

H H

aromatic

CH3CH2F

CH C

F

H H

H H


fluoroalkane

C

F

H

C C

F

resonance

H

CH3CH2FH

H

H

H

C

H

H

HH3C

H2C

F

CH3CO2COH3

O C

C

anhydride

O C

H

H3CC

O

OC

O

CH3

O

CH

HHH

HH

Documents

Drawing 2D, 3D and Resonance Structures from condensed ...psbeauchamp/pdf/314_draw_2D_3D_FG_res.pdf · Drawing 2D, 3D and Resonance Structures from condensed line formulas. 1. Use