235 – organic ii eactions onjugated ienes · 1 suggest a synthesis for each of the compounds...

© ChemistryOnline, 2009-2014

Suggest a synthesis for each of the compounds shown on the right using the method shown under the compound.

Clearly show reagents/reactants required next to the numbers on the arrow; you may add additional "numbers" if

necessary. (4 points per box )

an acetoacetic ester synthesis

1.

2.

CH3

OCH3

OCH2CH3

OO

+

an intramolecular aldol condensation

1.

2.

O

O

a Claisen condensation

1.

2.

H

O

an aldol condensation

1.

2.

alkylation of an enamine

O

1.

2.

Br

9.

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235 – Organic II Final Exam Review

Chemistry 235, Fall 2014 - Sample Second Hour Exam Section I – Nomenclature & M/C (4 points each) In the space provided, give the correct IUPAC name for the compound shown on the right.

1. __________________________________________________ 2. __________________________________________________ 3. __________________________________________________ 4. Which of the compounds shown below would be most consistent with the following 13C spectral data:

quartet, 22.0 ppm; quartet, 50.0 ppm; doublet, 129.1 ppm ; singlet, 127.5 ppm; doublet, 129.7 ppm;

singlet, 142.8 ppm; singlet, 167.0 ppm

5. In the tetrahedral intermediate formed in an acyl transfer reaction, the best anionic leaving group will be:

a. the strongest base b. the most stable anion c. the group with the highest pKa d. the phenoxy group e. the group having the weakest conjugate acid

6. Which of the following is correct regarding the spectroscopy of acyl compounds?

a. the frequency of the carbonyl absorbance of acyl compounds in the IR generally parallels reactivity of the

acyl carbonyl towards nucleophilic addition b. in the mass spectrum, the most common fragmentation of acyl compounds is expulsion of carbon monoxide

c. the 1H NMR absorbance of carboxylic acid protons is very highly deshielded

d. a and c, only, are correct statements e. a, b and c are correct statements

O

OH

O

O

O

Cl

a.

b.c.

d.e.

O

H

OCH3

H3C

O CH3

O

O

OCH3

OH3CO

CH3

O

Cl

CH3O

21. Data for the mass spectrum, the 1H and 13C NMR and the IR spectrum for a compound C9H10O are given below.

Based on the spectral information provided, suggest a structure for this compound and write the structure clearly in the

space provided below. Also, in the spaces provided, clearly indicate the information which you obtained from each

spectral source. (5 points for each spectrum, 5 points for the correct structure; 25 points total)

1H NMR

Infrared Spectrum

Mass Spectrum

Structure:

Chapter 5: INTEGRATED SPECTROSCOPY PROBLEMS 85

Compound 27 is a neutral, low-melting solid (melting point 22-24 ˚C). The Mass, IR, and 1H NMR spectra, along with 13C NMR

data, are given below. Elemental Analysis: C, 80.56; H, 7.51; O, 11.92.

13C Spectral Data:

singlet, 196.5 ppm

singlet, 142.1 ppm

singlet, 134.4 ppm

doublet, 129.1 ppm

doublet, 128.5 ppm

quartet, 22.8 ppm

quartet, 20.9 ppm

ppm, δ

7 6 5 4 3 2 1 0

2 2

3

3

m/e30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

Inte

nsity

91

65

119

134

4000 30001500 1300

200025001200 1100 1000 900 800 700

3 4 5 6 7 8 9 10 11 12 13 14 15

Wave Number, cm -1

Wavelength, microns

Abso

rban

ce

a.

b.c.

d.e.

CH3

CH2

Chemistry 235 – Sample First Hour Exam

All multiple choice and short answer questions are 3 points each; others as marked.

1. In the space below, write an acceptable IUPAC name for the molecule shown on the right:

______________________________________________________________


______________________________________________________________


______________________________________________________________

4. Which of the following is true regarding the 13C NMR of carbonyl compounds:

a. in the proton-coupled 13C NMR, aldehyde carbons will appear as doublets

b. aldehydes and ketones will typically absorb at values ≈ 200 ppm

c. the carbonyl absorbance from a ketone will always appear as a singlet

d. answers a) and c), only, are correct. e. answers a), b) and c) are all correct. 5. Chlorine exists as two major isotopes; 35Cl, 75%, and 37Cl, 25%. In the mass spectrum, a compound with one

chlorine atom will have: a. two molecular ions, in the ratio 3:1 b. four molecular ions, in the ratio 1:3:3:1 c. two molecular ions, in the ratio 2:1 d. two molecular ions, in the ratio 1: 1 e. three molecular ions, in the ratio 1:2:1 6. The base peak in the mass spectrum of toluene, , is most likely to be due to:

