Chemistry 328N

Lecture 5

Still More nmr

February 2, 2016

three spins

Chemistry 328N

You don’t need DNA

to tell these apart!!

Chemistry 328N

Splitting of Signals

Nonequivalent protons split each other if they are on

adjacent carbons, i.e. separated by 3 sigma bonds

Chemistry 328N

Splitting of Signals

Equivalent protons never split each other

Chemistry 328N

Outside the ring

the induced field

helps big magnet

Chemistry 328N

BUT……………….

When using the Right-Hand Rules, it is important to remember

that the rules assume charges move in a conventional current

(the hypthetical flow of positive charges). In order to apply the

Right-Hand Rule to a moving negative charge, the direction of

charge flow must be reversed--….or use your LEFT hand.

The Right-Hand Rule #2

determines the direction of the

magnetic field aroud a current-

carrying wire and vice-versa

Chemistry 328N

“Tricks” for solving unknowns

Review….

Empirical formula is lowest common

denominator ratio of atomic composition

From Homework: unknown has an empirical

formula of C4H9….a single high field peak in

the 1H nmr and a molecular ion at M/Z = 114.

….propose a structure..and predict the M/Z of

the most intense fragment you expect to see in

the mass spectrum

Chemistry 328N

Index of Hydrogen Deficiency

I knew this as the unsaturation number

Valuable characteristic of structure

– Provides you with number of double bonds or rings

in a compound

– Easy with CHO formulas only…be careful with N

– Simplest, “saturated” normal alkanes have:

H –(CH2)n–H = CnH2n+2

Chemistry 328N

Index of H Deficiency

IHD: the sum of the number of rings and pi

bonds in a molecule….

Compare the number of hydrogens in an

unknown compound with the number in the

reference compound CnH2n+2

Chemistry 328N

CnH2n+2

C6H14

C6H12

2/2=1 => 1 ring or 1 double bond

Index of H Deficiency

IDH =2

(Hreference - Hmolecule )

C6H12 C5H10 C9H14

-

Chemistry 328N

Index of H Deficiency

No correction is necessary for the addition of

atoms of O

Subtract one H for each atom of halogen added

(halogens like Cl replace H one for one)

Add one hydrogen For each atom of N added to

the reference hydrocarbon

IDH =2

(Hreference - Hmolecule )

Chemistry 328N

“Unsaturation” Number or HDI

Should be CnH2n+2 +1-1 = C8H18

but it is… C8H14

Missing H4

So index is…. 4/2=2

Add one H for N and

subtract one for ClN

Cl H

CH3

C8H14ClN

Chemistry 328N

Calculate the Unsaturation Number

Should be CnH2n+2 +1 = C8H19

but it is… C8H9

Missing H10

So number is…. 10/2=5!

Add one H for NN

HH

H C8H9N

Chemistry 328N

An Unknown

C5H10O

9 8 7 6 5 4 3 2 1 00

1

2

3

4

5

6

7

8

9

10

11

12

13

Chemistry 328N

0

Type of H d

1.6-2.6

2.0-3.0

0.9

1.2-1.4

1.4-1.7

2.1-2.3

0.5-6.0

2.2-2.6

3.3-4.0

2.2-2.5

0.5-5.0

RC CH

O

O

RCH2 OR

(C H3 ) 4 Si

ArC H3

RCH3

RCCH3

ROH

RCH2 R

R3 CH

R2 NH

RCCH2 R

R2 C=CRC HR2

Type of H d

Chemical Shift - 1H-NMR

Chemistry 328N

Chemical Shift - 1H-NMR

4.6-5.0

9.5-10.1

5.0-5.7

10-13

3.5-3.9

4.1-4.7

3.1-3.3

3.4-3.6

3.6-3.8

4.4-4.5

6.5-8.5

O

O

O

O

R2 C=C HR

RCH

RCOH

RCH2 Cl

RCH2 Br

RCH2 I

RCH2 F

ArH

R2 C=C H2RCOC H3

RCOC H2 R

Type of H d Type of H d

Chemistry 328N

Sample spectra

2.50 2.40 2.30 2.20 2.10 2.00 1.90 1.80 1.70 1.60 1.50 1.40 1.30 1.20 1.10 1.00 0.900

