Ochem Lab Report 5 Final
docx
keyboard_arrow_up
School
University of Texas, Tyler *
*We aren’t endorsed by this school
Course
3145
Subject
Chemistry
Date
Nov 24, 2024
Type
docx
Pages
12
Uploaded by ProfessorStraw6503
Bromination of Stilbene
by Tuan Nguyen
Pre-lab
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Quest
Tuan Nguyen
Dr. Fjetland
Organic Chemistry Lab: CH220C
10/17/2023
CH 220C - Bromination of Stilbene Lab Report
October 17
th
, 2023
Purpose
The purpose of this lab was to investigate the bromination process of e-stilbene. Typically, in the bromination of E-stilbene, a cyclic bromonium ion intermediate is generated. Subsequently, a bromide ion acts as a nucleophile and attacks this cyclic intermediate, resulting in the formation of meso-stilbene dibromide, which is the primary reaction product. However, besides this dominant reaction, alternative products can also be produced. In addition to the cyclic bromonium ion intermediate, a carbocation intermediate can also be formed. This carbocation is then susceptible to attack by free bromide ions, resulting in the formation of d- and l-isomers of stilbene dibromide. The primary objective of this experiment was to ascertain the prevalent stereochemical form of stilbene dibromide after the bromination of e-stilbene. This determination was to be achieved by analyzing the melting point of the final product, providing insights into the dominant species present in the product.
Data Analysis
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Figure 1. Data Collected During Lab
Table 1. Initial/Final Mass (g), Melting Point (°C), and Percent Yield (%) of Bromination of E-
stilbene to Meso-stilbene Dibromide
Initial Mass (g)
Final Mass (g)
Melting Point (°C)
Percent yield (%)
E-stilbene
0.898g
X
X
X
Meso-stilbene
dibromide
X
0.905g
219°C - 237°C
99.23%
Calculations:
i.
Molar mass of e-stilbene = 180.25 g/mol
ii.
Molar mass of meso-stilbene dibromide = 340.0578g/mol
iii.
Theoretical yield of meso-stilbene dibromide:
-
0.898g e-stilbene x 1mol e-stilbene/180.25g x 1mol meso-stilbene dibromide/ 1mol e-stilbene x 340.0578g/1mol mesto-stilbene dibromide = 1.69g mesto-
stilbene dibromide
iv.
Percent yield of meso-stilbene dibromide:
-
(0.905g/1.69g) x 100 = 53.55%
Discussion
A.
Melting Point
1.
What is the melting point?
-
The initial melting point of the product is 219°C and the final melting point is 237°C. 2.
What does the melting point data tell you?
-
The melting point data of a substance provides information about the substance’s
purity and identity. A sharp and consistent melting point indicates a pure compound, while a broad or inconsistent melting point indicates impurities or a mixture of substances. Additionally, the measured melting point can be compared to known values for the same substance for identification. From the
melting point data, it can be reasonably said that the product is majorly meso-
stilbene dibromide is relatively pure as it is close to the known melting point of the compound, which is 241°C.
3.
Were there any errors?
-
Yes.
a.
What caused them?
-
The errors were that the product was not completely filtered out all of the bromine using DCM and human error like inaccuracy in looking at the melting point on the thermometer using eyes might had happened.
b.
Why do these errors result in the data you received?
-
The filter error led to impurities in the product and can make the melting point lower than the expected value while human error could have led to collecting the
wrong melting point using eyes.
c.
What will do different to avoid the errors in future experiments?
-
To avoid errors in future experiments, more DCM should be used to filter all of the bromine out of the product and the experimenter needs to take a second look at the thermometer before writing down the melting point.
B.
Percent Yield
1.
What is your percent yield?
-
The percent yield for this experiment is 53.55%.
2.
Is this good or bad?
-
This is considered a relatively bad yield because it is below 60%.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
3.
Why?
-
A percent yield above 60% indicates that a majority of the theoretical yield was successfully obtained in the experiment. This high yield suggests efficient and effective experimental procedures, minimal waste or loss during the process, and accurate measurement and control of reactants. However, a low percent yield (below 60%) indicates that there were inefficiencies or losses during the experiment, such as incomplete reactions, side reactions, or losses during product recovery. As such, the percent yield for this experiment is a bad yield.
4.
Were there any errors observed?