7. The major bands in the infrared spectrum of benzyl alcohol will be:

a. 3150 cm-1; 2200 cm-1; 1610 cm-1; 1450 cm-1

b. 3450 cm-1; 3100 cm-1; 2930 cm-1; 1760 cm-1

c. 2930 cm-1; 2450 cm-1; 1610 cm-1 d. 3450 cm-1; 3100 cm-1; 2930 cm-1; 1600 cm-1 e. 3450 cm-1; 3100 cm-1; 2200 cm-1; 1600 cm-1 8. Which of the following is not true regarding the spectra of 4-methylbenzonitrile:

a. in the 1H NMR, the phenyl group will appear as two doublets

b. the 13C NMR will have two singlets and two doublets in the “aromatic region”

c. the IR spectrum will display by a significant absorption at about 2200 cm-1

d. in the 1H NMR, the CH3 group will absorb at approximately 2.2 ppm

e. in the mass spectrum, the base peak will most likely be at m/z = 91

CH2OH

CNCH3

CH3

CH3

NO2

Br

CH3

CH2CH3

CH3


+ HBr

Br

Br

1,2 addition

1,4 addition

12

3

4

Just like alkenes, conjugated dienes undergo the ionic addition of HBr; however, the addition to conjugated dienes proceeds by two pathways.

REACTIONS OF CONJUGATED DIENES


CH2

H

δδ

Br-

CH2

Hallylic carbocation

Br

CH2

H

+ HBr

In the 1,4-addition, protonation on the terminal carbon generates the allylic carbocation, with cationic character on both carbons #1 and #3.



CH2

H

δδ

Br-

CH2

Hallylic carbocation

Br

CH2

H

+ HBr

In the 1,4-addition, protonation on the terminal carbon generates the allylic carbocation, with cationic character on both carbons #1 and #3.


The addition of Br– to carbon #1 of the diene gives the 1,4-addition product.


•  The 1,2-addition product forms rapidly at low temperatures.

•  The 1,4-addition product is predominant at higher temperatures.

•  Even at low temperatures, 1,4-addition products will predominate if given enough time.

•  The addition of HBr to butadiene is reversible and isolated 1,2-addition product will convert to the 1,4-product at higher temperatures or at longer times.

For 1,2 and 1,4-additions the following trends are observed:

1,2 VS 1,4 ADDITION REACTIONS OF CONJUGATED DIENES


+ HBr

Br

Br

1,2 addition

1,4 addition

12

3

4

The two products are also referred to as the kinetic product; and the thermodynamic product.


Kinetic product (faster).

Thermodynamic product (slower, but more stable).


Cl2/CCl4

HBr1,2-addition

HBr1,2-addition

HBr1,2-addition

HBr1,2-addition

HBr1,4-addition

HBr1,4-addition

HBr1,4-addition

HBr1,4-addition

Predict the major products for the following reactions:

IN-CLASS PROBLEM


+heat

+heat

+heat

O

CH3

CO

CH3

a diene......and a dienophile

The Diels-Alder reaction; 4 + 2 Cycloadditions.


This is called an electrocyclic reaction.


+heat

+heat

+heat

O

CH3

CO

CH3

The Diels-Alder reaction; 4 + 2 Cycloadditions.



THE (4N + 2) RULE

The resonance description of benzene will explain the geometry of the molecule and the isomer distribution of benzene derivatives, but does not explain the unusual stability of benzene and its derivatives.

The stability of benzene is suggested to arise from the fact that the conjugated π system is planar and contains 4n + 2 electrons (with n = 1), and it is suggested that all compounds having planar, conjugated π systems containing 4n + 2 electrons will share this stability. This property, described originally by Hückel, is referred to as aromaticity.


THE (4N + 2) RULE

Consider the following molecules:


4 π electronsnot aromatic

6 π electronsaromatic

8 π electronsnot aromatic


THE (4N + 2) RULE

Consider the following molecules:



CH3

CH2CH2CH3

MnO4-/H2O, heat

MnO4-/H2O, heat

MnO4-/H2O, heat

REACTIONS OF AROMATIC SIDE-CHAINSOxidation with neutral MnO4

-


MnO4-/H2O, heat

COOH

COOH

CH3

CH3

MnO4-/H2O, heat

COOHCOOH

REACTIONS OF AROMATIC SIDE-CHAINS


NBS/CCl4"radical initiator"



CH2CH2CH3

CH3

Br

CHCH2CH3Br

CH2 Br

REACTIONS OF AROMATIC SIDE-CHAINSAllylic bromination with NBS


Li/NH3

CH3 Li/NH3CH3

OCH3 Li/NH3OCH3

Dissolving Metal Reduction of Benzene DerivativesThe Birch Reduction



Predict the products of the following reactions


COOHHOOC

Br

Br

MnO4-/H2O

Predict the products of the following reactions.

