structures

Problem 129

3295

IR Spectrum

(liquid film)

4000

3000

2000

1600

1200

800

0.0

V (ern")

100

91

Mass Spectrum

0.5

Q)

o

80

co

\.

III

C1l

UV spectrum

""Q)

-e

60

a.

0

Q)

'"

0.766 mg 110 mls

C1l

134

C1l

..'"Q

1.0

path length: 2.00 cm

40

a

solvent: methanol

20

oR.

M+"

C1QH1sN

II ,Il

,I, ,1",1

I.

u

.l,

149

1.5

40

80

120

160

200

240

280

200

250

300

350

m/e

A. (nm)

I

I

I

I

I

I

I

I

I

I

I

I

13C NMR Spectrum

. ,

ili~

. ~. ".L~

(20.0 MHz, COCI3 solution)

off-resonance decoupled

expansion x10

TMS

proton decoupled

solvent

11

I

I

I

I

I

I

I

I

I

I

I

I

I

200

160

120

80

40

o

0 (ppm)

1H NMR Spectrum

(100 MHz, COCI3 solution)

exchanges

with 0 20

•

TMS

septet

o

10

9

8

7

6

5

4

3

2

1

o(ppm)

218

Chapter 9.3 Problems in 20 NMR

Problem 294

The lH and l3C NMR spectra ofisobutanol (2-methyl-l-propanol, C4H IOO) recorded in CDCh solution at 298K are given below. The IH spectrum contains signals at

83.28 (HI), 2.98 (OH), 1.68 (H2) and 0.83 (H3) ppm. The l3C spectrum contains signals at 869.3 (CI), 30.7 (C2) and 18.7 (C3) ppm. On the facing page produce a schematic diagram of the COSY the C-H correlation spectra for this molecule showing where all of the cross peaks and diagonal peaks would be.

/

isobutanol

1H NMR Spectrum

(300 MHz, CDCJ 3 solution)

~pa",;o,

I

+

3.4

3:2 ppm

expa~jl

Exchanges

with D20 1.8 1.6 ppm

I	I	I	I	•
4.0	3.0	2.0	1.0	ppm

13C NMR Spectrum

(75 MHz; CDCI3 solution)

solvent m

I	I	I	I	I
80	60	40	20	o ppm

388	I
	I

Chapter 9.3 Problems in 20 NMR

u

.111.

j.

ppm

1H - 1H COSY Spectrum

I

I

(300 MHz, CDCI 3 solution)

I

!

,

I

,

I

I

I

------------!-._--!--------------------!------------!---------

I

I

I

I

I

I

1.0

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

,

"

I

I

I

I

I

I

I

___________ .I_.

I

I

I

_

L

L

I

I

I

I

I

I

I

t

I

,

I

2.0

I

I

I

I

,

,

I

I

I

I

I

I

I

I

I

I

-

I

I

i

j

I

I

I

\

I

I

I

I

I

I

I

I

I

I

I

I

f-- --- - -- -_.- --!---- -~----- - --------- --- --!--- - - --- ----!- --- -----

3.0

I

t

I

I

I

I

l,

I

I

_

___________.'-.

l,

i

I

t

I

f

i

I

7

I

I

-

I

I

,

I

I

I

I

I

I

I

I

I

I

:

l-t

4.0

3.0

2.0

1.0

ppm

U

.dl.

j

ppm

C-H Correlation Spectrum

(1 H

300 MHz, 13C 75 MHz; CDCI 3 solution)

I

I

------------

i-----

j ----------------------

~--------------

:----------

20

•

t

i

.

J

l

I

I

I

I

-----------

:-----

1 --------------------

1 ------------

!----------

,

,

I

I

I

I

I

40

I

:

~

!

I

I

I

I

:

I

I

60

i

i

I

r

I

-----------

r-- ---

1----

- --- -- - --

- -- --

i----------

.

:,

:I

:I '

:I

80

I

I

3.0

2.0

1.0

ppm

389

Chapter 9.3 Problems in 20 NMR

Problem 295

The lH spectrum of3-heptanone (C7H I40) recorded in C6D6 solution at 298K at

500 MHz is given below. The1H spectrum has signals at (50.79,0.91, 1.14, 1.44, 1.94 and 1.97 (partly overlapped) ppm. The 2-dimensional lH)H COSY spectrum is given on the facing page. From the COSY spectrum, assign the proton spectrum

i.e. determine the chemical shift corresponding to each of the protons in the molecule.

