Concept explainers
Interpretation:
When previtamin D2 (which is identical to previtamin D3, p. 1478, except for the R-group) is isolated and irradiated, ergosterol is obtained along with a stereoisomer, lumisterol. The origin of lumisterol is to be explained mechanistically.
Concept introduction:
Electrocyclic reactions are a pericyclic reaction which occur intramolecularly. These reactions will result in the formation of ring compounds under the influence of heat or light. Notably, in this process one new sigma bond is formed and one old π-bond is consumed. Intriguingly, the reverse ring opening electrocyclic reaction can also be possible to occur under the same reaction mechanism but in reverse manner. In phase orbital overlap results in symmetry allowed electrocyclic reactions. Selection rules of electrocyclic reactions are;
No. of electrons | Activation mode | Stereochemistry of rotation |
4n | Thermal Photochemical |
Con Dis |
4n + 2 | Thermal Photochemical |
Dis Con |
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Chapter 28 Solutions
EBK ORGANIC CHEMISTRY STUDY GUIDE AND S
- Explanation O Conjugated Pi Systems Deducing the reactants of a Diels-Alder reaction Can the molecule on the right-hand side of this organic reaction be made in good yield from no more than two reactants, in one step, by moderately heating the reactants? ? Δ If your answer is yes, then draw the reactant or reactants in the drawing area below. You can draw the reactants in any arrangement you like. • If your answer is no, check the box under the drawing area instead. Click and drag to start drawing a structure. Xarrow_forwardDiels Alder Cycloaddition: Focus on regiochemistry (problems E-F) –> match + of thedienophile and - of the diene while also considering stereochemistry (endo).arrow_forwardHELP! URGENT! PLEASE RESOND ASAP!arrow_forward
- Question 4 Determine the rate order and rate constant for sucrose hydrolysis. Time (hours) [C6H12O6] 0 0.501 0.500 0.451 1.00 0.404 1.50 0.363 3.00 0.267 First-order, k = 0.210 hour 1 First-order, k = 0.0912 hour 1 O Second-order, k = 0.590 M1 hour 1 O Zero-order, k = 0.0770 M/hour O Zero-order, k = 0.4896 M/hour O Second-order, k = 1.93 M-1-hour 1 10 ptsarrow_forwardDetermine the rate order and rate constant for sucrose hydrolysis. Time (hours) [C6H12O6] 0 0.501 0.500 0.451 1.00 0.404 1.50 0.363 3.00 0.267arrow_forwardDraw the products of the reaction shown below. Use wedge and dash bonds to indicate stereochemistry. Ignore inorganic byproducts. OSO4 (cat) (CH3)3COOH Select to Draw ઘarrow_forward
- Calculate the reaction rate for selenious acid, H2SeO3, if 0.1150 M I-1 decreases to 0.0770 M in 12.0 minutes. H2SeO3(aq) + 6I-1(aq) + 4H+1(aq) ⟶ Se(s) + 2I3-1(aq) + 3H2O(l)arrow_forwardProblem 5-31 Which of the following objects are chiral? (a) A basketball (d) A golf club (b) A fork (c) A wine glass (e) A spiral staircase (f) A snowflake Problem 5-32 Which of the following compounds are chiral? Draw them, and label the chirality centers. (a) 2,4-Dimethylheptane (b) 5-Ethyl-3,3-dimethylheptane (c) cis-1,4-Dichlorocyclohexane Problem 5-33 Draw chiral molecules that meet the following descriptions: (a) A chloroalkane, C5H11Cl (c) An alkene, C6H12 (b) An alcohol, C6H140 (d) An alkane, C8H18 Problem 5-36 Erythronolide B is the biological precursor of erythromycin, a broad-spectrum antibiotic. How H3C CH3 many chirality centers does erythronolide B have? OH Identify them. H3C -CH3 OH Erythronolide B H3C. H3C. OH OH CH3arrow_forwardPLEASE HELP! URGENT! PLEASE RESPOND!arrow_forward
- 2. Propose a mechanism for this reaction. ہلی سے ملی N H (excess)arrow_forwardSteps and explanationn please.arrow_forwardProblem 5-48 Assign R or S configurations to the chirality centers in ascorbic acid (vitamin C). OH H OH HO CH2OH Ascorbic acid O H Problem 5-49 Assign R or S stereochemistry to the chirality centers in the following Newman projections: H Cl H CH3 H3C. OH H3C (a) H H H3C (b) CH3 H Problem 5-52 Draw the meso form of each of the following molecules, and indicate the plane of symmetry in each: OH OH (a) CH3CHCH2CH2CHCH3 CH3 H3C. -OH (c) H3C CH3 (b) Problem 5-66 Assign R or S configurations to the chiral centers in cephalexin, trade-named Keflex, the most widely prescribed antibiotic in the United States. H2N H IHH S Cephalexin N. CH3 CO₂Harrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning
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