AZARDS ABLE OF REAGENTS - Amazon...
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The Grignard Reaction May 30 2012
Cheryl Lee 100191898
HAZARDS / TABLE OF REAGENTS
Chemical Name / Molecular / Structural Formula
Physical Appearance | bp | mp
Molecular Weight | Density | Solubility
Hazards
Grignard reagent | Phenylmagnesium bromide solution, C6H5BrMg
Clear, colorless solution
F.W.181.31 g/mol Conc: 3.0 M in diethyl ether Density: 1.134 g/mL at 25 °C Solubility: Reacts explosively w/ H2O
Extremely flammable; Corrosive
1,1-diphenylethanol, C14H14O
white to pale yellow crystals bp: 162 °C mp: 77-81 °C
MW: 198.26 Vapor Density: 6.84 Solubility: H2O soluble
Eye, skin, GI tract, respiratory tract irritant
Acetophenone, C6H5COCH4
Colorless to light yellow liquid Boiling Point: 201.7°C (395.1°F) Melting Point: 19.7°C (67.5°F)
MW: 120.16 g/mole
Vapor Density: 4.1 (Air = 1)
Solubility: Soluble in methanol, diethyl ether. Partially soluble in cold water, hot water.
Combustible; Eye, skin, GI tract, respiratory tract irritant
Biphenyl (C12H10)
Colorless leaflets; pleasant peculiar odor mp/bp: 68.93 / 256.1 °C
MW: 154.207 g/mol Solubility: I H2O; s EtOH, eth; vs bz, ctc. MeOH
Harmful if inhaled or absorbed through skin
The Grignard Reaction May 30 2012
Cheryl Lee 100191898
Chemical Name / Molecular / Structural Formula
Physical Appearance | bp | mp
Molecular Weight | Density | Solubility
Hazards
Bromobenzene, C6H5Br
Clear, colorless liquid Boiling Point: 156.2°C (313.2°F) Melting Point: -30.6°C (-23.1°F)
MW: 157.02 g/mole Vapor Density: 5.41 (Air = 1) Solubility: Soluble in methanol, diethyl ether. Very slightly soluble in cold water.
Very hazardous in case of skin contact (irritant, permeator), of eye contact (irritant), of inhalation.
Dichloromethane9 CH2CL2
Colorless liquid Very soluble in benzoic acid Eye and skin irritant; respiratory tract irritation
Sulfuric acid, H2SO4
Clear colorless to yellow liquid bp: 290-338 °C mp: 10 °C
MW: 98.07 Vapor Density: 3.38 (air=1) Solubility: Soluble w/ much heat
Causes eye and skin, digestive and respiratory tract burns;
Iodine, I2
Purple solid with metalic luster. (Dark.) Boiling Point: 184.4°C (363.9°F) Melting Point: 113.7°C (236.7°F)
MW: 253.81 g/mole Dispersion Properties: See solubility in water, methanol, diethyl ether. Solubility: Easily soluble in diethyl ether. Soluble in methanol. Very slightly soluble in cold water, hot water.
Eye and skin irritant; respiratory tract irritation; non-flammable
Magnesium sulfate anhydrous MgSO4 anhydrous10
Solid; non-flammable Easily soluble in cold water Slightly hazardous in case of skin contact (irritant), of eye contact (irritant), of inhalation.
The Grignard Reaction May 30 2012
Cheryl Lee 100191898
Chemical Name / Molecular / Structural Formula
Physical Appearance | bp | mp
Molecular Weight | Density | Solubility
Hazards
Methyl benzoate, C8H8O2
colourless to light yellow fragrant liquid bp: 199°C mp: -12°C
MW: 136.15 g/mol Density: 1.088 g/mL at 20 °C (lit.) Solubility: Slightly soluble in water. Hydrolyzes slowly in contact with water
Combustible. Incompatible with strong oxidizing agents, strong acids, strong bases.
Eye and skin irritant; respiratory tract irritation;
Sodium sulfate anhydrous, Na2SO4
White crystalline powder Boiling Point: 1100°C (2012°F)Melting Point: 888°C (1630.4°F)
MW: 142.06 g/mole Solubility: Soluble in cold water, hydrogen iodide, and glycerol.. Insoluble in alcohol.
