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QUESTION 4 Based on the image of a TLC plate below, how far (in cm) did...
6) Plate A, below, represents the TLC chromatogram of a compound run in hexanes. The same...
6) Plate A, below, represents the TLC chromatogram of a compound run in hexanes. The same compound was then spotted on a large TLC plate and again run in hexanes Which TLC plate, B, C, or D, correctly represents how far the compound would run on the longer plate? solvent front solvent - front plate A plate B plate plate D
4. Consider the following silica gel TLC plac or compounds A, B, and hexines: developed in...
4. Consider the following silica gel TLC plac or compounds A, B, and hexines: developed in Fo-o- og a) Determine the Rr values of compounds A, B, and C run on a silica gel TLC plate using hexanes as the solvent b) Which compound, A, B, or C. is the most polar? values if you used acetone instead c) What would you expect to happen to the of hexanes as the eluting solvent? 5) Consider a sample that is a...
Possible Quiz Questions 1 What two methods of visualizing spots on a TLC plate will you...
Possible Quiz Questions 1 What two methods of visualizing spots on a TLC plate will you use in this Give two reasons why would you predict that the elution solvents (hexanes or acetate) would not be visible under UV visualization? week's lab? ethyl 2. Define R 3. Calculate the R of the spot on the following TLC plate. 4. Which compound in each pair is predicted to have the higher Ri? a. CH3CH2CH2CH2OH and CH3CH2CH2CH28r b. CH3CH2CH2CH2OH and CH3CH2CH2CH2CH2CH2CH3 c....
3. If the TLC plate development had stopped before the solvent front reached the top of...
3. If the TLC plate development had stopped before the solvent front reached the top of the TLC plate (i.e. maybe it reached the middle of the TLC plate when it was stopped, instead): a) Would the Rf values have been affected? If so, how? If not, why not? Give a numerical example to support your answer. b) Would the size of the spots have been affected? If so, how? If not, why not? (Hint: think about the diffusion of...
I need help with my pre and post lab questions. The three compounds below were spotted...
I need help with my pre and post lab questions.
The three compounds below were spotted on a TLC plate and developed to give the TLC plate shown. Which compound corresponds to which spot? Calculate the Rf value for spot B in the TLC plate shown above. When using polarity to determine the relative rates at which organic compounds travel up the TLC plate, we are considering compounds of similar molecular weight. It should also be noted that Rf values...
Please help 2. Consider the TLC plate shown below that was done on silica gel using...
Please help
2. Consider the TLC plate shown below that was done on silica gel using a solvent mixture of 4:1 hexane/EtoAc as the eluent. 4:1 Hexane:EtOAC marked solvent front Spot B Spot A A origin (a) Which of the two organic compounds labeled A and B is less polar? (b) Calculate the Rf value of compound B. (c) How would the following changes affect the Rf values of A and B? i. Change to a more polar solvent mixture...
A student monitored the reaction progress of the reduction of 4-Nitrobenzaldehyde to 4-Nitrobenzyl alcohol using TLC....
A student monitored the reaction progress of the reduction of
4-Nitrobenzaldehyde to 4-Nitrobenzyl alcohol using TLC. 30% ethyl
acetate in petroleum ether was used as the elution solvent. TLC
plates available in the laboratory were coated with the common
absorbent silica gel (SiO2.xH2O) which
contains polar hydroxyl (OH-) groups.
c. The crude product moves slower
than the starting material with the mobile
phase in the TLC plate. Briefly
explain a possible reason for the
observation based on the chemical
structures...
CHEM 2010 LAB TLC 4 PRELAB WORK 1. How would you change your technique for application...
CHEM 2010 LAB TLC 4 PRELAB WORK 1. How would you change your technique for application or solvent system if each of these issues was observed: a.Large spot that trails up plate b.Barely visible spot C. Spot barely moves even with solvent near top of plate d. Both compounds of mixture travel with solvent front to top with little to no separation.
