Poly rearrangement reaction

A polymeric pinacol,poly[3-methyl-2-(4-vinylphenyl)-2,3-butanediol],has been prepared by radical polymerization of the styrenic diol monomer and shown to be cleanly and quantitatively converted to a non-conjugated ketone in the solid state by reaction with a photochemically-generated acid [151,348, 350]. The rearrangement reaction can be readily monitored by IR spectroscopy as the disappearance of the hydroxyl OH absorption is accompanied by appearance of a new ketone carbonyl absorption (Fig. 116). Since a polar alcohol (isopropanol) dissolves the polar diol polymer in the unexposed regions but cannot dissolve the less polar ketone polymer produced in the exposed regions, the resist functions as a negative system with alcohol as a developer. The diol polymer is stable thermally to 225 °C in the absence of acid. 

Copolymer Reactions. Rearrangement Reactions. Two poly(DHA-co-4VP) materials with 10-15 mole % DHA were thermolyzed in refluxing DMF (see Reaction 1). A strong nitrogen sparge was used to help remove the tertiary amine. The isolated poly(4-vinylpyridine-co-isopropenyl isocyanate) materials were insoluble in ether but soluble in chloroform, they had a strong band in the IR spectra at 2260 cm"1 and a weak band at 1710 cm"1, and they consisted of 1.5-2.0 wt % NCO. A sample of the thermolysis solution had a shelf life, i.e. lack of gelation, of about five days. 

PREPARATIVE TECHNIQUES The polycarbosilane employed to make commercial Nicalon SiC ceramic fiber is prepared via thermally induced rearrangement reaction of poly(dimethylsilane) or dodecamethylcyclohexasilane. 

When Curtius and Lossen rearrangement reactions are attempted on poly(acryloyl chloride), products are fairly regular polyampholytes ... 

Cyclopropanation and [2,3] Sigmatropic Rearrangement Reactions Carbene Transfer with (SBF)4PRuCO) and Poly(SBF)4PRuCO... 

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

Dimroth rearrangement, 5, 438 Imidazolium chloride, 4-chloromethyl-reaction with poly(vinyl alcohol), 1, 306 Imidazolium chloride, 2,4,5-tri(diethylamino)-reduction, 5, 415 Imidazolium complexes, 7, 746... 

There are many other examples of this type of rearrangement particularly in the reactions of poly-alkylated benzenes163 for example, the sulphonation of durene (CXXII) gives prehnitenesulphonic acid (CXXIII) and octahydrophenanthrene (CXXIV) similarly yields the octahydroanthracenesulphonic acid (CXXV), viz. 

Cycloaddition reactions of furans are still widely used as key steps in the construction of complex molecules including natural products. As an example, the intramolecular Diels-Alder cycloaddition of 2-amido substituted furans provides a useful tool for the synthesis of fused, nitrogen-containing poly-heterocycles. Thus, thermolysis of 3-substituted amidofuran produces tricyclic indolinone 39 as a 2 1 mixture of diastereomers via amidofuran cycloaddition-rearrangement methodology, which serves as a key intermediate in the total synthesis of ( )-dendrobine, a major component of the Chinese ornamental orchid Dendrobium nobile . 

Poly(vinyl alcohol) (PVA) is a polymer of great interest because of its many desirable characteristics specifically for various pharmaceutical, biomedical, and separation applications. PVA has a relatively simple chemical structure with a pendant hydroxyl group (figure la). The monomer, vinyl alcohol, does not exist in a stable form, rearranging to its tautomer, acetaldehyde. Therefore, PVA is produced by the polymerization of vinyl acetate to poly(vinyl acetate) (PVAc) followed by the hydrolysis to PVA (figure 2). Once the hydrolysis reaction is not complete, there are PVA with different degrees of hydrolysis (figure lb). For practical purposes, PVA is always a co-polymer of vinyl alcohol and vinyl acetate [1]. 

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