Non-flammable; Eye and skin irritant; respiratory tract irritation;
Petroleum Ether
Clear, colorless liquid Flammable bp: 60°C mp: -73°C
Negligible solubility in H2O Skin and eye irritant ; Skin permeator
Triphenylmethanol, C19H6O
White powder bp: 360 °C mp: 160-163 °C
MW: 260.33 g/mol Solubility: Insoluble in H2O; Combustible. Incompatible with oxidizing agents, acids, acid chlorides, acid anhydrides.
The Grignard Reaction May 30 2012
Cheryl Lee 100191898
Flow Chart
Set up Apparatus /
Starting Materials
o Obtain clean dry glass-ware from oven: boiling tube (25 mm x 200 mm), two
Pasteur pipettetes, one test tube (10 mL)
o Handle hot glass-ware w/ oven gloves
o Ensure all glass-ware are DRY
o Prep in FUME HOOD 1 mL bromobenzene in 5 mL anhydrous diethyl ether in
10 mL test tube
o Use Pasteur pipettetes to measure out the amounts
Prep Grignard
Reagent | Initiate
reaction
o Place ~ 0.30 g Magnesium turnings into dry boiling tube
o Add ~ 2 mL of prepared bromobenzene solution in dry ether
o Mount/clamp test tube on ring stand in FUME HOOD
o Wait till the mixture boil/bubble and become grey/turbit
o If no bubbling, initiate reaction by crushing small magnesium w/ clean dry
stirring rod against test tube bottom
o Alt: add small crystal of iodine to test tube
o Place test tube in warm water bath as needed
o Ensure diethyl ether not boil off to MAINTAIN Vol
o Cool test tube in a beaker of H2O if reaction becomes too vigorous
o After several minutes, add remaining 4 mL ethereal bromobenzene solution
in small portions to maintain reaction rate
o Upon stopping of spontaneous boiling, place test tube in a beaker of warm
water (40-50 °C) for 5 Min
The Grignard Reaction May 30 2012
Cheryl Lee 100191898
Prep
Triphenylmethanol
o Dissolve 0.6 mL methyl benzoate in 5 mL of anhydrous
ether
o Add solution of methyl benzoate DROPWISE to Grignard
reagent solution (NOTE COLOR CHANGES)
o Avoid evaporation by adding more dry ether to maintain
initial solvent volume
o Reaction complete when bubbling stops
o Add ice and 6 M H2SO4 to destroy excess magnesium a
DROPPER full at a time until frothering stops
o Place reaction tube in warm water bath (~ 50 C) until
boiling stops to Drive off remaining solvent
Prep 1,1-Diphenylethanol
o Dissolve 1.0 mL of
acetophenone in 5 mL
anhydrous ether
o Add acetophenone solution
dropwise to Grignard reagent
solution (note any COLOR
CHANGES)
o Maintain initial solvent
volume!! Prevent excess
solvent evaporation by adding
more dry ether
o Reaction would be complete
when bubbling stops
The Grignard Reaction May 30 2012
Cheryl Lee 100191898
Isolation of alcohol
product o Add 10 mL DCM and 15 mL H2O
to reaction mixture
o Transfer contents to sep funnel
o Rinse boiling tube w/ H2O and
DCM (small portions)
o Combine washings in sep funnel
o Mix layers
o Drain bottom organic layer via
stopcock
o Pour top aqueous layer into beaker
via funnel top (discarded later)
o Wash organic layer w/ 5 mL of 10
% NaHCO3 and mix
o Remove organic layer (bottom layer)
and throw out aqueous layer
o Wash organic layer again w/
another 5 mL of H2O
o Dry w/ MgSO4 or Na2SO4 to get
rid of DCM
o Filter dried organic layer by gravity
The Grignard Reaction May 30 2012
Cheryl Lee 100191898
o Further evaporation by adding 5 mL
petroleum ether and warming on
hot water bath
o Place Erlenmeyer flask in ice bath to
allow crystal precipitation
o If not, then transfer solvent/crystals
mixture to 5 mL round bottom flask
o Attach Claisen head
o Concentrate mixture under reduced
pressure
o Warm flask slightly to facilitate
evaporation
o Wash recovered crystals 2X w/
small amounts of petroleum ether
o Save filrate for TLC and GC
analysis
o Determine mass of crude product
o Save some for mp analysis
o Dissolve remaining white crystalline
product in minimal amount of
DCM in 10 mL Erlenmeyer flask
Add ~ 5 mL petroleum ether
The Grignard Reaction May 30 2012
Cheryl Lee 100191898
o Recrystallize at rm temp
o Recrystallize in ice water bath to obtain alcohol product
o Collect crystals by vacuum filtration
o Obtain second crop of crystals Transfer mother liquor to separate 10 mL Erlenmeyer flask
o Evaporate on hot water bath for a few seconds or until crystals precipitate
o Place in ice water bath
o Use remaining mother liquor to collected crystals by vacuum filtration
o Wash combined crystals in petroleum ether (2x2 mL)
o Allow to dry
Analysis of alcohol products
o Obtain mass
o Obtain mp of dried product
o Collect IR spectrum of starting material used
o Collect IR spectrum for alcohol product
o Submit product in sample bag
o Run TLC analysis (5:1 petroleum ether/ethyl acetate as eluting solvent)
o On alcohol product
o On filtrate from initial crystallization (may be diluted by a factor of 100)
o Authentic biphenyl
o GC analysis of filtrate from initial crystallization from each Grignard process
The Grignard Reaction May 30 2012
Cheryl Lee 100191898
Balanced Equation:
Reaction Mechanism:
CHEM 322L Experiment 1: Grignard Reaction 2
and adds to the carbonyl carbon forming an alkoxide. In the workup of the
reaction, an acid is added so that the alkoxide is protonated to form the alcohol
product. See Figure 2 for the general reaction.
