Organic Chemistry
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Assuming the following equilibrium reaction occurs, identify the direction of the reaction that is more favored.
Determine the number of 𝝅 electrons present in the conjugated systems of the given compound below.
Rationalize why conjugated compounds, such as the one formed in a ninhydrin reaction, are light-colored.
Determine the isoprene units in the given terpenes. [Note: Cross-linked or ring-containing terpenes can exhibit linkages beyond the C1 and C4 of their isoprene units.]
Determine the isoprene units of the given terpenes.
What are the isoprene units in the given terpene? Take note that in terpenes with cross-links or rings, linkages between carbon atoms other than C1 and C4 of the isoprene unit are possible.
How many molecular orbitals (MOs) does 1,3,5-hexatriene have?
For the molecular orbitals (MOs) of 1,3,5-hexatriene, determine the MOs that are symmetrical and antisymmetrical.
For the molecular orbitals (MOs) of 1,3,5-hexatriene, determine which MO, in the ground state, is the HOMO and is the LUMO.
For the molecular orbitals (MOs) of 1,3,5-hexatriene, determine which MO, in the excited state, is the HOMO and is the LUMO.
For the molecular orbitals of 1,3,5-hexatriene, determine how the HOMO and LUMO and the symmetric and antisymmetric orbitals are related.
For the molecular orbitals of 1,3,5-hexatriene, determine the number of nodes in the highest-energy MO of the given molecule between the nuclei.
Determine the number of linear dienes consistent with the formula C7H12. Do not include stereoisomers. How many of these are conjugated dienes?
Identify each of the given diene and polyene as cumulated, conjugated, or isolated.
Under basic conditions, compound II will form a conjugate system while compound I will not. Give a possible explanation and provide the mechanism that shows the formation of the conjugated system in compound II.
Thymolphthalein is an acid-base indicator that appears colorless in solutions with a pH below 9.4 and blue in solutions with a pH above 10.6. Explain why the protonated form of thymolphthalein is colorless, while the deprotonated form is colored.
Assess if the given structure is likely to exhibit color. If you anticipate it to be colored, highlight the atoms involved in extended conjugation.
Assess if the following structure is likely to exhibit color. If you anticipate it to be colored, highlight the atoms involved in extended conjugation.
Assess if the following structure is likely to exhibit color. If you predict it to be colored, highlight the atoms involved in extended conjugation.
a. Determine the number of molecular orbitals present in 1,3,5-heptatriene and the designation of its HOMO (such as Ψ1, Ψ2).
b. How many nodes are there in its highest energy molecular orbital?
Explain why the diagram below does not accurately represent the molecular orbital ψ2 of hexa−1,3,5−triene.
Consider the following ψ4 molecular orbital for deca-1,3,5,7,9-pentaene:
What is its ψ5?
To create four pi bonds, octa−1,3,5,7−tetraene uses eight p orbitals that contain one electron each. Determine the total number of molecular orbitals made by the eight p orbitals.
Identify the isoprene units in the given terpenes. (Note: Terpenes with cross-links or rings can form linkages between carbon atoms other than C1 and C4 of the isoprene unit.)
Specify the isoprene units in nerolidol. Note: linkages can be formed than other than just 1→4 linkages.
Box the isoprene units in carvone. Note: linkages can be formed other than just 1→4 linkages.
Mark the isoprene units in squalene. Note: linkages can be formed other than just 1→4 linkages.
The structure of retinol (vitamin A1) is shown below.
Mark the isoprene units that were used to make retinol.
Identify the isoprene units in the following terpenoid. Linkages can be formed between more than just C-1 and C-4 of isoprene when the terpene or terpenoid is ring-containing.
Determine the isoprene units in the following terpene/terpenoid. Linkages can be formed between more than just C-1 and C-4 of isoprene when the terpene/terpenoid is ring-containing.
Myrcene which is a monoterpene and a fragrant oily liquid, can isomerize into limonene, ocimene, and alloocimene. Suggest an acid-catalyzed mechanism by which limonene could be produced from myrcene.
Determine whether the diene given below is in the s-cis or s-trans conformation. Draw the s-cis conformation of the diene if it is in the s-trans conformation.
Specify whether the diene shown below is in the s-cis or s-trans conformation. Draw the s-cis conformation of the diene in case it is in the s-trans conformation.
Which of the following is true when one of the ions in the given image is purple at pH 7; whereas the other is blue?
Predict whether each structure shown below is likely to be colored organic compounds or not. Show the extended conjugation for structures that you predict to be colored by marking the series of continuous sp2 hybridized atoms.
How can you distinguish between the following compounds using UV spectroscopy?
A sample is prepared by dissolving 1.20 mg of a compound of molecular weight 180 in 10.0 mL of ethanol. The sample solution is poured into a 1.00-cm UV cell and the UV spectrum is taken. Determine the molar absorptivity of the sample if λmax = 250 nm, and the maximum absorbance at 250 nm is 0.630.
Two different types of absorptions are observed in the UV spectrum of 3-methyl-1-phenylbut-2-en-1-ol: a weak absorption at 220 nm and a more intense absorption at 258 nm.When this compound is reacted with dilute sulfuric acid, an isomeric product with a weak absorption at 290 nm and a more intense absorption at 250 nm is obtained. Propose a plausible mechanism for the reaction described above. You should include the structure of the reaction product in your proposed mechanism.
An unknown compound in a 3.0 x 10-4 M hexane solution shows the absorption of 0.30 at 230 nm in a 1 cm cell. Calculate its molar absorptivity at this wavelength.
The following compounds have very different colors in powdered form. What would be the difference in the colors of the compounds in a highly acidic solution?
The acid-base indicator, Bromophenol blue, is yellow in pH below 3.0 and blue in pH above 4.6. Explain the color change.
Consider the linear dienes with a molecular formula C7H14 (disregard stereoisomers),
i. How many are isolated dienes?
ii. How many are cumulated dienes?
