Lab Exam Final Flashcards
1
Q
What are the correct steps for washing glassware
A
1- acetone
2- soap and water
3- acetone
2
Q
How to dry glassware standard
A
on papertowel to air dry
3
Q
How to dry glassware for moisture sensitive reactions
A
flame drying
4
Q
first number pf taper glassware
A
diameter of top joint
5
Q
second number of tapered glassware
A
inner length of the joint
6
Q
weighing solids
A
weigh paper on scale, tare, add and remove solid till amount is reached
7
Q
hot water baths
A
used for heating low boiling liquids
8
Q
How to hold a pipette
A
vertically to prevent spilling and filling the bulb
9
Q
How does 250 mg look on a gram scale
A
0.250 g
10
Q
How do you weigh a liquid
A
Use the mass difference
11
Q
How to prepare paper for gravity filtration
A
Flute it
12
Q
What goes on filter flask for vacuum filtration
A
Büchner funnel and adapter
13
Q
What is the purpose of vacuum filtration
A
To remove liquid mixture from final product/ solid
14
Q
Where to dispose of organic solvents
A
organic liquid waste
15
Q
Where to dispose of aqueous solvents go
A
aqueous liquid waste
16
Q
where does paper go
A
contaminated paper wsate
17
Q
where does glass go
A
yellow broken glass bin
18
Q
where do tlc plates go
A
TLC waste bin
19
Q
where do solids and boiling stones go
A
solid waste bin
20
Q
where does clean acetone rinse go
A
acetone recovery
21
Q
where does silica go
A
silica waste bin
22
Q
what goes on filter flask for reduced pressure evaporation
A
cork or Buchner funnel filter paper and adaptor
23
Q
what is the purpose of reduced pressure evaporation
A
remove liquid from solid, remove the solvent from sample or concentrate it
24
Q
miscible
A
describes two liquids that are soluble in each other
25
density of water
1 g/mL
26
what two solvents are denser than water
DCM and chloroform
27
what is the purpose of a variac
the heating mantel can not be connected directly to the outlet or else it will become too hot and will easily vaporize contents of flask,variac which runs full power put cycles on and off prevents from happening
28
how to adjust setup if liquid is boiling too much or bumping
lower the lab jack & mantle, and can turn down variac
29
purpose of stir bars
stirring and preventing bumping
30
reflux set up
lack jack, mantle, stir bar, variac, RBF, condenser, tubing, hose clamps
31
for refill which tube does water enter from
the bottom tube
32
recrystallization steps
1. Dissolve the solid in a minimal amount of hot solvent.
2. Allow the solution to cool to room temperature.
3. Cool further in an ice bath.
4. Filter the mixture through a Buchner funnel to collect the solid.
5. Weigh the solid to get a mass of compound recovered
6. Measure the melting point
33
two solvent recrystallization
finding two pair of miscible solvents
1. Choose solvent A that is very soluble to the compound. Choose solvent B that is does not dissolve the compound at all.
2. Add hot solvent A to test tube containing compound. Heat, shake, dissolve the compound.
3. Add hot solvent B. Reheat
4. Cool solution
5. Remove solvent via Buchner funnel to obtain crystals
34
TLC
thin layer chromatography
35
how to adjust eluent system if Rf is too low ***** spots too close to baseline***????
increase the polarity of eluent
36
what stains do we use for TLC
potassium permanganate, PMA
37
Aqueous or organic layer on top layer for separator funnel
Density is checked, typically organic is on the top
38
What is sodium sulphate used as
a drying agent
39
Seperation methods
Reduced pressure evaporation, vacuum filtration, gravity filtration
40
how do impurities effect melting point
if more than 10 degree difference then the product is impure
41
Info from NMR spectrum to identify
number of signals, chemical shift, integration, multiplicity
42
NMR downfield
left, desheilded
43
TMS peak on NMR
0
44
Solvent NMR peak
7.2 ppm
45
Integration NMR
area under the curve, proportional to the number of protons contained under the peak
46
NMR coupling
double peak on one signal, when nearby protons have a magnetic field that affect effective magnetic field. Number of peaks depends on the number of protons that are nearby and unique combinations of their spins
Spin-spin splitting is another name
n + 1 rule predicts number of peaks. N is the number of neighbors. Neighbors don't include chemically equivalent H's)
47
spin coupling
elimination of spin- spin splitting by constantly irradiating one type of nuclei at its resonance frequency
48
coupling constant
distance between the peaks of a multiplet
49
diasteromers
stereoisomers that are not mirror images
50
stereoisomers
molecules with the same chemical formula but different spatial arrangement
51
enantiomers
isomers that are mirror images of each other
52
what does chemical shift provide
