Spectroscopy and organic synthesis

Question 1

What can be used to identify the presence of certain bonds?

Answer 1

Infra red absorptions, as it causes covalent bonds to vibrate at characteristic frequencies

Question 2

What wavenumber does O-H bond in alcohols appear?

Answer 2

3200-3600, it’s a steep drop

Question 3

What wavenumber does O-H bonds in carboxylic acids appear?

Answer 3

2500-3300, broad drop

Question 4

What wavenumber does C-H bonds appear?

Answer 4

2850-3100, lots of little drops

Question 5

What wavenumber does C=O bonds appear, in aldehydes, ketones, carboxylic acids, esters?

Answer 5

1630-1820, very steep drop

Question 6

What’s the fingerprint area?

Answer 6

Bellow 1500, ignore it

Question 7

2 other uses of infra red spectroscopy?

Answer 7

Checking breathing sample for alcohol presence

Monitoring air pollution

Question 8

Greenhouse effect definition?

Answer 8

Warming of the atmosphere due to the trapping of IR, by absorption by molecular bonds

Question 9

What are the 3 most important greenhouse gasses?

Answer 9

H2O, CO2, CH4

Question 10

On a molecular level, how do greenhouse gasses trap heat close to the Earth’s surface?

Answer 10

Heat (IR), is released from planets surface
IR is then absorbed by the molecular bonds which vibrate.
The IR (heat) is then re-released
Some will continue to space, but some is reflected back to the surface keeping it warm

Question 11

What 2 factors determine a gas’s contribution to global warming?

Answer 11

Energy absorbed by the bonds

The concentration / amount of absorbing molecules in the atmostphere

Question 12

Why can the term “global warming” be misleading?

Answer 12

Although the Earth will have higher temperatures on average, some areas will actually experience cooling effect

Question 13

Consequences of global warming?

Answer 13

Climate change
Loss of drinking water
Mass migration
Flooding due to rising sea levels
Loss of wildlife habitat
Increased incidences of extreme weather

Question 14

Ways to combat excessive greenhouse gases and consequences?

Answer 14

Increased use of renewable resources

More efficient energy used

Question 15

3 key pieces of information a mass spectrum can tell you about isotopes?

Answer 15

Number of isotopes
The relative mass of each isotope
The relative abundance of each isotope

Question 16

How does the M+1 peak occur?

Answer 16

When a molecular ion is created with an isotope of C 13 instead of C12, so the more carbon atoms the higher the M+1 peak (100:1.1 ratio)

Question 17

How is the full molecular ion created?

Answer 17

Hit with e- missile, knocks electron of creating molecular ion with positive charge

Question 18

What’s fragmentation?

Answer 18

Where the collision with missile leaves molecular ion with a lot of energy, causing a covalent bond to break

So creates positively charged molecular ion which is detected and an uncharged particle which isn’t detected