CHEM Spectroscopy and Separations

Question 1

Infrared Spectroscopy

Answer 1

For Functional Groups

Uses radiation w/ a frequency lower than that of visible light to vibrate covalent bonds (must have dipole moment)

Question 2

1550 - 1650 wavenumber (cm-1)

Answer 2

C=N

Question 3

1600 - 1680 wavenumber (cm-1)

Answer 3

C=C

Question 4

1650 - 1780 wavenumber (cm-1)

~1700

Answer 4

C=O

Sharp

Question 5

2100 - 2260 wavenumber (cm-1)

Answer 5

C≡C

Question 6

2220 - 2260 wavenumber (cm-1)

Answer 6

C≡N

Question 7

3200 - 3600 wavenumber (cm-1)

Answer 7

O-H

Broad

Question 8

3300 - 3500 wavenumber (cm-1)

Answer 8

N-H

Question 9

Area below 1500 wavenumber (cm-1)

Answer 9

Fingerprint region

Question 10

NMR Spectroscropy

Nuclear Magnetic Resonance

Answer 10

Characterizes a molecule’s atoms

Question 11

Left side of NMR

Answer 11

Downfield = DEshielded = close to e- withdrawing groups

Question 12

Right side of NMR

Answer 12

Upfield = shielded = far from e- withdrawing groups

Question 13

1-HNMR (proton NMR) area under peak

Answer 13

Corresponds to # of equivalent hydrogens

Question 14

Splitting

Answer 14

N + 1 Rule
Singlet, doublet, triplet, etc.
is determined by # of hydrogens on adjacent atom

Question 15

0.9 ppm shift

Answer 15

-CH3

Question 16

1.0 - 5.5 ppm shift

Answer 16

-CH2OH

Question 17

2.0 - 3.0 ppm shift

Answer 17

-C≡CH

Question 18

4.5 - 6.0 ppm shift

Answer 18

-CH=CH-

Question 19

6.0 - 8.4 ppm shift

Answer 19

Ar (aromatic ring) - H

Question 20

9.5 ppm shift

Answer 20

-CHO

Question 21

10.5 - 12.0 ppm shift

Answer 21

-COOH

Question 22

N+1 rule

Answer 22

For splitting patterns of 1-HNMR

Any peak will be split into a number of smaller peaks equal to the number of adjacent hydrogen atoms plus one

Question 23

13-CNMR

Answer 23

Most carbon on earth is in 12-C form but 13-C is used because only nuclei with an odd number of proteins have nuclear spin

Ranges from 0 - 200 ppm

Just like 1-HNMR but looking at Carbons

Question 24

UV-Visible Spec

Answer 24

Useful o discern presence of conjugated/aromatic species

Question 25

Mass Spec

Answer 25

Helps determine molecular weight (m/z peak; mass to charge ratio peak) of organic compounds

Question 26

Distillation

Answer 26

Separates liquids based on Boiling Points

Question 27

Simple Distillation

Answer 27

used for BPs > 25˚ apart

Question 28

Fractional Distillation

Answer 28

used for BPs < 25˚ apart

Question 29

Vacuum Distillation

Answer 29

used for very high BPs | used to lower atmospheric pressures in order to lower BPs

Question 30

Extraction

Answer 30

Separates liquids based on solubility/acid-base properties

Question 31

Extraction Requires

Answer 31

Immiscible aqueous and organic layers in a sparatory funnel

Question 32

Extraction: to send an ACID into aqueous layer...

Answer 32

Add base (deprotonate it)

Question 33

Extraction: to send a BASE into aqueous layer..

Answer 33

Add acid (protonate it)

Question 34

Chromatogrpahy

Answer 34

Involves a mobile phase and a stationary phase with different properties

Question 35

TLC (thin-layer)

Answer 35

Rough measure of polarity Stationary phase = polar silica Mobile phase = nonpolar solvent Rf = distance traveled by compound / distance traveled by solvent

Question 36

Forms of Column Chromatography

Answer 36

Stationary phase = in column Different analyts will be eluted out at different times and can be collected in separate containers ``` Size-exclusion Cation-exchange Anion-exchange Affinity Gas HPLC ```

Question 37

Gas Chromatography (GC)

Answer 37

Vaporizes a sample and passes through a column, then measures retention time Stationary phase = liquid Mobile phase = gaseous (like He)

Question 38

HPLC (high performance or high pressure liquid chrom)

Answer 38

Rapid method of column chromatography Stationary phase = polar Mobile phase = nonpolar

Question 39

RP-HPLC (reverse process)

Answer 39

Stationary phase = NONpolar | Mobile phase = polar

Question 40

Other seperation techniques

Answer 40

Recrystallization | Filtration

Question 41

Paper Chromatography

Answer 41

Mobile phase moves up filter paper via capillary action

Question 42

Size-Exclusion Chromatogrpahy

Answer 42

Gel beads contain pores and act as molecular sieve that catches up small particles, making them elue more slowly

Question 43

Ion-Exchange Chrom

Answer 43

Relies on charge interactions

Question 44

Anion-exchange Chrom

Answer 44

Gel contains cations that trap anions | Anions elute last

Question 45

Cation-exchange Chrom

Answer 45

Gel contains anions that trap cations | Cations elute last

Question 46

Affinity Chrom

Answer 46

More specific interactions | Ex: Antibody-Antigen

Question 47

Electrophoresis

Answer 47

A charge is applied across a gel and molecules migrate due to the applied voltages

Question 48

Gel Electrophoresis

Answer 48

Also affected by size due to gel filtration properties

Question 49

SDS-PAGE

Answer 49

This allows proteins to be separated by mass alone SDS and anionic detergent that results in an even distribution of charge per unit mass

Question 50

Isoelectric focusing

Answer 50

Uses electrophoresis with a pH gradient to separate proteins by the pI (isoelectric point; the pH where a protein has a net zero charge = zwitterion)

Question 51

Western blotting

Answer 51

After electrophoresis, an antibody specific to the separated protein of interest is applied and visualized

Question 52

Enzyme-linked Immunosorbent Assay (ELIZA)

Answer 52

Specific visualizable detection antibodies are used to find antigens