Reactions of the Hydroxy Group

Diazomethane, CH Nj, is an explosive, yellow gas which is a source of methylene. CH, and is an efficient methylating agent. 

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This section treats the synthetic reactions of phenols leading to C—O bond formation at the hydroxy group and C—C bond formation at the aromatic nuclei. Reactions similar to those of aliphatic alcohols, aromatic hydrocarbons or anisole are in general excluded. Oxidation reactions and replacement reactions of the hydroxy group are treated in other chapters of this book. 

IV. REACTIONS OF THE HYDROXY GROUPS IN CALIXPHENOLS A. Complete Conversions... 

Scheme 5. Possible follow-up reactions of the hydroxy group of chiral cyanohydrins...

Intramolecular reaction of the hydroxy group with the carboxylic acid function gives the cyclic ester (lactone) product shown above. 

For well-controlled arm number of the star polymers, an efficient approach is the use of multifunctional initiators [157,158]. For instance, the four-armed initiator, NLI-1, which was prepared by the condensation reaction of the hydroxy groups in C(CH20CH2CH2CH20H)4 with a-bromoisobutyric acid, was used in the ATRP of (2,2-dimethyl-l,3-dioxoIane-4-yl)methyl acrylate (DMDMA) with CuBr/bpy as catalyst. After isolation from the polymerization system, four-armed poly(DMDMA)s, such as NLI-2 with Mw/Mn = 1.28—1.41 were obtained, and used in the successive ATRP of MMA, giving star-block copolymers NLB-3. It is known that the cycloacetal ring is unstable in acidic conditions, so the hydrolysis of the block copolymer NLB-3 was accomplished in a 1N HCl aqueous solution to give the amphiphilic star-block copolymer structure NLB-4 as shown in Scheme 3.37 [159]. 

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