Glycol groups, activation

One instance where correlation with cuprammonium data appears possible is the reaction between adjacent cis glycol groups and acetone to form isopropylidene derivatives. Although data on the kinetics and equilibria of isopropylidene formation are too meager to prove that reactivity with acetone parallels reactivity with cuprammonium, isolated observations support such a supposition. Knauf, Hann, and Hudson12 have noted the ease of formation of the acetone derivatives of D-mannosan, and this is one of the substances most reactive toward cuprammonium.6 Tipson13 has noted that the optically active 2,3-butanediols react with acetone more readily than the meso form, and this is the order in which these substances react with cuprammonium.14... 

M.K. Calabretta, A. Kumar, A.M. McDermott, C. Cai, Antibacterial activities of poly(amidoamine) dendrimers terminated with amino and poly(ethylene glycol) groups. Biomacromolecules 8 (2007) 1807-1811. 

It should be emphasized that the spacer bearing support modified in this way is indeed uniformly functionalized. The tertiary glycolic group was found entirely inert to the reaction conditions of the Merrifield synthesis, if low concentrations of trifluoroacetic acid (< 10%, in dichloromethane) are used in the deprotection procedures [81]. The subsequent elimination of water from the remaining tertiary alcoholic function of the glycolic handle which leads to the activation of the C-termini of peptides synthetized on this support, will be described in Sect. 3.5.3.1. 

In practice, 1—10 mol % of catalyst are used most of the time. Regeneration of the catalyst is often possible if deemed necessary. Some authors have advocated systems in which the catalyst is bound to a polymer matrix (triphase-catalysis). Here separation and generation of the catalyst is easy, but swelling, mixing, and diffusion problems are not always easy to solve. Furthermore, triphase-catalyst decomposition is a serious problem unless the active groups are crowns or poly(ethylene glycol)s. Commercial anion exchange resins are not useful as PT catalysts in many cases. 

Specialty Epoxy Resins. In addition to bisphenol, other polyols such as aUphatic glycols and novolaks are used to produce specialty resins. Epoxy resins may also include compounds based on aUphatic, cycloaUphatic, aromatic, and heterocycHc backbones. Glycidylation of active hydrogen-containing stmctures with epichlorohydrin and epoxidation of olefins with peracetic acid remain the important commercial procedures for introducing the oxirane group into various precursors of epoxy resins. 

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