Amines sulfonic acid, polymer-supported

In an opposite manner to bases such as 1 and 2 in terms of reactivity, polymer-supported tosyl chloride equivalent 14 is able to capture alcohols as polymer-bound sulfonates 15, which are released as secondary amines, sulfides and alkylated imidazoles with primary amines, thiols and imidazoles as nucleophiles in a substitution process (Scheme 6) [24]. This technique has further been extended for the preparation of tertiary amines [25] and esters [26]. Excess of amine was scavenged by polymer-supported isocyanate 16 [27, 28] while excess of carboxylic acid was removed by treatment with aminomethylated polystyrene 17. 

TsOH, THF, CH2CI2,5 min. This method was developed for solid-phase peptide synthesis as a safe large-scale alternative to the use of TFA, which is expensive, corrosive, and a waste problem on a large scale. The reaction is accelerated with microwave irradiation. Polymer-supported sulfonic acids such as Am-berlyst 15 effectively cleave the BOC group and leave it loaded on the resin. Washing with NH4OH releases the free amine from the resin in pure form. ... 

Obrecht described the reaction of resin-bound thiouronium salt 111 vrith oxophe-nylbutynoic acid tert-butyl ester. Cleavage from the support was effected by S-oxidation to the sulfone followed by displacement vrith an amine [132]. The thiouronium salt pathway is illustrated in Scheme 26. Later, Masquelin et al. developed a condensation of resin-bound thiouronium salts with methylenemalononitriles to provide polymer-bound alkylthiopyrimidines 110 [133]. Pyrimidine derivatives 112... 

The most widely used chemically modified PPO in the development of thin film composite membranes is sulfonated polyphenylene oxide (SPPO). The polymer in the acid form as well as salt form has been used by Bikson to produce multilayer composite membranes. These types of membranes have been described to have at least two chemically distinct layers deposited on a porous substrate in a single coating step process. The outer layer forms a protective defect-sealing surface whereas the inner layer is the selective SPPO layer. This layer is adjacent to the porous support membrane. The two top layers are formed simultaneously on top of porous polysulfone support hollow fibers. A coating solution of SPPO in the lithium salt form (SPPO-Li ) and amine functional silicone fluid was coated on top of the polysulfone fibers. These coated fibers were used to construct a hollow fiber separator permeator. 

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