-
Yes, the errors could have come from not transferring all of e-stilbene from the weigh boat to the round-bottom flask as there was some e-stilbene left on the weigh boat. Another error was not transferring all of the product from the funnel onto the weight boat after filtering as some of the product was left inside the funnel and on the spatula.
a.
What caused these errors?
-
The cause of these errors is predominantly human error, as the experimenter did not ensure that all the reactant and product are transferred.
b.
Why do the errors give you the results in the experiment?
-
These errors resulted in an incomplete transfer of the starting material and the final product, reducing the actual amount of material present for the reaction and affecting the calculated yield, resulting in a low percent yield.
c.
What will you do to prevent these errors in future experiments?
-
To prevent these errors in future experiments, it is essential to ensure thorough and precise transfer of all substances from one container to another. This could involve using appropriate tools like spatulas and ensuring that all material is scraped and transferred completely. Additionally, careful inspection and double-
checking during transfers must be done to ensure that no material is left behind in the weigh boat or the funnel, this can improve accuracy and give a high percent yield.
Conclusion The melting point analysis conducted in this experiment provided crucial insights into the
product's purity and identity. The initial melting point was recorded at 219°C, with the final melting point at 237°C. A sharp and consistent melting point indicates a pure compound, and the measured melting point, close to the known melting point of meso-stilbene dibromide (241°C), suggests a relatively pure product. However, errors were observed in the experiment, notably incomplete filtration of bromine using dichloromethane (DCM) and potential inaccuracies in reading the thermometer. The errors, particularly the incomplete filtration, resulted in impurities in the product, leading to a lower melting point than the anticipated value. To mitigate such errors in future experiments, it is imperative to use a more thorough filtration process with an adequate amount of DCM to ensure complete removal of bromine. Additionally, careful attention
and a second check on the thermometer reading can enhance the accuracy of the obtained melting point.
In terms of percent yield, the experiment resulted in a yield of 53.55%, which is below the 60% threshold typically considered acceptable. This low percent yield indicates inefficiencies
or losses during the experiment, likely stemming from incomplete transfer of reactants and products. Notably, errors were observed in the incomplete transfer of e-stilbene from the weigh boat to the round-bottom flask and incomplete transfer of the product from the funnel to the weigh boat. These errors led to an incomplete transfer of starting material and the final product, reducing the actual amount available for the reaction and affecting the calculated yield. To prevent these errors in future experiments, thorough and precise transfer of all substances is essential.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Related Documents
Related Questions
Chemistry
I think I understand most of this except for what mechanisms these resemble. Thanks!
arrow_forward
Please answer my question fast
arrow_forward
ФЫ ВАПРОВА ПРО ЛДВА ПРОЛДЫВАПР
ЯЧСМИТЕЧСМИТЬБАСМИТЬБЮ ЯЧСМИ 1
DON'T USE AI | DON'T USE AI |DON'T USE AI | DON'T USE AI |DON'T USE AI |
SOLVE STEP BY STEP IN DIGITAL
Topic: Organic chemistry
FIND THE REACTION MECHANISM FOR:
Oxidation with potassium permanganate
На се сня + KMnO4
cold
он 120
-7
нас сна
+
|
OH
FORMAT
ЙЦУКЕНГ ШУКЕНГШщЗЕНГШЩЗХЪ ЙЦУКЕНГ ШУК
arrow_forward
Why is this reaction considered "green" chemistry and how is it different from a "non-green" bromination? Based on this is this reaction completely "green" chemistry
arrow_forward
Subject-- chemistry
arrow_forward
Question 3
arrow_forward
Nucleophilic Substitution and Elimination. A Worksheet Lab.
Pre-Lab
1. Identify the following organic transformations. Are they "substitutions" or "additions" or
"eliminations"? Write formulas that clearly illustrate you selection. Pay attention to the organic part
of the transformations.
Example.
Br
ultraviolet light
HBr
+
Br₂
formulas:
CsH12
Br2
CsH11Br
HBr
This is a "substitution" reaction. H has been replaced (substituted) by Br
arrow_forward
Which of the following compounds is MOST reactive in an SN1 reaction?
I
-OTs
II
-OTs
III
-OTs
IV
-OTs
А. I
В. IV
C. II
D. II
arrow_forward
Which of the following correctly describes the
movement of electrons in the reaction of
nucleophile (Nu:) with a carbonyl group?
