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CHEM 354 > EXAM 2 (EXP 13, 24, 22, 35, 58) > Flashcards

EXAM 2 (EXP 13, 24, 22, 35, 58) Flashcards

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1
Q

IR frequency 3200-3600 (broad)

A

O-H stretch

Alcohol and phenol

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2
Q

IR frequency 2500-3000 (broad)

A

O-H stretch

Carboxylic acid

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3
Q

IR frequency 2800-3000

A

C-H stretch

alkane (sp3)

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4
Q

IR frequency 3000-3100

A

C-H stretch

alkene (sp2)

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5
Q

IR frequency 2100-2260

A

C-C (triple bond) stretch

alkyne

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6
Q

IR frequency 1680-1750

A

C=O stretch

Ketones/aldehydes

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7
Q

IR frequency 1730-1750

A

C=O stretch

esters

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8
Q

IR frequency 1710-1780

A

C=O stretch

carboxylic acid

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9
Q

IR frequency 1620-1680

A

C=C stretch

alkene

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10
Q

IR frequency 1450, 1550, 1650

A

C=C stretch

Aromatic

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11
Q

IR frequency 1050-1150

A

C-O stretch

Alcohol, ester, ether

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12
Q

How to determine % yield?

A

(grams starting material * molecular weight of product) / molecular weight of starting material
THEN
(grams of starting material / grams calculated above ) * 100%

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13
Q

IR frequency 1465-1440 or 1390-1365

A

CH3 bend

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14
Q

why was reduced pressure used during the caffeine sublimation step?

A

a reduced pressure allows for sublimation at a lower temperature. (PV=nRT) Caffeine would melt if sublimation was done at atm pressure

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15
Q

will the following sublime or melt?

a solid substance has a vapor pressure of 800 mmHg at its melting point of 80 degrees C

A

the substance will sublime

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16
Q

will the following sublime or melt?

a solid substance has a vapor pressure of 100 mmHg at its melting point of 100 degrees C

A

the substance will melt

17
Q

What is the purpose of using anhydrous sodium sulfate in a solution?

A

to “dry” the solution - to remove any remaining H20 from the solution

18
Q

Which is more polarizable? Br- or Cl-?

A

Br- is more polarizable

19
Q

Which is a better nucleophile in H2O? Br- or Cl-?

A

Br-

20
Q

What is the rate determining step in an SN2 reaction?

A

The nucleophile attacking the R group

very good Nuc needed!

21
Q

What is the rate determining step in an SN1 reaction?

A

formation of the carbocation

22
Q

Will a tertiary (3) substrate undergo SN2, SN1 or both?

A

only SN1

23
Q

Will a secondary (2) substrate undergo SN2, SN1 or both?

A

both

24
Q

Will a primary (1) substrate undergo SN2, SN1 or both?

A

only SN2

25
Q

IR frequency 1480-1440

A

CH2 bend

26
Q

When extracting a solute, it it better to do 1 extraction with a large amount of solvent or multiple extractions with a small amount of solvent? Why?

A

Multiple extractions - you can extract a greater amount of the compound from the aqueous phase

27
Q

Why would you choose one solvent over another for extraction using a centrifuge?

A

It is easier to extract the lower layer from a centrifuge tube, so you want the solvent to be on the bottom layer. You choose a solvent based on density in this case. (Solvent (organic layer) density should be greater than aqueous layer density)

28
Q

When can you do distillation? (or when can you not?)

A

boiling point of products must be lower than the boiling point of reactants to perform a successful distillation

(can not distill if product bp is higher than reactant bp)

29
Q

How can you drive a reaction toward products?

A
  1. a large excess of starting material
  2. distill as you form product
  3. use a dehydrating agent to remove H20 (if H20 is a product of the rxn)
30
Q

Define extraction

A

Removing one or more (desired) components from a solution by transferring that solute into a different solvent that is immiscible with the original solution

31
Q

What does washing do?

A

remove undesired components

32
Q

Explain sublimation

A

At particular pressures, certain substances may transition directly from the solid phase to the gas phase.

33
Q

What is the purpose of an unsaturation test?

A

Unsaturation tests provide a confirmation of the presence of the C=C double bond

34
Q

what is the KEY to a Grignard Reaction? (ie. what can NOT be present?)

A

No Water

35
Q

when will a solid sublime?

A

if its vapor pressure is greater than atm pressure at its melting point

CHEM 354 (2 decks)

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