5

10

15

4

6

18

CH3

CH3

CH3CH3

O

C7H14O

Chemistry 328N

CH3CH2CH2NO2

Chemistry 328N

Multiple interactions of non-equivalent neighbors here Jab > Jbc

Chemistry 328N

ClCH2CH2CH2Cl

3.5 3.0 2.50

1

2

3

4

5

6

7

8

9

2.30 2.20 2.100.0

0.5

1.0

1.5

2.0

2.5

3.0

Chemistry 328N

5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.00

1

2

3

4

5

6

7

5.80 5.70 5.600.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

1.20

2.20 2.10 2.000.0

0.5

1.0

1.5

2.0

1.20 1.10 1.000.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5Cl2HCCH2CH3

Chemistry 328N

An analysis

2.20 2.10 2.000.0

0.5

1.0

1.5

2.0

Chemistry 328N

More Practice

4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.00

5

10

15

1.50 1.40 1.30 1.20 1.10 1.000

1

2

3

4

5

6

7

8

9

10

4.5 4.0 3.50.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5 C6H14O2

Chemistry 328N

0

Type of H d

1.6-2.6

2.0-3.0

0.9

1.2-1.4

1.4-1.7

2.1-2.3

0.5-6.0

2.2-2.6

3.3-4.0

2.2-2.5

2.3-2.8

0.5-5.0

RC CH

O

O

RCH2 OR

(C H3 ) 4 Si

ArC H3

RCH3

RCCH3

ROH

ArC H2 R

RCH2 R

R3 CH

R2 NH

RCCH2 R

R2 C=CRC HR2

Type of H d

Chemical Shift - 1H-NMR

Chemistry 328N

4.6-5.0

9.5-10.1

5.0-5.7

10-13

3.5-3.9

4.1-4.7

3.1-3.3

3.4-3.6

3.6-3.8

4.4-4.5

6.5-8.5

O

O

O

O

R2 C=C HR

RCH

RCOH

RCH2 Cl

RCH2 Br

RCH2 I

RCH2 F

ArH

R2 C=C H2RCOC H3

RCOC H2 R

Type of H d Type of H d

Chemical Shift - 1H-NMR

Chemistry 328N

Deuterium Oxide

Heavy water is heavier than H2O (duh?), having a density of 1.108 g/cm3. Heavy water ice will actually sink in light liquid water. The freezing and boiling points are also elevated somewhat, with heavy water freezing at 3.81° C (38.86° F) and boiling at 101.42° C (214.56° F) at standard atmospheric pressure.

Heavy water toxicity manifests itself when about 50% of the water in the body has been replaced by D2O. Prolonged heavy water consumption can cause death. The price is about $300 per kilogram.

Chemistry 328N

D2O in H2O

D2O ice in H2O D2O ice in D2O

Chemistry 328N

Property D2O (Heavy water) H2O (Light water)

Freezing point (°C) 3.82 0.0

Boiling point (°C) 101.4 100.0

Density at STP

(g/mL)1.1056 0.9982

Dynamic viscosity (at

20°C, mPa·s)1.25 1.005

Heat of fusion

(cal/mol)1,515 1,436

pH (at 25°C) 7.41 (sometimes "pD") 7.00

Cost per kilogram ~$300~$0.002 for tap

~$5.00 for Fiji!!?

Deuterium Oxide vs Water

Chemistry 328N

http://www.imdb.com/

title/tt0059263/

Joachim Ronneberg

Heavy water plant in

Vemork, Norway

http://www.telegraph.co.uk/news/7664351/A-new-mission-

for-the-hero-of-Telemark.html

Chemistry 328N

Vemork Hydroelectric Plant