Carbons 1 and 4 of 1,3-cyclopentadiene are equivalent and give the same carbocation on protonation. Likewise, carbons 2 and 3 are equivalent. Write the structure of the carbocation formed by protonation of C-2 or C-3 to verify that it is not allylic and therefore not as stable as the one formed by protonation of C-1 or C-4.

Draw the structure for (E)-3,4-dimethyl-2-hexene.  SHOW STEREOCHEMISTRY.

1)Chemistry students are taking an experimental course in organic chemistry at a public university. During an experiment involving conjugated dienes, some doubts arose when discussing the results obtained so far: (a) A student obtained two products from the reaction of 1,3-cyclohexadiene with Br2. His lab partner was surprised to get only one product from the reaction of 1,3 - cyclohexadiene with HBr. Explain these distinct results.   (b) One student, seeing the discussion of colleagues, commented that she obtained two distinct products when reacting 1,3,5-hexatriene with HBr, with different yields just by changing the reaction temperature. Explain the results she obtained using reaction mechanism and based on kinetic and thermodynamic control involving conjugated dienes.

Perform a conformational analysis of 3-bromo-2-methylpentane using Newman projections viewed through the C3-C4 bond (C3 in the front, C4 in the back). Write the relevant conformations in 60° increments, indicate whether they are eclipsed or staggered, gauche, anti, or syn, and plot their Br relative potential energy. As you plot their relative potential energy, consider the isopropyl group on carbon 3 to be bulkier than the bromo group on carbon 3. 5.

Consider the reaction between (1S,3S)‑1‑chloro‑3‑methylcyclopentane and methanethiol in the presence of sodium hydroxide. (a) Draw the organic product and clearly indicate stereochemistry by showing the hydrogen on the chirality centers and using wedge and dash bonds. (b) Then analyze the stereochemistry of the product. racemic chiral achiral (1R, 3S) (1R, 3R) (1S, 3S)

Draw cis and trans 1,2-dichloroethylene (C2H2Cl2) and predict their relative energie