7. Substitution Reactions

Order the following molecules on the basis of their nucleophilic strength using the pKₐ values of their conjugate acids.

Suggest a reagent to carry out each of the following conversions to an alcohol.

(c)

Predict the product(s) of the following reactions.

(f)

Predict the product(s) of the following reactions.

(g)

When trans-4-bromocyclohexanol is treated with base, an intramolecular substitution reaction occurs to give a cyclic ether. This product does not form when cis-4-bromocyclohexanol is reacted under the same conditions. Explain these observations.

Which of the following reactions take place more rapidly when the concentration of the nucleophile is increased?

Starting with (R)-1-deuterio-1-propanol, how could you prepare

c. (R)-1-deuterio-1-methoxypropane?

Even with an excess of cyanide, only one equivalent will react with the following dibromoalkane. To which carbon will the cyanide add? Predict the product and explain your choice.

Suggest a mechanism for the following reactions.

(a) Substitution:

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (i) SOCl₂ ; (ii) PBr₃ ; (iii) SOCl₂ , NEt₃ (iv) 1. TsCl, Et₃N 2. NaCN; (v) 1. TsCl, Et₃N 2. NaOt-Bu (vi) H₂SO₄ (vii) HCl; (viii) HBr; (ix) PCC; (x) H₂CrO₄ , H₂O (xi) HOCl, H₂O (xii) HIO₄ If no reaction occurs, write 'no reaction.'

(o)

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (iii) SOCl₂ , NEt₃ (iv) 1. TsCl, Et₃N 2. NaCN; If no reaction occurs, write 'no reaction.'

(o)

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (i) SOCl₂ ; (ii) PBr₃. If no reaction occurs, write 'no reaction.'

(k)

Explain how 1-butanol can be converted into the following compounds:

a.

Explain how 1-butanol can be converted into the following compounds:

b.

cis-4-Bromocyclohexanol and trans-4-bromocyclohexanol form the same elimination product but a different substitution product when they react with HO⁻.

b. Explain, by showing the mechanisms, why different substitution products are obtained.