Separation Techniques, Spectroscopy, & Analytical Methods

Thin layer chromatography

separation of components of a mixture based on their polarity.

Stationary phase— polar, adsorbent material like silica (SiO2)

Mobile phase- organic solvent that is less polar than stationary and travels up the stationary phase via capillary action

Separation occurs because the mixture component travel up the plate at different rates depedning on strength of competing intermolecular interactions between mixture component and staionary and mobile phases.

Which of the R?

CH3-substituted benzaldehyde, because it forms fewer hydrogen bonds than the OCH3

Checking the density to know which layer is organic and aqueous layer

GC: L1- ethyl acetate 0.901 g/ml . L2— water/ethanol about 1 g/ml

B&D: L1— water/ethanol L2 chloroform 1.489 g/ml

Sterol should be in the organic layer

and so

BD L2 & GC L1

Answer C

Answer: D

0.5/10 = 1/20

0.5/1 = ½
1/20 × ½ = 1/40

so a dilution of 40

Answer B

Answer B

Types of distillation

Simple

Fractional

Vacuum

Vacuum distillation

performed udner reduced system pressure, wchich lwoers a compound’s boiling point

This is ideal for compounds wiht greater than 150ºC BP

Fractional distillation

Simple distillation

1, 4

racemic, enantionmers, diastereomers, conformational isomers?

diasteromers

Answer: 1

Answer A (step 1)

Answer D

a polar mobile phase and nonpolar stationary phase (reverse of normal TLC)

what is the value in m/z?

ANswer D

decrease in pH or increase in pH of sample solvent

specific rotation

IR spectroscopy absorption frequencies

Answer A

it will be different

Answer B

Answer D

A is higher shift

106

high perforance liquid chromatography

1 and 2 only

The anistropy of aromatic ring

LUMO

lowest unoccupied molecular orbital is the lowest energy vacant molecular orbital

HOMO

highest occupied molecular orbital highest energy molecualr orbital containing at least one electron

what does delocalization of electrons do to the energy of filled orbitals? Energy different between homo and lumo?

it decreases the average energy of filled orbitals. Consequently, conjugated alkenes are mreo stable, of lower energy, and have a smlaler energy difference between HOMO and LUMO.

Note the difference in the image of HOMO (blue) and LUMO (yellow), as it gets more conugated

energy difference of HOMO- LUMO is smaller for which compound?

which is ore conjugated and what color does it show up as?

Base peak of mass spectrum

highest relative abundance

The molecular ion of mass spec has…

the highest m/z value

values next to them are isotopes

anatomy of a mass spec

changes in electronic structure cause the solution to change from yellow to blue

or

changes in the mass to charge ratio cause the solution to change form violet to orange

Basically, which one would remain in the reaction flask?

4nitrophenol remains in the flask because it has more INTER molecular hydrogen bonding

mass spec, H NMR spec, TLC with UV light, Gas chromatoraphy

TLC with UV light

Spot B; acetaminophen

functional groups in IR spec infared spec

Let x be original concentration of solution 1 as a placement holder

(solving solution 1 volume) X*(?)= X/20×50

?= 2.5ml

D vs L configuration

answer 1 only

29 or 27%?

29%

2,3,5 or 6?

GL6

Answer B

0.05×1×10^7 correct= 5 ×10^5

1×10² wrong nucleotides = 10² nucleotide

5×10^5/10² =

5000 correct per 1 incorrect

Answer D