Li/NH3



Acylation

Alkylation

Sulfonation

Nitration

Halogenation

C

O

R

R

SO 3 H

NO 2

X

X+

NO2+

HSO3+

R+

RC≣O+

ELECTROPHILIC AROMATIC SUBSTITUTION


HALOGENATION REACTIONS

FeBr

Br

Br

Br Br

Br2/FeBr3

Br2/AlBr3

Br

H

Br

ClCl2/FeCl3

Cl2/AlCl3

Cl

H


NITRATION REACTIONS

HNO3

H2SO4

NO2NO2

H

H2SO4 + HNO3 NO2+ + H2O


SULFONATION REACTIONS

SO3

H2SO4

H2SO4 + SO3 HSO3+ + HSO4

-

SO3HSO3H

H


FRIEDEL-CRAFTS ALKYLATION

CH3Br

FeBr

Br

Br

Br CH3

FeBr3

CH3CH3

H


FRIEDEL-CRAFTS ALKYLATION

FeBr

Br

Br

Br CH3

1. Reaction limited to alkyl halides; aryl or vinyl halides do not react.

2. Reaction does not occur on rings containing strong electron withdrawing substituents.

3. Multiple substitutions often occur. 4. Carbocation rearrangements can occur, particularly

with 1˚ alkyl halides.

NO2 CN SO3H CHO C

COOH COOR NR3+

O

R


FRIEDEL-CRAFTS ACYLATION

FeBr3

Br C

O

CH3

O

C

CH3

FeBr

Br

Br

BrC

O

CH3C

O

CH3

C

H

O

CH3


FRIEDEL-CRAFTS ACYLATION

1. Multiple substitutions do not occur.

2. Carbocation rearrangements do not occur.

3. Reaction does not occur on rings containing strong electron withdrawing substituents.

4. Acid anhydrides can also be used.

H3C O CH3

O O

Br C

O

CH3

O

C

CH3

FeBr

Br

Br


1.(con't) Predict the products of the following reactions.

AlCl3

O

O O

FeCl3

Cl2

SO3/H2SO4

IN-CLASS PROBLEM

Cl


NO2CN

SO3H

CHO

CORCOOHCOOR

NR3+

NH2

OCH3

OH

NH

CO

CH3CH3

FBr

ClI

H

Strongly Activating

Strongly Deactivating

REACTIVITY OF SUBSTITUTED BENZENES

ortho & para

directing

meta directing


CH3

SO3H

NO2

Br2/FeBr3

I2/CuCl2

Cl2/FeCl3

IN-CLASS PROBLEM:


CH3

SO3H

NO2

Br2/FeBr3

I2/CuCl2

Cl2/FeCl3CH3

Cl

SO3HBr

NO2I

+ ortho isomer

CH3

CH(CH3)2

ClSO3/H2SO4

excess HNO3/H2SO4

ClOC

AlCl3

CH3

NO2

O2N NO2

CH(CH3)2

O

Cl

HO3S+ ortho isomer

IN-CLASS PROBLEM


O

O

H

O

CH3

HO H

H

OHH

CH3

HO H

1. BH4-

2. H3O+

1. BH4-

2. H3O+

1. BH4-

2. H3O+

IN-CLASS PROBLEM

Reactions that yield alcohols:


CH3O

O

HO

H H

OOH

H

O

OH OH

H H

1. LiAlH4, ether

2. H3O+

1. LiAlH4, ether

2. H3O+

1. LiAlH4, ether

2. H3O+

IN-CLASS PROBLEM



IN-CLASS PROBLEM


O

H

O

1. Mg/ether 2. H3O+

1. Mg/ether 2. H3O+

1. Mg/ether 2. H3O+

Br

+

+ CH3Br

Br+

H

CH3

O


H

OH

OH

OH

1. Mg, ether 2. H3O+

1. LiAlH4, ether

2. H3O+

1. LiAlH4, ether

2. H3O+

from a carboxylic acid

from an ester

from an ester

OCH3

O

OH

O

BrBr

H OCH3

O

+

IN-CLASS PROBLEM



OH

Suggest two syntheses for the molecule shown below, using a Grignard Reaction.