4) sketch what a developed and resolved TLC plate of a mixture of benzil, benzoin and...
4) sketch what a developed and resolved TLC plate of a mixture of benzil, benzoin and hydrobenzoin might look like. Discuss the relative Rf values on your sketched plate 5) In the reduction of benzil with sodium borohydride, 3 compounds are possible: meso-hydrobenzoin, racemic-hydrobenzoin and racemic-benzoin (resulting from incomplete reduction of benzil). Discuss how you determined (or will go about determining) which of these products was produced. Discuss evidence from melting points, TLC and IR spectra.
Referring back to question 5 above, in the TLC plate on the left the eluting mobile...
Referring back to question 5 above, in the TLC plate on the left the eluting mobile phase solvent was ethyl acetate, in the plate on the right it was 97% ethyl acetate and 3% methanol. Explain why the Rf values in the plate on the right are larger than those in the plate on the left. Your explanation must be in the terms of intermolecular forces, you are not allowed to only use the word "polarity". There are THREE dynamical...
6) Plate A, below, represents the TLC chromatogram of a compound run in hexanes. The same compound was then spotted on a large TLC plate and again run in hexanes Which TLC plate, B, C, or D, correctly represents how far the compound would run on the longer plate? solvent front solvent - front plate A plate B plate plate D
4. Consider the following silica gel TLC plac or compounds A, B, and hexines: developed in Fo-o- og a) Determine the Rr values of compounds A, B, and C run on a silica gel TLC plate using hexanes as the solvent b) Which compound, A, B, or C. is the most polar? values if you used acetone instead c) What would you expect to happen to the of hexanes as the eluting solvent? 5) Consider a sample that is a...
Possible Quiz Questions 1 What two methods of visualizing spots on a TLC plate will you use in this Give two reasons why would you predict that the elution solvents (hexanes or acetate) would not be visible under UV visualization? week's lab? ethyl 2. Define R 3. Calculate the R of the spot on the following TLC plate. 4. Which compound in each pair is predicted to have the higher Ri? a. CH3CH2CH2CH2OH and CH3CH2CH2CH28r b. CH3CH2CH2CH2OH and CH3CH2CH2CH2CH2CH2CH3 c....
I need help with my pre and post lab questions.
The three compounds below were spotted on a TLC plate and developed to give the TLC plate shown. Which compound corresponds to which spot? Calculate the Rf value for spot B in the TLC plate shown above. When using polarity to determine the relative rates at which organic compounds travel up the TLC plate, we are considering compounds of similar molecular weight. It should also be noted that Rf values...
Please help
2. Consider the TLC plate shown below that was done on silica gel using a solvent mixture of 4:1 hexane/EtoAc as the eluent. 4:1 Hexane:EtOAC marked solvent front Spot B Spot A A origin (a) Which of the two organic compounds labeled A and B is less polar? (b) Calculate the Rf value of compound B. (c) How would the following changes affect the Rf values of A and B? i. Change to a more polar solvent mixture...
A student monitored the reaction progress of the reduction of
4-Nitrobenzaldehyde to 4-Nitrobenzyl alcohol using TLC. 30% ethyl
acetate in petroleum ether was used as the elution solvent. TLC
plates available in the laboratory were coated with the common
absorbent silica gel (SiO2.xH2O) which
contains polar hydroxyl (OH-) groups.
c. The crude product moves slower
than the starting material with the mobile
phase in the TLC plate. Briefly
explain a possible reason for the
observation based on the chemical
structures...
Referring back to question 5 above, in the TLC plate on the left the eluting mobile phase solvent was ethyl acetate, in the plate on the right it was 97% ethyl acetate and 3% methanol. Explain why the Rf values in the plate on the right are larger than those in the plate on the left. Your explanation must be in the terms of intermolecular forces, you are not allowed to only use the word "polarity". There are THREE dynamical...
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