Need help to calculate the number of moles and the mass of sulfuric acid

Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
icon
Related questions
Question

Need help to calculate the number of moles and the mass of sulfuric acid

36
EXPERIMENT 2: NITRATION OF METHYL BENZOATE TYL BENZOATE
Wash the product once with 10 mL of cold water and then with two 10-mL portions of ice-cold
methanol.
4. Weigh the crude product and then recrystallize the solid from an equal mass of methanol heated to
near boiling. Addition of water is not necessary for this recrystallization. If you use a minimum
amount of hot methanol to dissolve the crude product, the pure substance will crystallize out nicely
when cooled to room temperature. As usual, cool the mixture further in an ice bath for about 5 to
10 minutes.
5. Collect the product, dry it in air, weigh it, take the MP, and the IR spectrum (using the Buck IR
spectrometer). Interpret the IR spectrum and be sure to point out the absorptions which identify the
carbonyl peak, the aromatic and the aliphatic hydrogens, the nitro group and meta substitution. See
Appendix 4 for IR out-of-plane C-H bending vibrations to distinguish between ortho, meta and
para disubstitution. Compare your IR spectrum and MP to what is reported in the literature or the
Internet. Determine the % yield. Hand in your product in a labeled polyethylene bag.
Post-Lab Questions:
1. How many moles of methyl benzoate were you supposed to use? Show your calculations.
2. Why do we get only mono-substitution even though we use a slight excess of nitrating
agent?
3. What would the structure of the product be if anisole (methoxybenzene) were nitrated
instead of methyl benzoate?
4. Why is the temperature of the nitration kept under 15 °C?
entrated sulfuric acid and
5. When methyl benzoate dissolves in sulfuric acid a chemical reaction occurs. How does the
structure of the methyl benzoate change when it is dissolved in sulfuric acid? Give the
mechanism with the use of curved arrows to show the change taking place.
6. Draw all of the resonance structures of the intermediate involved when methyl benzoate is
nitrated in this experiment.
Transcribed Image Text:36 EXPERIMENT 2: NITRATION OF METHYL BENZOATE TYL BENZOATE Wash the product once with 10 mL of cold water and then with two 10-mL portions of ice-cold methanol. 4. Weigh the crude product and then recrystallize the solid from an equal mass of methanol heated to near boiling. Addition of water is not necessary for this recrystallization. If you use a minimum amount of hot methanol to dissolve the crude product, the pure substance will crystallize out nicely when cooled to room temperature. As usual, cool the mixture further in an ice bath for about 5 to 10 minutes. 5. Collect the product, dry it in air, weigh it, take the MP, and the IR spectrum (using the Buck IR spectrometer). Interpret the IR spectrum and be sure to point out the absorptions which identify the carbonyl peak, the aromatic and the aliphatic hydrogens, the nitro group and meta substitution. See Appendix 4 for IR out-of-plane C-H bending vibrations to distinguish between ortho, meta and para disubstitution. Compare your IR spectrum and MP to what is reported in the literature or the Internet. Determine the % yield. Hand in your product in a labeled polyethylene bag. Post-Lab Questions: 1. How many moles of methyl benzoate were you supposed to use? Show your calculations. 2. Why do we get only mono-substitution even though we use a slight excess of nitrating agent? 3. What would the structure of the product be if anisole (methoxybenzene) were nitrated instead of methyl benzoate? 4. Why is the temperature of the nitration kept under 15 °C? entrated sulfuric acid and 5. When methyl benzoate dissolves in sulfuric acid a chemical reaction occurs. How does the structure of the methyl benzoate change when it is dissolved in sulfuric acid? Give the mechanism with the use of curved arrows to show the change taking place. 6. Draw all of the resonance structures of the intermediate involved when methyl benzoate is nitrated in this experiment.
Experiment 2: NITRATION OF METHYL BENZOATE
Purpose: Methyl benzoate is to be nitrated with nitronium ion that is generated in situ.
Theory: The nitration of methyl benzoate is a typical electrophilic aromatic substitution reaction,
with the ester group being an electron withdrawing substituent and a deactivator. This slows down
and prevents di- and tri-nitration, which would yield high energy and potentially explosive
products. Nitric acid, in the presence of sulfuric acid, forms the reactive electrophile, nitronium
ion (NO₂), according to the reaction shown below:
5. Col the product,
HNO3 + 2 H₂SO4
The nitronium ion then attacks the protonated methyl benzoate at the meta position, which releases
a proton from the ring. When the solution is neutralized, the methyl 3-nitrobenzoate crystallizes
out of the solution and can be purified by recrystallization from methanol.
OCH3
OCH3
LOCH 3
Post-Lab Questions:
NO₂+ +
How ma
agent?
H
H
methyl benzoate
