Spiro polymerization reaction

FIGURE 6.30 a,cu-Bis(tocopheryl)alkanes (36) and other a, >-bis(hydroxyphenyl)-alkanes (37-40) as starting materials for the spiro oligomerization/spiro polymerization reaction. 

The spiro polymerization is a novel reaction type that uses the spiro dimerization of o-QMs to build up linear oligomers and polymers. The basic properties of the spiro dimer of a-tocopherol, that is, its fluxional structure and its ready reduction to the ethano-dimer, remain also active when such structural units are bound in the polymer. The products of the reaction, both in its poly(spiro dimeric) form (41) and in the form of the reduced polytocopherols (42), are interesting materials for application as high-capacity antioxidants, polyradical precursors, or organic metals, to name but a few. 

Nesvadba [2] used both aromatic and cyclohexene spiro-ketal derivatives, (I) and (II), respectively, as free radical polymerization reaction regulators. 

Pentaerythritol was chosen since it forms spiro compounds very readily and gives high enough yields to be used in a polymerization reaction with dialdehydes (, 1 )). Thus it was reasoned that a similar reaction with a cyclic diketone should produce a polyspiroketal. Thus, when 1,4-cyclohexanedione was heated in benzene with pentaerythritol plus a trace of -toluenesulfonic acid (PTSA) and the resulting water (93%) was removed by distillation, a white polymer precipitated. The spiro polymer I was shown by X-ray analysis to be highly crystalline and decomposed at 350°C without melting. It was almost completely insoluble in most solvents but was completely soluble in hot hexafluoroisopropanol. 

Vinylpyridines add to TV-alkyl- or phenyl-substituted maleimides to give unexpected 1 2 and 1 3 adducts. From the reaction of 2-vinylpyridine 99 with N-alkylmaleimides the 1 2 addition products 154, which are tetra-hydroquinoline derivatives, could be isolated in the presence of polymerization inhibitors. Furthermore, 1 3 adducts 155 are formed, representing an unusual type of cycloaddition involving the pyridine ring. On the other hand, 4-vinylpyridine 156 combines with 3 moles of dienophilic N-alkylmaleimides in the presence of polymerization inhibitors to afford the spiro compounds 157 (73HCA440). 

The anodic oxidation of spiro[4,9 -fluorenyl]-2,6-diphenyl-4//-thiopyran at high potential leads to deposition on the anode of polymeric material which consists of a polyphenylene framework bearing thiopyran or thiopyrylium substituents depending on the oxidation state. This conducting material is electrochromic, appearing blue, red, or yellow according to its oxidation state. It is proposed that the reaction proceeds via a radical thiopyran cation. 

This reaction is thermodynamically controlled, because the polymer containing 1,3-dioxolane rings converts itself to a polyether when allowed to stand at room temperature for several days or heated at 80 °C for a few hours in the presence of an acid catalyst. Similar double ring-opening polymerizations were observed for 2,6,7-trioxabicyclo[2.2.2]octane and its derivatives [86, 87] and for spiro orthoesters and spiro orthocarbonates as well (see Sects. 6 and 7). 

The reaction of N3P3C16 with 1,3-diaminopropane and 1,4-diaminobutane (1 2 and 1 3) in suitable non-polar solvents allows the synthesis in a very high yield of the PNHR-containing DISPIRO and TRISPIRO derivatives without any significant side-polymerization, Another example of a DISPIRO structure was recently reported 66) upon the reaction of N3P3C16 with 1,3-dihydroxypropane together with its SPIRO-ANSA isomer. 

Methylenecyclopropanes, although usually stable at ambient temperature, do undergo efficient oligomerization and polymerization when heated to form a variety of linear and cyclic products. From transition metal catalyzed reactions of this kind, the spiro-fused di- and trimerization products are most remarkable and useful from a synthetic point of view. 

Polymerization of Spiro[2.n]alkanes. Spiro[2.6]nonane (M5), spiro [2.7]decane (M(i), and spiro[2.1 ljtetradecane (M7) were prepared from the corresponding methylenecycloalkanes (methylenecycloheptane, meth-ylenecyclooctane, and methylenecyclododecane, respectively) by the Simmons and Smith reaction (14) see Equation 8. 

Another compound, DDFB, was also investigated to determine its potential as a dual radical/cationic polymerization initiator with the SOCM monomer. The dark DDFB solid had only limited solubility in the monomer (approximately 0.5 wt%). The activated SOCM sample was heated to 100 C for 10 min which produced a darkened polymer that was predominantly crosslinked. An unactivated SOCM control sample also received the same heat treatment and was recovered unchanged. The IR spectrum of the polymer showed extensive carbonate formation in the 1800 and 1750 cm regions and a nearly complete disappearance of the spiro absorption bands. This initiator appeared to have little affinity for the methacrylate double bond since a strong 1637 cm band was still present. The attempted polymerization of oxaspiro monomer 10 with DDFB at 100 C yielded no polymer and no reaction. The DDFB-containing SOCM monomer sample was then irradiated under the sunlamp with no polymer formation observed after 30 min. 

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