P.S. The weight of the product calculated 29.896 -29.436 = 0.46 g The melting po
ID: 983202 • Letter: P
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P.S. The weight of the product calculated 29.896 -29.436 = 0.46 g The melting point 105 for my product (1-bromo -4-nitrobenzene) I think Experiment #19 Electrophilic Aromatic Substitution: Nitration of Bromobenzene In the present experiment, you will synthesize p-bromonitrobenzene by an electrophilic aromatic substitution reaction of bromobenzene. The bromo group is an ortho and para director. The haloge atoms are weak deactivators for electrophilic aromatic substitution reactions. The electrophile will nitronium cation. Aromatic nitro groups have two strong infrared absorptions near 1350 and 1520 The presence of these two peaks for a nitro group on an aromatic ring is critical for supporting the nitration of an aromatic compound. A reference spectrum of nitrobenzene has been included to sho the location of these two prominent peaks. Recrystallization will be used to purify your product Infrared spectroscopy and melting point will be used to characterize the product Br Br H2SO4 HNO3 NO2 Bromobenzene p-Bromonitrobenzene MW. doimL M.PG BP.G Refractive Index 157.0 1.491 Substance 156 1-Bromo-2-nitrobenzene 202.0 1-Bromo-3-nitrobenzene 202.0 1-Bromo-4-nitrobenzene 202.0 43 17 127 Nitrating reagent (1:1 Concentrated Nitric acid/Concentrated sulfuric acid) Reagent alcohol SAFETY PRECAUTIONS Safety goggles are required for performing this lab exercise. Minimize the breathing of any vapors and skin contact of chemical reagents The Nitrating reagent is very strongly acidie and a very strong oxidizing agent. Handle with extreme care. Wash any skin exposed to the nitrating reagent immediately, and treat with a paste of sodium bicarbonate. Handle hot lab items with proper protection Dispose chemical waste according to your instructor's directions Wash your hands thoroughly when the lab exercise has been completed. Synthesis of Bromonitrobenzene 1. Place 2 mL of the nitrating reagent in a 5-mL, conical vial containing a spin vane HIGHLY AGGRESSIVE and CORROSIYE Add 300 L of bromobenzene into the 5-mL vial and seal vial with green cap and extra orange septum immediately 2, 64Explanation / Answer
ANSWER
The theoretical yeild of the copound can be had from the stiochiometry of the reaction.
Bromobenzene + HNO3 --------> p-bromonitrobenzenzene
Amount of BROMOBENZENE TAKEN = 300 micro liter = 300 X 10-6 L
mass of bromobenzene = density X Volume
volume = 300 X 10-6 L = 300 X 10-3 mL
density = 1.5g/mL
Mass = 300 X 10-3 X 1.5 = 450.0 X 10-3 g = 0.45g
As per the stiochiometry of the reaction one mole or 157.0g of Bromobenzene gives one mol or 202.0 g of
p-bromonitrobenzenzene
Therefore 1g of bromobenzene will give 202.0 / 157.0 = 1.29g of p-bromonitrobenzenzene
Hence 0.45g of bomobenzene will give 1.29 X 0.45 = 0.5805g
Hence theoretical yeild = 0.5805
Practical yeild = 0.46g
% yeild = (theoretical yeild / practical yeild ) X 100 = (0.46 / 0.5808) X 100 = 79.2%
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