IN-CLASS PROBLEM


CH3

CO

H

CH2OHBr

CHO

O

O

H O

O

O

OH

Br CH2OH

IN-CLASS PROBLEM

Utilizing any one of the starting materials shown on the right, suggest a synthesis of the following compound:


H OH

CH3

CO

H

CH2OHBr

CHO

O

O

H O

O

O

OH

IN-CLASS PROBLEM

Utilizing any one of the starting materials shown on the right, suggest a synthesis of the following compound:


O

O

CH3 O

CH2CCH O

1. Predict the products of the following substitution reactions.

CH2Br

CH2Br

H C C CH2OTos

CH2--OCH3

O

IN-CLASS PROBLEM

Predict the products for the following substitution reactions.


CH2CH3

O

OOH1.

2. H+/H2O

1. CH3CH2O-

2. H+/H2O

MgBr, ether

CH2CH3

H

OHOHH+/H2O

OOH

O

IN-CLASS PROBLEM

Predict the products for the following reactions of epoxides.


OCH3

CH3

CH2 Br

IN-CLASS PROBLEM

Beginning with benzyl bromide, suggest a synthesis of the compound shown below:


CH2 Br

O

CH3

IN-CLASS PROBLEM

Beginning with benzyl bromide, suggest a synthesis of the compound shown below:


2

HO-

O

CH3 H H

O

H

OOH

CH3CH3 H

OHO-

CARBONYL CONDENSATION REACTIONS

The base-catalyzed condensation of two aldehydes or ketones to form a β-hydroxy aldehyde or ketone is known as the Aldol Condensation.


CH3 O

OCH2CH3 O

OO

CH3CH2CH3

O

OCH2CH3

O

CH3OCH3CH2

2

O

CH3OCH3CH2

O

OCH2CH3

+ CH3CH2O-

CH3CH2O-


The base-catalyzed condensation of two moles of an ester is called the Claisen Condensation.

CH3 O

OCH2CH3 O

OO

CH3CH2CH3

O

OCH2CH3

O

CH3OCH3CH2

2

O

CH3OCH3CH2

O

OCH2CH3

+ CH3CH2O-

EtO -

CH3 CH

2 OH

O

H

O

OCH

2 CH3

EtO -/EtOH

CH3

O

HCH O

CH2 CH

3O

O

HCH

3 CH2 O

OH

OCH

2 CH3

OO

CH3 CH

2 OH

H


CH3O-

+ CH3O-

OCH3

O

O

OCH3

OCH3

O

O

OCH3

O O

OCH3

O O

OCH3

CH3O


An intramolecular Claisen is called the Dieckman Condensation.

+ CH3O-

OCH3

O

O

OCH3

OCH3

O

O

OCH3

O O

OCH3

O O

OCH3

CH3O

+ CH3O-

OCH3

O

O

OCH3

OCH3

O

O

OCH3

O O

OCH3

O O

OCH3

CH3O

EtO -

CH3 CH

2 O

H

O

HO

OCH2 CH

3

EtO -/E

tOH

CH3

OH

CHOCH2 CH

3

O

O

H

CH3 CH

2 O

OH

OCH2 CH

3

O

O

CH3 CH

2 O

H

H


O

O

O

Nuc

O

δ

NucO

δ

δ

H+

O

Nuc

O

O

O

Nuc

O

δ

NucO

δ

δ

H+

O

Nuc

REACTIONS OF α,β-UNSATURATED CARBONYLS

Conjugated ketones and aldehydes can undergo an

analogous reaction in which a nucleophile adds to the terminal

carbon of the double bond.

The Michael Reaction of α,β-unsaturated ketones and aldehydes.

αβ


CH3O OCH3

O O

CH3 OCH3

O O

NC CNCH3

OOCH3

OCH3

O

OO

CH3

CH3

ONC

NC

CH3

OO

O

CH3

OCH3

O

(CH3CH2)2AlCN

(CH3)2CuLi

CH3NH2

O O

O

NC

O

CH3

O

NCH3

H

O

(CH3CH2)2AlCN

(CH3)2CuLi

CH3NH2

O O

O

NC

O

CH3

O

NCH3

H

O

(CH3CH2)2AlCN

(CH3)2CuLi

CH3NH2

O O

O

NC

O

CH3

O

NCH3

H


The Michael additions of α,β-unsaturated ketones and aldehydes that we covered include:


CH3O OCH3

O O

CH3 OCH3

O O

NC CNCH3

OOCH3

OCH3

O

OO

CH3

CH3

ONC

NC

CH3

OO

O

CH3

OCH3


Enolate anions also undergo the Michael Reaction:



Michael addition of enamines and nitroalkanes.

