Infrared Spectrometry

Question 1

Spectroscopic Analysis Function

Answer 1

Quality control for regulatory bodies and published standards (pharmacopia)

Question 2

Pharmaceutical Impurities Sources

Answer 2

Manufacturing, product degradation, packaging and microbiological contaminants

Question 3

How impurities are separated and analysed

Answer 3

Purified by chromatography. Analysed by spectroscopy and spectrometry

Question 4

How Infrared is perceived to humans

Answer 4

Not visible (wavelength too long), perceived as heat. The greater the heat, the more IR radiated

Question 5

Thermography Def

Answer 5

Measures heat released

Question 6

IR Spectroscopy Def

Answer 6

Qualitative Identification. Identifies functional groups by bond vibrations, characterises solid samples and water content is measured. IR spectra are unique to each functional group

Question 7

UV Spectroscopy

Answer 7

electron transitions determine bonding patterns

Question 8

Nuclear Magnetic Resonance Spectroscopy

Answer 8

Detects H atom signals and distinguishes isomers

Question 9

Melting Point and purity

Answer 9

Melt sample. The narrower the range of temps melted over = the more pure the sample

Question 10

Which C double bond is longer acid or ester

Answer 10

acid

Question 11

Which is longer C double bond or OH

Answer 11

C double bond

Question 12

Relationship between wavelength and frequency

Answer 12

bigger wavelength = smaller frequency

Question 13

How adding energy to bond impacts it

Answer 13

It stretches or changes angle

Question 14

Stretching Def

Answer 14

Changing of bond length. 2 Types

Question 15

Symmetric stretching def

Answer 15

All bonds lengthen and shorten at the same time

Question 16

Asymmetric Stretching def

Answer 16

When half the bonds lengthen the other half shortens

Question 17

Changing of bond angles

Answer 17

Angles changes in relation to body and substituents. 4 Types

Question 18

In plane Outline

Answer 18

Both bonds move left and then right at the same time

Question 19

Scissoring Outline

Answer 19

Bond angle move together at the same time and then apart

Question 20

Out of Plane Wagging

Answer 20

Both bond move closer to main body of molecule and away

Question 21

Out of plane twisting

Answer 21

1 bond moves away from the body of molecule and 1 moves nearer

Question 22

Which is longer stretching or bending

Answer 22

bending frequencies are lower then stretching

Question 23

Which bond angles are longer

Answer 23

rock > scissor > wag

Question 24

Which stretching is longer

Answer 24

Asymmetric > symmetric. Symmetric is lower frequencies then assymetric

Question 25

IR Activity Rules

Answer 25

IR absorption causes bending if there's a change in dipole moment. Thus homonuclear (2 atoms are the same) don't vibrate

Question 26

Linear (no branching) number of fundamental; vibrations

Answer 26

3(no of atoms) - 5

Question 27

Non-linear (branched) no. of fundamental vibrations

Answer 27

3(no of atoms) - 6

Question 28

Water Vibrational Nodes

Answer 28

symmetric (3652 cm^-1), bends (1,595 cm^-1, longer), asymmetric angles (3,756 cm^-1)

Question 29

Deformation Def

Answer 29

The functional groups move away from and towards each other. Umbrella like movement

Question 30

Skeletal Vibrations Range

Answer 30

1400 - 600 cm^-1. This is the fingerprint region

Question 31

Bond strength

Answer 31

triple bond > double bond > single bond

Question 32

Relationship between vibrational frequency (n bar) and mass of 2 atoms (mew bar)

Answer 32

vibrational frequency is inversely proportional to mass

Question 33

Relationship between force constant (strength of bond) (k) and vibrational frequency

Answer 33

As strength of bond increases, vibrational frequency decreases

Question 34

Calculation for bond frequency

Answer 34

v bar = 1/(2(pi)c) x (k/mew)^1/2

Question 35

How do frequencies tend to move across the x-axis

Answer 35

Frequencies decrease movinf feom left to right

Question 36

What influences frequency range (breadth of bands)

Answer 36

Hydrogen Bonding

Question 37

Why might alkene and alkynes be represented in chart

Answer 37

Obscured by other absorbances in region and bands are of bare and medium intensity

Question 38

How do you increase the strength of absorption in alkynes

Answer 38

If they are asymmetric

Question 39

Why are carbonyl bands so broad

Answer 39

Reactive in nucleophilic addition. Ketones, aldehydes and amines are lower. Usually longest signal

Question 40

Steps for analysing IR chart if C double bond O is present

Answer 40

Check OH (carboxylic acid), check NH (amide), check C-O (ester)

Question 41

Steps for analysing IR chart if no C double bond O

Answer 41

Check OH (alcohol), check NH (amine), check C-O (ester), look C double bond (aromatic)

Question 42

Conjugate bonds Def

Answer 42

Molecules with atoms with both single and double bonding

Question 43

Relationship between conjugation and frequency absorption

Answer 43

More conjugation = lower absorption (electrons move from bond to bond). Aromatic is lowest

Question 44

Relationship between electrons in s and p orbitals and frequency absorption

Answer 44

more electrons =absorbs at higher frequency