Pendant chains, synthesis

As an example, bulk modification by the organic reaction of unsaturated PHA with sodium permanganate resulted in the incorporation of dihydroxyl or carboxyl functional groups [106]. Due to the steric hindrance of the isotactic pendant chains, complete conversion could not be obtained. However, the solubility of the modified polymers was altered in such a way that they were now completely soluble in acetone/water and water/bicarbonate mixtures, respectively [106]. Solubility can play an important role in certain applications, for instance in hydrogels. Considering the biosynthetic pathways, the dihydroxyl or carboxyl functional groups are very difficult to incorporate by microbial synthesis and therefore organic chemistry actually has an added value to biochemistry. 

Sallas, F, Nishimura, S-I, Chemo-enzymatic synthesis of glycopolymers and sequential glycopeptides hearing lactosamine and sialyl Lewis unit pendant chains, J. Chem. Soc. Perkin Trans. 1, 2091-2103, 2000. 

As fluorinated poly(alkylacrylates) have proved to be highly soluble in compressed CO2, they present themselves as possible components in the stabilization of heterogeneous reaction systems in CO2. Indeed, there has been considerable effort in the development and synthesis of polymeric emulsifiers for lipophilic materials and stabilizers for hydrocarbon polymer dispersions in CO2. DeSimone and coworkers demonstrated the feasibility of using fluorinated alkyl acrylate homopolymers, such as PFOA, as efficient amphiphiles, owing to the lipophilic acrylate backbone and the C02-philic fluorinated pendant chains [35, 36]. As was described earlier, these fluorinated alkyl acrylates are readily synthesized homogeneously in CO2. The solution properties and phase behavior of PFOA in compressed CO2 have been thoroughly examined and reported elsewhere [37-39]. 

L. Andersson, J. Davies, R. Duncan, P. Ferruti, J. Ford, S. Kneller, R. Mendichi, G. Pasut, O. Schiavon, C. Summerford, A. Tirk, F. M. Veronese, V. Vincenzi and G. R Wu, Poly(ethylene glycol)-poly(ester-carbonate) block copolymers carrying PEG-peptidyl-doxorubicin pendant side chains Synthesis and evaluation as anticancer conjugates. Biomacromolecules, 6,914-926 (2005). 

Columnar liquid crystals are derived from disc- or plate-like molecules. For the most part, these compounds possess a core unit with pendant chains (usually 4,6, or 8). Synthetically two main options of synthesis are pursued (see Scheme 2) ... 

Cyclization of the two pendant alkyl side chains on barbiturates to form a spiran is consistent with sedative-hypnotic activity. The synthesis of this most complex barbiturate starts by alkylation of ethyl acetoacetate with 2-chloropentan-3-one to give 152. Hydrolysis and decarboxylation under acidic conditions gives the diketone, 153. This intermediate is then reduced to the diol (154), and that is converted to the dibromide (155) by means of hydrogen bromide. Double Internal alkylation of ethyl... 

Ebdon and coworkers22 "232 have reported telechelic synthesis by a process that involves copolymerizing butadiene or acetylene derivatives to form polymers with internal unsaturation. Ozonolysis of these polymers yields di-end functional polymers. The a,o>dicarboxy1ic acid telechelic was prepared from poly(S-s tot-B) (Scheme 7.19). Precautions were necessary to stop degradation of the PS chains during ozonolysis. 28 The presence of pendant carboxylic acid groups, formed by ozonolysis of 1,2-diene units, was not reported. 

Polymeric polyolefins, such as polybutadiene, secondary amines, and synthesis gas, are reacted in the presence of a catalyst system comprising a ruthenium-containing compound, a rhodium-containing compound, a steri-cally hindered phosphine, and a solvent [1191]. Preferred polybutadiene feedstocks are those with a predominance of main chain, rather than pendant olefin groups and in particular, those polymers containing both the 1,2-polybutadiene and 1,4-polybutadiene units. These polymers of high amine content are useful as down-hole corrosion inhibitors. 

Andrianov and Zhdanov have developed a method for the synthesis of polymers containing heterochain and carbon-chain units by free-radical copolymerization of metal-containing polyorganosiloxanes bearing a pendant vinyl group with vinyl monomers. The copolymers thus obtained display increased thermal stability and can be used for the production of laminated plastics, adhesives and other valuable materials 53),... 

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