RC
R
O
R R
OHR1) RMgX
2) H2O
1) addition
2) protonation
yields a 3o
alcohol
RC
H
O
R R
OHH1) RMgX
2) H2O
1) addition
2) protonation
yields a 2o
alcohol
R Xether
R MgX
Mg
R MgX
Figure 1. General reaction for the Grignard reaction.
In this experiment, you will be performing a Grignard reaction (see Figure 3).
You will first synthesize the Grignard reagent starting from bromobenzene and
magnesium using ether as the solvent. The reaction and thus the reagent are
moisture sensitive so you will be using anhydrous ether. In the second step, you
will be adding your Grignard reagent to benzophenone to form triphenylmethanol.
Figure 3. The overall reaction of this experiment.
Br
Bromobenzene
bp 156 oC
M.W. 157.02
density 1.491 g/mL
M agnes iu m A t. W. 2 4 . 31
Phenylm agne s iu m br omidean inter m ediat e b u t n ot isolated
+
1) ether+
T r iphe ny lm e thanol
mp 1 60 - 16 3
oC
M . W . 26 0. 34
2) dilute HCl
M gB r
M g B r
Pheny lm a gn es ium br o m ide
anhydrous
diethyl ether(ether)
O
Benzophenone
mp
48-49
oC
M.W. 182.22 .
O H
M g
The Grignard Reaction May 30 2012
Cheryl Lee 100191898
Reference:
1. Kwantlen Polytechnic University CHEM 2320/2420 Lab Manual (2011)
2. Zubrick, J. The Organic Chem Survival Manual: A Student’s Guide to Techniques, 7th ed.; Wiley: New Jersey, 2008.
3. MSDS for Phenylmagnsium bromide. http://www.sigmaaldrich.com/catalog/product/ALDRICH/257117?lang=en®ion=CA
(accessed May 29 2012)
4. MSDS for 1,1-diphenylethanol. https://fscimage.fishersci.com/msds/79640.htm (accessed May 29 2012)
5. ScienceLab.com, Inc. MSDS for Acetophenone. http://www.sciencelab.com/msds.php?msdsId=9922778 (accessed May 29 2012)
6. MSDS for Bromobenzene. http://www.sciencelab.com/msds.php?msdsId=9927463 (accessed May 29 2012)
7. MSDS for Sulfuric acid. http://www.sciencelab.com/msds.php?msdsId=9927547 (accessed May 29 2012)
8. ScienceLab.com, Inc. MSDS for Sodium Bicarbonate. http://www.sciencelab.com/msds.php?msdsId=9927258 (accessed May 22
2012)
9. MSDS for Sodium sulphate anhydrous. http://www.sciencelab.com/msds.php?msdsId=9927278 (accessed May 29 2012)
10. MSDS for Triphenylmethanol. http://www.chemicalbook.com/ChemicalProductProperty_EN_CB3335936.htm (accessed May 29
2012)
11. MSDS for Petroleum Ether. http://www.sciencelab.com/msds.php?msdsId=9927688 (accessed May 22 2012) 12. Chem Department. The University of Missouri – Kansas City. The Grignard Reaction.
http://d.web.umkc.edu/drewa/Chem322L/Handouts/EXP%201%20grignard_reaction%20SP2008.pdf (accessed May 22 2012)