BackAcetylide ions also add to ethylene oxide much like Grignard and organolithium reagents. Predict the products obtained by adding the following acetylide ions to ethylene oxide, followed by a dilute acid workup.
(a) HC≡C:–
(b) CH3CH2–C≡C:–
Addition of 1-bromobut-2-ene to magnesium metal in dry ether results in formation of a Grignard reagent. Addition of water to this Grignard reagent gives a mixture of but-1-ene and but-2-ene (cis and trans). When the Grignard reagent is made using 3-bromobut-1-ene, addition of water produces exactly the same mixture of products in the same ratios. Explain this curious result
How could the following compounds be prepared, using cyclohexene as a starting material?
d.
Often, compounds can be synthesized by more than one method. Show how this 3° alcohol can be made from the following:
(a) two different ketones
List three different sets of reagents (each set consisting of a carbonyl compound and a Grignard reagent) that could be used to prepare each of the following tertiary alcohols:
a.
Show how you would synthesize the following:
a. 2-phenylethanol by the addition of formaldehyde to a suitable Grignard reagent
Predict the products of the following reactions.
(d) product of (c) + cyclopentylmagnesium bromide, then acidic hydrolysis
A chemist attempted the reaction below, one we introduce in Chapter 17, expecting the reaction between a strong nucleophile and a ketone in water to give an alkoxide product.
(a) Why did the reaction fail?
(b) How could the reaction conditions be changed to give a successful reaction?
Predict the products of the following reactions.
(a) allyl bromide + cyclohexyl magnesium bromide
In lieu of quenching the product of Grignard addition to a carbonyl with acid, alkyl halides can be added directly to generate ether products. Predict the product and show the mechanism of this process.
Two of the methods for converting alkyl halides to carboxylic acids are covered in Sections 20-8B and 20-8C. One is formation of a Grignard reagent followed by addition of carbon dioxide and then dilute acid. The other is substitution by cyanide ion, followed by hydrolysis of the resulting nitrile. For each of the following conversions, decide whether either or both of these methods would work, and explain why. Show the reactions you would use.
(e)
(f)
Point out the flaws in the following incorrect Grignard syntheses.
(b)
Which of the following alkyl halides could be successfully used to form a Grignard reagent?
Show two ways you could synthesize each of the following secondary alcohol by adding an appropriate Grignard reagent to an aldehyde.
(c)
Predict the product of the following epoxide addition reactions.
(b)