Hexenyl-9-BBN

Preparation of Boriozirconocene Complex 16 (Scheme 7.5) [33] To a stirred ice-cooled suspension of the Schwartz reagent (0.26 g, 1 mmol) in dry CH2C12 (1 mL) was added a solution of B-hexenyl-9-BBN 15 (0.20 g, 1 mmol) in dry CH2C12 (1 mL). The resulting cloudy mixture became a dear yellow solution in 1 h at 0 °C (or 10 min at ambient temperature), indicating the formation of 16. 

The combination of versatile chemistry and similarity to aluminum makes boron an attractive choice for protecting group chemistry. This has been amply demonstrated in a series of papers by Chung et al. from work initially carried out at Exxon. Patents published in 1988 disclose the use of boron-functionalized monomers in both homo- and copolymerizations using heterogeneous TiCla (pretreated with aluminum alkyl) AlEt2Cl formulations. - Monomers were prepared by monohydroboration of dienes (1,4-pentadiene, 1,7-octadiene, etc.) with 9-borabicyclo-[3.3.1]nonane (9-BBN). Near quantitative yields of the homopolymers of 7-octenyl-9-BBN and 5-hexenyl-9-BBN could be obtained (eq 6). 

BBN), these copolymers could also be cleanly converted to the alcohol derivatives under similarly mild conditions. The reported copolymer was shown to have a composition that was the same as that of the monomer feed (one to one). A later report showed that 5-hexenyl-9-BBN is slightly less reactive than... 

Propylene was also copolymerized with 5-hexenyl-9-BBN using a TiCL/AlEts catalyst. In this case, the monomers have substantially different reactivity (n = 70.5 for propylene (Mi) and rz = 0.028 for... 

Polymers have intruded into our daily life, and it looks impossible to remain isolated without these molecules. Consequently, a lot of work is being carried out in various research laboratories to synthesize new types of polymers with better physical and chemical properties. The development of different organob-oranes is also contributing significantly for their preparation. Chung et al [ 1 ] have prepared functionalized copolymer by Ziegler-Natta process, employing 9-(5-hexenyl)-9-BBN and 1-octene to yield octane-hexenol copolymer. 

For experimental convenience, aii borane groups in copolymers were oxidized to hydroxyi groups. The numbers of POH-13, POH-11 and POH-31 indicates the moiar feed ratios of two monomers, 1-octene and hexenyl-9-BBN, respectively. The steady increase in the Tg is characteristic of the increase in the hexenol content with increasing borane monomer in the feed. The presence of only one glass transition is taken as evidence for the absence of macroscopic phase separation and therefore impiies that the copoiymer samples are fairly homogeneous. The same conclusion was reached on the basis of GPC results which were obtained by using both UV and Rl detectors. The hydroxyl groups in copoiymers were esterified by benzolic chloride to obtain THF soluble and UV-... 

Table 1 Copolymerization reactions between ethylene (Mi) and 5-hexenyl-9-BBN (M2) using various catalysts, including [( -C5Me4)SiMe2-( 7 -NCMe3)]TiCl2/MAO (I), Et(Ind)2ZrCl2/MAO (II), Cp2ZrCl2/MAO (III), and TiCls AA/Et2AlCl (IV)...

Fig. 1 GPC curves of poly (ethylene-co-5-hexenyl-9-BBN) copolymers containing (a) 0.5 and (b) 1.2 mol% of 5-hexenyl-9-BBN...

Table 2 Sununary of copolymerization reactions between propylene or 1-octene and 5-hexenyl-9-BBN using TiCls AA/Et2AlCl catalyst...

---