Concept (explain why this is so..)

Problem # 1287

Rank each set of compounds in order of decreasing boiling point (1 = highest boiling point):

a) ethane, n-octane, n-pentane

b) n-butane, 1-butanol, 1-chlorobutane.

c) n-octane, 2-methylheptane, 2,5-dimethylhexane


(Note that the n- prefix before an alkane just means that it's one chain, without any branching.)

Problem # 1286

For the molecule shown below, indicate the hybridization (sp3, sp2, sp, etc.) of atoms A through H, and the bond angles of X, Y, and Z.

Problem # 1281

Allylic and benzylic halides tend to undergo both SN1 and SN2 substitution reactions at a faster rate than their alkyl counterparts.

For example, both allyl chloride and benzyl chloride undergo SN2 reaction at a faster rate than propyl chloride. 

The same holds true for SN1 reactions: a 2° allyl or benzyl halide undergoes SN1 reaction faster than a 2° alkyl halide. Explain.

Problem # 1280

The structure of 2-methylbutane is shown below.

a) Draw the structures of all possible monochloro products resulting from the free-radical chlorination of 2-methylbutane.

b) Based on statistics alone, what do you expect the major product to be? Is this the same structure as the expected major product? Explain.

c) How would the relative yield of the products differ if bromine was used instead of chlorine?

Problem # 755

The nitrosyl cation is shown below. Also shown are several proposed resonance arrows, only one of which is correct.

Draw the resonance forms that would follow from each set of arrows, and include formal charges. Which one is the correct resonance form? Explain your reasoning.

Problem # 754

Show how each amine can be prepared from a carbonyl and an amine via reductive amination.

Problem # 753

Rank the amines W through Z below in order of decreasing basicity (1 = most basic). Explain your reasoning.

Problem # 752

Rank the amines A through D below in order of decreasing basicity (1 = most basic). Explain your reasoning.

Problem # 748

Alpha bromination is usually carried out under acidic conditions via the enol intermediate. 

Alpha bromination is uncontrollable under basic conditions, which goes through the enolate intermediate. Let's explore why.



a) Rank each carbonyl below in order of decreasing alpha-proton acidity (1= most acidic). Explain.

b) based on a), why does the reaction below lead to polyhalogenation?

Problem # 745

The molecule below has five different types of hydrogens (A through E). Rank each in order of decreasing acidity.

(1 = most acidic). Explain your reasoning.