info about the structural environment surrounding the protons producing the signal
53
NMR symmetry
a symmetrical compound will have one signal for multiple protons not on the same carbon
54
spin decoupling occurs
in the proton NMR of alcohols, amines, and carboxylic acids, resulting in the OH and NH protons appearing as broad singlets
55
vicinal
substituents attached to adjacent carbons
56
long range
attached to non adjacent carbons
57
Diels-Alder reaction
a [4+2] cycloaddition reaction, 2 pi bonds broken, 2 sigma bonds formed, concerted
58
dienophile
an alkene that reacts with a diene in a a diets-alder reaction
59
diene
two double bonds
60
dials alder mechanism
draw reaction scheme
61
what is in the waterless condenser
ethylene glycol
62
purpose of methanol in lab 3
extract crystals
63
green chemistry
uses materials and processes that are intended to prevent or reduce pollution at its source
64
lab 3
green chemistry and diets alder cycloaddition
65
lab 4
dreidel crafts acylation
66
dreidel crafts acylation mechanism
draw mechanism
67
friedel crafts alkylation mechanism
for CH3Cl and 1 degree RCl, the Lewis acid-base complex itself serves as the electrophile for electrophilic aromatic substitution
* with 2 and 3 degree RCl, the Lewis acid-base complex reacts further to give a 2 or 3 degree carbocation, which serves as the electrophile; carbocation formation occurs only with 2 and 3 degree alkyl chlorides because they afford more stable carbocations
68
friedel crafts acylation reagents
acyl chloride and AlCl3
69
FeCl3 vs AlCl3
AlCl3 is difficult to store and more hygroscopic than FeCl3
70
drawback of alkylation
further alkylation can occur, alkyl groups can rearrange into more stable carbo cations
71
limiting agent in lab 4, acylation
4 methods benzoyl chloride
72
anisole
draw image
73
purpose of gas trap in lab 4
to catch Hal gas
74
purpose of water in lab 4
quenching
75
purpose of ethyl acetate in lab 4
solvent
76
lab 5
Grignard reation
77
Grignard reagent
an alkyl magnesium halide that is used to make carbon-carbon bonds
78
Lab 5 purpose of THF
reaction solvent
79
Issue with Grignard reagents
they decompose in protic solvents, alcohols, and amines to form alkanes
80
Solvents that Grignard reagents won't react with
diethyl ether or THF
81
THF
draw image
82
Grignard reaction mechanism
draw mechanism
83
organometallic compounds
compounds that contain carbon- metal bonds
84
wurtz coupling
coupling of two alkyl or cycloalkyl halides, produces dimers
85
lab 5 limiting reagent
benzophenone
86
side reactions of Grignard reaction
reactions with aldehydes
reactions with acyl chlorides and esters
reactions with ketones and carbon dioxide
reactions with alkyl bromide (wurtz coupling)
87
Grignard reactions with aldehydes
form secondary alcohols
88
Grignard reactions with acyl chlorides and esters
form corresponding alcohol
89
Grignard reactions with ketone and carbon dioxide
form tertiary alcohols and carboxylic acids
90
volume calculation
weight/ density
91
molarity
the number of moles of solute per litre of solution
92
% yield calculation
actual yield theoretical yield x 100
93
% recovery calculation
amount recovered/ initial amount x 100
94
% purity calculation
amount of pure/ amount of crude x 100
95
lab 6
borohydride reduction
96
reduction
gain of electrons, removal of O or addition of H
97
reduction of carboxylic acids
primary alcohols
98
reduction of aldehydes
primary alcohols
99
reduction of esters
primary alcohols
100
reduction of amides
primary amines
101
reduction of ketones
secondary alcohols
102
reducing agents
LiAlH4 NaBH4
103
What can LiAlH4 reduce
aldehydes, ketones, esters, carboxylic acids
104
what can NaBH4 reduce
aldehydes and ketones
105
reduction mechanism
draw mechanism
106
lab 6 limiting reagent
vanillin alcohol
107
limiting reagent
the reactant use up first in a reaction
108
NaOH purpose lab 6
solvent
109
why is NaOH a solvent for reductions
reducing agents are unstable in acids
110
Lab 6 HCl purpose
quenching
111
borohydride reduction mechanism
draw mechanism
112
lab 7
esterfication
113
esterfication
the reaction of an alcohol with a carboxylic acid to produce an ester and water
114
esterification mechanism
draw mechanism
115
TMEDA
N,N,N,N tetramethylethylene diamine (draw)
116
aldehyde
draw
117
lab 7 product polarity
product is less polar (higher up on TLC plate)
118
lab 8
aldol condensation
119
aldol
contains both aldehyde and alcohol functional groups
120
aldol condensation
A reaction in which an aldehyde or ketone acts as both the electrophile and nucleophile, resulting in the formation of a carbon-carbon bond in a new molecule called an aldol.
121
lab 8 aldol condensation catalyst
acid or base
122
aldol condensation mechanism
draw mechanism
123
