From the lab hand-out: “In this experiment, you will synthesize stilbene dibromide by reacting the alkene,...
From the lab hand-out: “In this experiment, you will synthesize stilbene dibromide by reacting the alkene, trans-stilbene, with Br2 formed in situ from pyridinium tribromide (Figure 1). This reaction takes place and produces two stereocenters, therefore up to three products can be formed; S,S and R,R enantiomers and/or racemic mixture of R,S and S,R which are meso compounds (by definition a meso compound is a molecule with multiple stereocenters that is superimposable on its mirror image)…”
After you complete your synthesis you will use melting point to determine if you produced the S,S and R,R enantiomers or the meso compound, as the melting points are substantially different for the S,S and R,R enantiomers when compared to the melting point of the meso compound.
Pre-lab Question:
Q1) State a hypothesis related to the stereochemical outcome of the bromination of trans-stilbene (Will the reaction produce the S,S and R,R enantiomers or the meso compound?). Your hypothesis must be supported with at least three scientifically founded ideas.
Homework Answers
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From the lab hand-out: “In this experiment, you will synthesize
stilbene dibromide by reacting the alkene,...
alswering these questions. 1. If the bromination of trans-stilbene proceeded by syn addition what isomer(s) of...
alswering these questions. 1. If the bromination of trans-stilbene proceeded by syn addition what isomer(s) of stilbene dibromide would be formed? 2. If the bromination of trans-stilbene proceeded by anti addition what isomer(s) of stilbene dibromide would be formed? 3. Which isomer(s) of stilbene dibromide would be formed if the reaction followed Mechanism 4? Mechanism 4: Bromination is a multi-step process. In this mechanism, the pi bond attacks the bromine molecule as in Mechanism 1. Some time after the carbocation...
Discussion Questions: 1. a) Carefully draw a three-dimensional structure of each stereoisomer of stilbene dibromide. Do...
Discussion Questions: 1. a) Carefully draw a three-dimensional structure of each stereoisomer of stilbene dibromide. Do not include any identical structures. b) Identify the enantiomeric pair, and identify one pair of structures that are diastereomers. 2. Give careful stereo-drawings representing the complete mechanism for the reaction of cis-stilbene with bromine. Remember to show the two different modes of anti-attack that are possible, depending on whether you add the bromine from above to the left-hand or the right-hand carbon of the...
Although the stereochemistry of the alkene cannot be determined from an NMR spectrum, it can be...
Although the stereochemistry of the alkene cannot be determined from an NMR spectrum, it can be deduced from the stereochemistry of the final dibromide product (see Chapter 7 in Carey). 1) clearly depict allof the stereoisomers for the final dibromide that could be formed from each stilbene isomer; 2) for the dibromide products, clearly label each chiral carbon with the appropriate R/S designation; 3) be sure to identify which dibromides form from which stilbene; 4) when two chiral centers are...
Look up and draw the mechanism for the addition of Br2 to double bonds. Reference the...
Look up and draw the mechanism for the addition of Br2 to
double bonds. Reference the source from which you acquired the
mechanism.
Give the IUPAC name of the major product in the above-mentioned
reaction.
Draw the major product of obtained in the addition of Br2 to
stilbene.
Is this isomer chiral? What would be the optical rotation if
this sample was placed in a polarimeter?
Would a student obtain the same product if you started with
cis-stilbene instead of...
lab G: (e)- stilbene, pyridinium tribromide, meso-stilbene dibromide, potassium hydroxide, triethylene glycol, diphenylacetylene, ethanol Mole Table...
lab G: (e)- stilbene, pyridinium tribromide, meso-stilbene
dibromide, potassium hydroxide, triethylene glycol,
diphenylacetylene, ethanol
Mole Table Drawn immediately beneath the Overall Reaction, the Mole Table is used to calcu late the theoretical yield of your product using stoich iometry. All calculations are to be shown in the "Calculations" section. Each column refers to the structure drawn above it. Please cite the source of Mole Table information stated in the Mole Table - refer to the example below for format. As...
please help with filling out this table and answering 8 questions Data Table Br H CH2CH3OH...
please help with filling out this table and answering 8
questions
Data Table Br H CH2CH3OH N-H Bry Chemicals H (E)-Stilbene Ethanol Pyridinium tribromide CsH.Br3N Stilbene Dibromide C14H12Br2 Molecular Formula C14H12 CHO Molecular Weight 180.25 g/mol 46.07 g/mol 319.82 g/mol 340.06 g/mol Physical Properties White solid Clear liquid White solid White solid Melting Point 122-124 °C N/A 127-133 °C 241-243 °C Amount needed 0.25 g 10 mL 0.5 g Mole needed 1.39 mmol 1.56 mmol Amount Used Moles Used Amount...
1. Most of the class will be brominating trans-stilbene (part B) and the rest cis-stilbene (part...
1. Most of the class will be brominating trans-stilbene (part B) and the rest cis-stilbene (part A). For this assignment write a detailed procedure in your lab notebook for Part B. Upload a picture/scanned copy (5 pts). Tip: If you write the procedure down the left half of the page, you can leave space to record your measurements/observations down the right side of the page. If you end up using cis-stilbene in the experimental there will only be a few...