→ NO₂ + 2 HSO4 + H3O+
Sure
+
H
-H
NO₂
+
H
H+
NO₂
methyl 3-nitrobenzoate
Procedure: (As usual, prepare a Table of Reagents & Expected Products in your notebook before
you arrive at the lab.)
CAUTION! Concentrated sulfuric acid and nitric acid are corrosive. The liquid and
mist cause severe burns to all body tissue. Inhalation may cause lung and tooth damage.
Avoid skin contact or inhalation of fumes. Reaction of these acids with water is highly
exothermic and can cause the water to boil and "spit." Be careful not to splatter any
water into the concentrated acid! WORK INSIDE A HOOD!
1. In a hood, place 12 mL of concentrated sulfuric acid (equivalent to how many moles?) into a 250-
mL Erlenmeyer flask and cool it to 0 °C with an ice bath. Then add 6.0 mL of methyl benzoate.
Cool the mixture to 0-10 °C.
2. Prepare a nitration mixture by adding an ice-cold solution of 4.0 mL of concentrated nitric acid
(equivalent to how many moles?) to 4.0 mL of cold concentrated sulfuric acid. This solution is
slowly added to the methyl benzoate-sulfuric acid solution, dropwise with the aid of a Pasteur
pipette. During the addition be sure to swirl the flask carefully and keep the pot temperature
between 5 and 15 °C.
3. When all of the nitric acid mixture has been added, allow the mixture to warm up to room
temperature, and then after about 15 minutes, pour the entire mixture onto 50 g of cracked ice in a
250-mL beaker. After all of the ice has melted, isolate the solid product via suction filtration.
35
Transcribed Image Text:Experiment 2: NITRATION OF METHYL BENZOATE Purpose: Methyl benzoate is to be nitrated with nitronium ion that is generated in situ. Theory: The nitration of methyl benzoate is a typical electrophilic aromatic substitution reaction, with the ester group being an electron withdrawing substituent and a deactivator. This slows down and prevents di- and tri-nitration, which would yield high energy and potentially explosive products. Nitric acid, in the presence of sulfuric acid, forms the reactive electrophile, nitronium ion (NO₂), according to the reaction shown below: 5. Col the product, HNO3 + 2 H₂SO4 The nitronium ion then attacks the protonated methyl benzoate at the meta position, which releases a proton from the ring. When the solution is neutralized, the methyl 3-nitrobenzoate crystallizes out of the solution and can be purified by recrystallization from methanol. OCH3 OCH3 LOCH 3 Post-Lab Questions: NO₂+ + How ma agent? H H methyl benzoate → NO₂ + 2 HSO4 + H3O+ Sure + H -H NO₂ + H H+ NO₂ methyl 3-nitrobenzoate Procedure: (As usual, prepare a Table of Reagents & Expected Products in your notebook before you arrive at the lab.) CAUTION! Concentrated sulfuric acid and nitric acid are corrosive. The liquid and mist cause severe burns to all body tissue. Inhalation may cause lung and tooth damage. Avoid skin contact or inhalation of fumes. Reaction of these acids with water is highly exothermic and can cause the water to boil and "spit." Be careful not to splatter any water into the concentrated acid! WORK INSIDE A HOOD! 1. In a hood, place 12 mL of concentrated sulfuric acid (equivalent to how many moles?) into a 250- mL Erlenmeyer flask and cool it to 0 °C with an ice bath. Then add 6.0 mL of methyl benzoate. Cool the mixture to 0-10 °C. 2. Prepare a nitration mixture by adding an ice-cold solution of 4.0 mL of concentrated nitric acid (equivalent to how many moles?) to 4.0 mL of cold concentrated sulfuric acid. This solution is slowly added to the methyl benzoate-sulfuric acid solution, dropwise with the aid of a Pasteur pipette. During the addition be sure to swirl the flask carefully and keep the pot temperature between 5 and 15 °C. 3. When all of the nitric acid mixture has been added, allow the mixture to warm up to room temperature, and then after about 15 minutes, pour the entire mixture onto 50 g of cracked ice in a 250-mL beaker. After all of the ice has melted, isolate the solid product via suction filtration. 35
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 3 steps

Blurred answer
Knowledge Booster
Mole Concept
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Chemistry
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
Chemistry
Chemistry
Chemistry
ISBN:
9781259911156
Author:
Raymond Chang Dr., Jason Overby Professor
Publisher:
McGraw-Hill Education
Principles of Instrumental Analysis
Principles of Instrumental Analysis
Chemistry
ISBN:
9781305577213
Author:
Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:
Cengage Learning
Organic Chemistry
Organic Chemistry
Chemistry
ISBN:
9780078021558
Author:
Janice Gorzynski Smith Dr.
Publisher:
McGraw-Hill Education
Chemistry: Principles and Reactions
Chemistry: Principles and Reactions
Chemistry
ISBN:
9781305079373
Author:
William L. Masterton, Cecile N. Hurley
Publisher:
Cengage Learning
Elementary Principles of Chemical Processes, Bind…
Elementary Principles of Chemical Processes, Bind…
Chemistry
ISBN:
9781118431221
Author:
Richard M. Felder, Ronald W. Rousseau, Lisa G. Bullard
Publisher:
WILEY