CHEMISTRY 251 — Spectroscopy Problems

The IR below is most likely of a:

alkane alkene

alkyne

aldehyde

alkyl bromide

The IR below is most likely of a:

acyl chloride alcohol 3° amide

ether nitrile

The IR spectrum below is most likely of:

CH3

CH3

O

CH3

CH3

OH

O CH3

CH3

CH3

CH3

NH2CH3

CH3

The IR spectrum below is most likely of:

CCO2EtCO2HNH2 N

NH2

O

The IR below is most likely of a:

NH2OMe

NH2CO2Me

NN

H

ONH2

CN

The IR below is most likely of a:

NH2OMe

NH2CO2Me

NN

H

ONH2

CN

The IR below is most likely of a:

O

O

O

O O

OH

O

O C N

The IR spectrum below is most likely of:

OH

O

O

OHO

O

O

CH2CHCH2

CH3(CH2)14CO2CH3(CH2)14CO2

CH3(CH2)14CO2

CH3

CH3

CH3

CH3 CH3CHO

CH3

CH3

CH3

CH3

H3CCHO

The IR spectrum below is most likely of:

CH3C CH3

O OH

CH3

N

HO

CH2CH3

H3C CH3

CH3 CH3

CH3

CH3

CH3H3CC

OCH2CH3

ON

The mass spectrum below is most likely of:

Note: The atomic mass of C is 12, the atomic mass of H is 1, the atomic mass of N is 14, & the atomic mass of O is 16. Br exists as ~50% 79Br and 50% 81Br. Cl exists as ~75% 35Cl and 25% 37Cl.

acyl bromide alkyl chloride

alcohol amine ether

The mass spectrum below is most likely of:

alkyl bromide acyl chloride

alcohol amine ether

The mass spectrum below is most likely of:

alkyl bromide acyl chloride

alcohol amine ether

The mass spectrum below is most likely of:

CH3–CH2–O–CH3CH3–CH2–CH2–OH CH3–CH2–CH2–NH2HC–CH2–OH

O

ClH

The mass spectrum below is most likely of:

Br

N

CH3

O OCH3

OHO

Cl

O CO2H

Earlier, you learned that alkynes could be converted to alkanes via hydrogenation (Scheme 1). Were you to run such a reaction in the lab, how could you use IR to determine when the reaction was done?

Scheme 1

Take IR spectra of the reaction at regular time points. In this way monitor the disappearance of the alkyne stretch at 2100–2260 cm-1. When it's gone the reaction is done.

H2

Pt/CHCH3OCH2CH2CH2 CH3OCH2CH2CH2CH2CH3

(a) Describe how one would use IR to distinguish between the two amine isomers shown below

The IR spectrum of B will have an stretch at 3300–3500 cm-1. That region will be clear of any peaks for A.

(b) Describe how one would use mass spec to distinguish between the two amine isomers shown below (5 pts).

CH3CH2CH2N

CH2CH3

CH3

A

CH3CH2CH2CH2CH2N

H

CH3

B

CH3CH2CH2N

CH2CH3

CH3

A

CH3CH2CH2CH2CH2N

H

CH3

B

CH3CH2—CH2N

CH2—CH3

CH3

A

CH3CH2CH2CH2—CH2N

H

CH3

B

!-cleavage 1

H2CN

CH—CH3

CH3

CH3CH2• +

[M — 29]

!-cleavage 2

CH3CH2—CH2N

CH2

CH3

+ •CH3

[M — 15]

!-cleavage

H2CN

CH—CH3

CH3

CH3CH2CH2• +

[M — 43]

parent peakd for both A & B m/z 101

A. List in tabular form the expected signals for the proton NMR spectrum of E and then sketch that spectrum. proton(s) relative chemical shift (ppm) multiplicity integration

~3.8 ppm p 1

~2.8 ppm d 2

~2.1 ppm s 3

~1.2 ppm d 3

Cl O

H

Cl O

H H

CH3

Cl O

H3C

Cl O

1

2

3

TMS

0 ppm

12345678

3

E

C

O

C

H

C

H

H3C CH3

H

Cl

List in tabular form the expected signals for the proton NMR spectrum of D and then sketch that spectrum.

proton(s) relative chemical shift (ppm) multiplicity integration

~7.2 ppm m 5

~3.9 ppm t 2

~3.2 ppm s 3

~2.2 ppm t 2

~1.3 ppm t 2

O

H H

H

HH

C

H

O

H

OC

H

H

H

C

H

H

O

CC

H

H

C

H

H H

H

O

H H

H

HH

TMS

0 ppm

12345678

53

2

OC

H

H

H

C

H

O

H

2 2

C

H

H

O

CC

H

H

C

H

H H

H

CCH

OH

C CH

H H

H

O

H H

H

HHH

HH

D

List in tabular form the expected signals for the proton NMR spectrum of D and then sketch that spectrum proton(s) relative chemical shift (ppm) multiplicity integration

~7.2 ppm m 5 t-Butyl group 0 – 2 ppm s 9 –CH2–Ph 2 – 3 ppm t 2 O–CH2– 3 – 4 ppm t 2