2. Your lab manual proposes 3 possible mechanisms for bromination. During this lab, you will determine...
2. Your lab manual proposes 3 possible mechanisms for bromination. During this lab, you will determine which iroduct(s) formed during the bromination of stilbene. (9 pts) a. Four possible products from the bromination of trans-stilbene are shown below. Label the chiral centers as Sor R. Ph Br Br H iph H Phil Br Ph Ph Br B. HINH Philiph Phí By HP b. The enantiomer of structure A is: c. The enantiomer of structure Dis: d. Ust the letters corresponding...
here is the procedure if needed EXPERIMENT 8: BROMINATION OF TRANS-STILBENE glacial acetic acid Objective: Execute...
here is the procedure if needed
EXPERIMENT 8: BROMINATION OF TRANS-STILBENE glacial acetic acid Objective: Execute first step of two-step sequence to transform an alkene into an alkyne via a dihalide intermediate and use infrared spectroscopy to identify functional groups PRELAB NOTEBOOK: In the laboratory notebook, write the overall experimental objective, chemical equation(s), reaction mechanism (consider all possible stereoisomers), draw a diagram or outline of the procedural steps, and complete the chemical safety table for all chemicals. 1. Why is...
Postlab Questions Answer the following questions on a separate sheet or in your lab notebook. Make...
Postlab Questions Answer the following questions on a separate sheet or in your lab notebook. Make sure that the copy page is readable! D) Calculate the percentage yield for both reactions. Show all calculations. 2) What is the color of the reaction at the beginning of reaction? What causes the color? 3) Why do you dissolve maleic acid in diethyl ether and fumaric acid in water? 4) Give the complete reaction mechanisms for the formation of meso and racemic 2,3-...
alswering these questions. 1. If the bromination of trans-stilbene proceeded by syn addition what isomer(s) of stilbene dibromide would be formed? 2. If the bromination of trans-stilbene proceeded by anti addition what isomer(s) of stilbene dibromide would be formed? 3. Which isomer(s) of stilbene dibromide would be formed if the reaction followed Mechanism 4? Mechanism 4: Bromination is a multi-step process. In this mechanism, the pi bond attacks the bromine molecule as in Mechanism 1. Some time after the carbocation...
Discussion Questions: 1. a) Carefully draw a three-dimensional structure of each stereoisomer of stilbene dibromide. Do not include any identical structures. b) Identify the enantiomeric pair, and identify one pair of structures that are diastereomers. 2. Give careful stereo-drawings representing the complete mechanism for the reaction of cis-stilbene with bromine. Remember to show the two different modes of anti-attack that are possible, depending on whether you add the bromine from above to the left-hand or the right-hand carbon of the...
Look up and draw the mechanism for the addition of Br2 to
double bonds. Reference the source from which you acquired the
mechanism.
Give the IUPAC name of the major product in the above-mentioned
reaction.
Draw the major product of obtained in the addition of Br2 to
stilbene.
Is this isomer chiral? What would be the optical rotation if
this sample was placed in a polarimeter?
Would a student obtain the same product if you started with
cis-stilbene instead of...
lab G: (e)- stilbene, pyridinium tribromide, meso-stilbene
dibromide, potassium hydroxide, triethylene glycol,
diphenylacetylene, ethanol
Mole Table Drawn immediately beneath the Overall Reaction, the Mole Table is used to calcu late the theoretical yield of your product using stoich iometry. All calculations are to be shown in the "Calculations" section. Each column refers to the structure drawn above it. Please cite the source of Mole Table information stated in the Mole Table - refer to the example below for format. As...
please help with filling out this table and answering 8
questions
Data Table Br H CH2CH3OH N-H Bry Chemicals H (E)-Stilbene Ethanol Pyridinium tribromide CsH.Br3N Stilbene Dibromide C14H12Br2 Molecular Formula C14H12 CHO Molecular Weight 180.25 g/mol 46.07 g/mol 319.82 g/mol 340.06 g/mol Physical Properties White solid Clear liquid White solid White solid Melting Point 122-124 °C N/A 127-133 °C 241-243 °C Amount needed 0.25 g 10 mL 0.5 g Mole needed 1.39 mmol 1.56 mmol Amount Used Moles Used Amount...
1. Most of the class will be brominating trans-stilbene (part B) and the rest cis-stilbene (part A). For this assignment write a detailed procedure in your lab notebook for Part B. Upload a picture/scanned copy (5 pts). Tip: If you write the procedure down the left half of the page, you can leave space to record your measurements/observations down the right side of the page. If you end up using cis-stilbene in the experimental there will only be a few...
2. Your lab manual proposes 3 possible mechanisms for bromination. During this lab, you will determine which iroduct(s) formed during the bromination of stilbene. (9 pts) a. Four possible products from the bromination of trans-stilbene are shown below. Label the chiral centers as Sor R. Ph Br Br H iph H Phil Br Ph Ph Br B. HINH Philiph Phí By HP b. The enantiomer of structure A is: c. The enantiomer of structure Dis: d. Ust the letters corresponding...
here is the procedure if needed
EXPERIMENT 8: BROMINATION OF TRANS-STILBENE glacial acetic acid Objective: Execute first step of two-step sequence to transform an alkene into an alkyne via a dihalide intermediate and use infrared spectroscopy to identify functional groups PRELAB NOTEBOOK: In the laboratory notebook, write the overall experimental objective, chemical equation(s), reaction mechanism (consider all possible stereoisomers), draw a diagram or outline of the procedural steps, and complete the chemical safety table for all chemicals. 1. Why is...
Postlab Questions Answer the following questions on a separate sheet or in your lab notebook. Make sure that the copy page is readable! D) Calculate the percentage yield for both reactions. Show all calculations. 2) What is the color of the reaction at the beginning of reaction? What causes the color? 3) Why do you dissolve maleic acid in diethyl ether and fumaric acid in water? 4) Give the complete reaction mechanisms for the formation of meso and racemic 2,3-...
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