A) Nu:
B)
Nu:
C) Nu:
D) Nu:
ܤ ܗ
+
+
R
R
R
R
R
V
R
R
R
O:
Nu-
Nu-
Nu
Nu
:Ö:*
¹R
R
:Ö:
"R
R
:Ö:
"R
R
:O:
"R
R
arrow_forward
There is great excess of H2O in this reaction.
arrow_forward
Draw the oxidation reaction. Be sure to label initiation, propogation, and termination of free radicals.
150 uL Benzyl Alcohol + 2 mL chlorobenzene + 700 mg N-iodosuccinimide
Allow reaction to mix for 90 minutes with a sunlamp.
arrow_forward
13 Write and name the other product of each of the following reactions:
Acid catalyst
C4H9OH …………………. + H2O
(Concentrated Sulphuric acid)
Acid catalyst
C3H7OH …………………. + H2O
(Concentrated Sulphuric acid)
arrow_forward
Chemistry 23 (iii)
arrow_forward
outinerlegacyUrl=%252Fwe
Your answers are saved automatically.
Remaining Time: 2 hours, 35 minutes, 42 seconds.
* Question Completion Status:
A Moving to another question will save this response.
Question 2
The reaction of sodium ethoxide with iodoethane to form diethyl ether is classified as:
O an electrophilic substitution
O a nucleophilic substitution
O a radical substitution
O an electrophilic addition
A Moving to another question will save this response.
O Type here to search
a.
立
arrow_forward
C5H8 + 7O2 → 5CO2 + 4H2O
type of reaction
arrow_forward
Complete the following 2 step mechanisms by which hydroxyl free radicals catalytically destroys ozone.
X+
-> XÔ +
+ +0-> 02+
Overall O3 +
• [02
->
arrow_forward
SEE MORE QUESTIONS
Recommended textbooks for you
Organic Chemistry
Chemistry
ISBN:9781305580350
Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote
Publisher:Cengage Learning
Related Questions
- Chemistry I think I understand most of this except for what mechanisms these resemble. Thanks!arrow_forwardPlease answer my question fastarrow_forwardФЫ ВАПРОВА ПРО ЛДВА ПРОЛДЫВАПР ЯЧСМИТЕЧСМИТЬБАСМИТЬБЮ ЯЧСМИ 1 DON'T USE AI | DON'T USE AI |DON'T USE AI | DON'T USE AI |DON'T USE AI | SOLVE STEP BY STEP IN DIGITAL Topic: Organic chemistry FIND THE REACTION MECHANISM FOR: Oxidation with potassium permanganate На се сня + KMnO4 cold он 120 -7 нас сна + | OH FORMAT ЙЦУКЕНГ ШУКЕНГШщЗЕНГШЩЗХЪ ЙЦУКЕНГ ШУКarrow_forward
- Nucleophilic Substitution and Elimination. A Worksheet Lab. Pre-Lab 1. Identify the following organic transformations. Are they "substitutions" or "additions" or "eliminations"? Write formulas that clearly illustrate you selection. Pay attention to the organic part of the transformations. Example. Br ultraviolet light HBr + Br₂ formulas: CsH12 Br2 CsH11Br HBr This is a "substitution" reaction. H has been replaced (substituted) by Brarrow_forwardWhich of the following compounds is MOST reactive in an SN1 reaction? I -OTs II -OTs III -OTs IV -OTs А. I В. IV C. II D. IIarrow_forwardWhich of the following correctly describes the movement of electrons in the reaction of nucleophile (Nu:) with a carbonyl group? A) Nu: B) Nu: C) Nu: D) Nu: ܤ ܗ + + R R R R R V R R R O: Nu- Nu- Nu Nu :Ö:* ¹R R :Ö: "R R :Ö: "R R :O: "R Rarrow_forward
- There is great excess of H2O in this reaction.arrow_forwardDraw the oxidation reaction. Be sure to label initiation, propogation, and termination of free radicals. 150 uL Benzyl Alcohol + 2 mL chlorobenzene + 700 mg N-iodosuccinimide Allow reaction to mix for 90 minutes with a sunlamp.arrow_forward13 Write and name the other product of each of the following reactions: Acid catalyst C4H9OH …………………. + H2O (Concentrated Sulphuric acid) Acid catalyst C3H7OH …………………. + H2O (Concentrated Sulphuric acid)arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning
Organic Chemistry
Chemistry
ISBN:9781305580350
Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote
Publisher:Cengage Learning