H H

H

HH

H H

H

HH

TMS

0 ppm

12345678

5

9

t-Bu

O–CH2– –CH2–Ph

2 2

CH2

H H

H

HHD

CH2OC

CH3H3C

CH3

List in tabular form the expected signals for the proton NMR spectrum of A and then sketch that spectrum.

proton(s) relative chemical shift (ppm) multiplicity integration ~7.2 ppm m 5

~6.9 ppm d 1

~6.2 ppm d 1

~4.2 ppm s 2

~3.5 ppm q 1

~1.4 ppm d 3

~1.0 ppm s 6

O

O BrH

O

O Br

H

O

O BrH H

O

O Br H

O CH3

O Br

O

O

H3C CH3

Br

HH

H

HH

TMS

0 ppm

12345678

5 6

1 1 1

2

3

A

O CH3

OH H H

H3C CH3

H Br

H

H

H

H

H

H

H

H

H

H

H

The 1H-NMR spectrum below is most likely of:

Note: The proton NMR data (including the relative integration) are as follows: the triplet at 3.4 ppm (2H), the multiplet at 1.6 ppm (2H), and the triplet at 0.9 ppm (3H).

ClO CH3

O

H3C Cl

OO OO

H N CH3

O

CH3

O

H3C CH3

The 1H-NMR spectrum below is most likely of:

Note: The proton NMR data (including the relative integration) are as follows: the doublet at 7.83 ppm (1H), the overlapping series peaks from 7.20-7.63 ppm (3H), the quartet at 2.90 ppm (2H), and the triplet at 1.27 ppm (3H).

CH2CH3

NO2

CH2CH2NO2CH2OCH3

NO2

CH2CH3

NO2

CH2CH3

NO2

CH2CH3

NO2

The 1H-NMR spectrum below is most likely of:

Note: The proton NMR data (including the relative integration) are as follows: the broad singlet at 11.42 ppm (1H), and the singlet at 2.10 ppm (3H).

H3C OH

O

F3C OH

O

C H

O

H3C

H3C

CH3HO

H3C

O

CH3H3C

CH3

The 1H-NMR spectrum below is most likely of:

Note: The proton NMR data (including the relative integration) are as follows: the doublet at 7.97 ppm (2H), the doublet at 6.89 ppm (2H), the singlet at 3.86 ppm (3H), and the singlet at 3.82 ppm (3H).

CO2Me

MeO

CO2Me

MeMe

O

Me

MeO

O

Me

OMe

MeO

The 1H-NMR spectrum below is most likely of:

Note: The proton NMR data (including the relative integration) are as follows: the multiplet at 7.25 ppm (2H), and the singlet at 2.40 ppm (3H).

Me

Me

OMe

F

FF

CH3–CH2–BrH CH3

CH3HMe CH2OH

The 1H-NMR spectrum below is most likely of:

Note: The proton NMR data (including the relative integration) are as follows: the broad singlet at 3.78 ppm (1H), the triplet at 3.67 ppm (2H), the triplet at 3.57 ppm (2H), and the pentet at 1.90 ppm (2H).

Cl OH Cl CHOClCl Cl OHClO

The 1H-NMR spectrum below is most likely of:

Note: The proton NMR data (including the relative integration) are as follows: the multiplet at 2.58 ppm (1H), the quartet at 2.45 ppm (2H), the doublet at 1.07 ppm (6H), and the triplet at 1.01 ppm (3H).

O

O

OO

O

O

O O

O

The 1H-NMR spectrum below is most likely of:

O

O

H3C CH3CO

O CF3CO

CH3—O—CH2—O—CH3 CF3C

O

The 1H-NMR spectrum below is most likely of:

integration: 1 2 2 2 3

OO

OCHOO

O O

The 1H-NMR spectrum below is most likely of:

integration: 1 1 3 3

MeMe

OH

MeMe

O

OHMe

Me

O

OMeMe

Me

O

HMe

Me

OMe

The IR and proton NMR of compound D are provided below.

The mass spec of D provides a molecular formula of C5H10O2. Major mass spec fragment peaks are also observed at m/z = 43, 60, and 73. What is the structure of compound D?

Note: The proton NMR data is a follows: 4.1 ppm (triplet, 2H), 2.1 ppm (singlet, 3H), 1.7 ppm (multiplet, 2H), and 0.9 ppm (triplet, 3H).

D

H3C C CCH2CH2CH3

O

The IR and proton NMR of compound E are provided below. The molecular formula of compound E is C6H12O2. What is the structure of compound E?

Note: The relative integration for the proton NMR is a follows: the quartet at 4.1 ppm (2H), the triplet at 2.2 ppm (2H), the multiplet at 1.7 ppm (2H), and the triplet at 1.3 ppm (3H) and the triplet at 0.9 ppm (3H).

E

O

O

The IR and proton NMR of compound F are provided below. The molecular formula of compound F is C5H10O. What is the structure of compound F?

Note: The relative integration for the proton NMR is a follows: the triplet at 2.4 ppm (2H), the singlet at 2.12 ppm (3H), the multiplet at 1.6 ppm (2H), and the triplet at 0.91 ppm (3H).

C CH

HH C

OC C

H

H

H

H

H

HH

F