Diynes, hydroboration polymerization

N. Matsumi, M. Miyata, and Y. Chujo, Synthesis of organoboron Tr-conjugated polymers by hydroboration polymerization between heteroaromatic diynes and mesitylborane and their light emitting properties, Macromolecules, 32 4467-4469, 1999. 

Table 1. Hydroboration Polymerization of Aromatic Diynes Using Mesilylborane. ...

Acetylenes are known to be reactive toward hydroboration reaction as well as dienes. Accordingly, hydroboration polymerization with monoalkylborane can also be applied to diynes. Generally, the reactivity of a terminal acetylene group toward hydroboration is quite different from that of an internal acetylene group. That is, the terminal... 

HYDROBORATION POLYMERIZATION OF DICYANO COMPOUNDS The organoboron polymers prepared by hydroboration polymerization of dienes or diynes are relatively unstable toward air as mentioned before. On the other hand, the preparation of stable boron-containing polymers has been an attractive target as polymeric materials, for which... 

Recently, we explored a novel polyaddition between dienes and monoalkylboranes and termed this hydroboration polymerization (18). Diynes and dicyano compounds can also be used in this hydroboration polymerization. The organoboron polymers obtained are effectively converted to polyalcohols or polyketones. In other words, polymers having organoboron units in the main chains can be expected to be reactive polymers. Here, the scope of these hydroboration polymerizations is viewed as methodologies for the preparation of organoboron polymers. 

Hydroboration Polymerization of Diynes with Thexyl-borane... 

As a typical example for hydroboration polymerization of internal diyne, the reaction of 3,9-dodecadiyne and thexylborane was carried out in THF at 0°C under nitrogen (20). The polymerization behavior was quite similar to hydroboration polymerization of dienes. The organoboron polymer obtained was a colorless wax and soluble in common organic solvents such as benzene, THF or chloroform. An IR spectrum of the polymer showed the absorption band assignable to C=C bond, which was also supported by H- and B-NMR spectra. 3,8-Undecadiyne and 3,10-tridecadiyne were also used in hydroboration polymerization with thexylborane to produce the corresponding organoboron polymers. 

A wide range of novel polymers with boron in the backbone have been prepared by means of boration polymerizations (65,70-82). Diynes can be polymerized by hydroboration (70,71), phenylboration (65), and haloboration (72) to yield polymers (14),(15), and (16) (eq. 17). When an appropriate aromatic or heteroaromatic diyne is used, the resulting polymers have been shown to have extended 7T-conjugation through the vacant p-orbital of the boron atom (73,74). In fact, several have been shown to exhibit blue fluorescence emission. 

Hydroboration of terminal diyne gives organoboron polymer having branched structure due to the further hydroboration reaction toward the initially formed vinylborane structures. That is, terminal diynes are taken to have a potential as a multifunctional monomer. When the polymerization between 1,7-octadiene and thexylborane was carried out in the presence of a small amount of 1,7-octadiyne, the molecular weights of organoboron polymers were found to be increased when the ratio of diyne/diene was increased [5]. 

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