CH3 ONO

CH3

O

N

CH3

OO2N

O O

CH3

2. H+/H2O© ChemistryOnline, 2009-2014

CH3

O

2. H+/H2O; heat3. OH-/H2O4. H+/H2O

O

CH3

CH3

O

CH3 OCH3

O O

CH3

OO

O

CH3

OCH3

CH3O-

IN-CLASS PROBLEM

3-Buten-2-one is subjected to the four steps shown below; what will be the major product of this reaction sequence?


OO

O

H

1. HO-

2. H+/H2O

IN-CLASS PROBLEM

Beginning with cyclohexanone, suggest a simple synthesis for the following compound:

OH


O

1. LDA2. CH3CH2Br

O

IN-CLASS PROBLEM



O

CN

1. Br2/CH3COOH2. Pyridine3. (CH3CH2)2AlCN

O

IN-CLASS PROBLEM



H NH

CH3

O

CH3NH2/BH3CN-

IN-CLASS PROBLEM



IN-CLASS PROBLEM

Predict the products for the following reactions:

Br

CO

ClH2N

N- K+

O

O

1.

2. HO-/H2O

+

CH3 SO2Cl

NH2

NH

O

CH3 SO2 NH

NH2

Br

1.


1. NaBH3CN

2. H3O+

O

CH2Br

NH

+

+NH

Cl

O

1. NaN32. heat, H 2O

N

CH2 N

NH2

IN-CLASS PROBLEM



OCH3

O

NH2

CH3NH2

1. CH3NH2 (excess)2. Ag2O, H2O, heat

NH2

ONaOH, Br2, H 2O

NH2

OCH3

O

N

O

H

CH3

IN-CLASS PROBLEM



NH2 N

N

HNO2H2SO4

...a diazonium salt...

FORMATION OF DIAZONIUM SALTS


H3PO2, H 2O

HCl, CuCl

HBr, CuBr

KI

N2

+

REACTIONS OF DIAZONIUM SALTS


KCN, CuCN

H+/H2O

OH

NCH3

CH3

N2

+

REACTIONS OF DIAZONIUM SALTS


C9H10O MW = 134.18

INTEGRATED SPECTROSCOPY: COMPOUND #1

.

m/e30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

Inten

sity

91

65

119

134


INTEGRATED SPECTROSCOPY: COMPOUND #1C9H10O MW = 134.18

.

4000 3000 1500 130020002500 1200 1100 1000 900 800 700

3 4 5 6 7 8 9 10 11 12 13 14 15

Wave Number, cm -1

Wavelength, microns

Abso

rban

ce

3400 cm-1 : 3100 cm-1 : 2900 cm-1 : 2750 cm-1 : 1710 cm-1 : 1610 cm-1 :


INTEGRATED SPECTROSCOPY: COMPOUND #1C9H10O MW = 134.18

ppm, δ7 6 5 4 3 2 1 0

2 2

3

3

13C Spectral Data:

singlet, 196.5 ppmsinglet, 142.1 ppmsinglet, 134.4 ppmdoublet, 129.1 ppmdoublet, 128.5 ppmquartet, 22.8 ppmquartet, 20.9 ppm


C5H9O2Br MW = 181.03

INTEGRATED SPECTROSCOPY: COMPOUND #2

m/e30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

Inten

sity

180-182135-137

107-110


3400 cm-1 :3100 cm-1 :2900 cm-1 :2200 cm-1 :1710 cm-1 :1610 cm-1 :

INTEGRATED SPECTROSCOPY: COMPOUND #2C5H9O2Br MW = 181.03

.

4000 3000 1500 130020002500 1200 1100 1000 900 800 700

3 4 5 6 7 8 9 10 11 12 13 14 15

Wave Number, cm -1

Wavelength, microns

Abso

rban

ce


INTEGRATED SPECTROSCOPY: COMPOUND #2C5H9O2Br MW = 181.03

1

ppm, δ7 6 5 4 3 2 1 0

3

2

31 3C Spectral Data:

singlet, 172.0 ppm;triplet, 59.5 ppm;doublet, 57.7 ppm;quartet, 20.4 ppm;quartet, 13.6 ppm

235 – organic ii eactions onjugated ienes · 1 suggest a synthesis for each of the compounds...

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