2

3

4

5

6

7

3-heptanone

v

\

	/
,.	r		I	I	I	I
(	2.4		2.0	1.6	1.2	0.8	ppm

Proton

Chemical Shift (0) in ppm

	H1
	H2
	,,:;;\n>,.',;;:,......... ~;..•...fiJD'	'5;i,;;~		.·!iJ,~;."'!i}~;
			; ~K;.\.:'c. .;';;;.;;;.!,;	"'
		··d'.'·			;" ;-F;";;; ..,
	H4
	H5
	H6
	H7

\

390

Chapter 9.3 Problems in 20 NMR

IH COSY spectrum of3-heptanone (recorded in C6D6 solution at 298K, at 500 MHz).

2

3

4

5

6

7

391

Chapter 9.3 Problems in 20 NMR

Problem 296

The IH and l3C NMR spectra of 8-valerolactone (CSHg02) are given below recorded in C6D6 solution at 298K, at 600 MHz. The IH spectrum has signals at 8 1.08, 1.16,2.08, and 3.71 ppm. The l3C spectrum has signals at 819.0,22.2,29.9,68.8 and 170.0 ppm. The 2-dimensional IH_1H COSY spectrum and the C-H correlation spectrum are given on the facing page. From the COSY spectrum, assign the proton spectrum and use this information to assign the l3C spectrum.

3

o-valerolactone

:0;

a a

,

\		1H NMR Spectrum
		(600 MHz, c.o, solution)			,---
	, . ---
				~			-
								\J
	I	I	I		I	I			I
	3.5	3.0	2.5	2.0		1.5	1.0			ppm

solvent

	13 C NMR Spectrum	+
	(150 MHz, CeDe solution)
/
/		I
I

J

180

160

140

120

100

80

60

40

20

ppm

Proton

Chemical Shift (0) in ppm

Carbon

Chemical Shift (8) in ppm

C) ••••

0'

"',); .,,; :ic:~',:;

C1

Ir?i:i iii

,c,:, ,i{ii"

i'c:~ c,':

. "':,'

H2

C2

H3

C3

H4

C4

HS

CS

392

Chapter 9.3 Problems in 20 NMR

1H -1H COSY Spectrum

(600 MHz, Benzene-Dg solution)

+	1.0

2.0

1-

3.0

40

60

4.0	3.0	2.0	1.0	ppm

393

Chapter 9.3 Problems in 20 NMR

Problem 297

The IH and BC NMR spectra of l-bromobutane (C4H9Br) are given below. The IH spectrum has signals at 8 0.91, 1.45, 1.82, and 3.39 ppm. The BC spectrum has signals at 813.2,21.4,33.4 and 34.7 ppm. The 2-dimensional 1H)H COSY spectrum and the C-H correlation spectrum are given on the facing page. From the COSY spectrum, deduce the assignment of the proton spectrum and use this information to assign the B C spectrum.

		4		3	2
1-bromobutane
Proton		Chemical Shift (8)		Carbon		Chemical Shift (8)
		in ppm				in ppm
H1				C1
H2				C2
H3		.		C3
H4				C4
lH NMR Spectrum
(400 MHz, CDCI, solution)

I		iii	i	i
3.4 ppm		1.8 1.6 1.4	1.2	t.e ppm

/I,.........~~,.........~~,.,.....,~~,..,...,-~~,..,...,-~~,..,...,-~~,..,...,-~~,......~~.,--r~~.,--r~~.,--r~

(	i	9	8	7	6	5	4	3	2	ppm

13C NMR Spectrum

(100 MHz, CDCI, solution)

DEPT CH,. CH,t CHt

proton decoupled

•

I

120	80	40	o	ppm

394

3.0

-- I

			3.0	2.0	1.0	ppm
		4.0

395

Chapter 9.4 NMR Spectral Analysis

Problem 326

A 200 MHz 'H NMR spectrum of a 5-proton system is given below.

(a)Draw a splitting diagram.

(b)Analyse this spectrum by first-order methods, i.e. extract all relevant coupling constants (J in Hz) and chemical shifts (0 in ppm) by direct measurement.

. (c) Justify the use of first-order analysis (see Section 5.6).

		2H			2H		1H
					I		I
1010		990	510		490		110	90
	Hz from TMS				Hz from TMS		Hz from TMS

437