Organosilicon quaternary ammonium salts

Another possibility for surface-bonded antimicrobial activity is the use of organosilicon quaternary ammonium salts (Si-QAQ. Isquith et al. (1972) have demonstrated that the hydrolysis product of 3-(trimethox-ysilyl)-propyldimethyloctadecyl ammonium chloride (18.1.10.) exhibits antimicrobial activity against a broad range of micro-organisms while chemically bonded on a variety of surfaces. 

An antibacterial nylon filament yam was also prepared by composite spinning with antibacterial zeolite into which silver ions have been replaced. Toyobo[103] prepared a non-elution type antibacterial and odor preventing nylon fiber in which a quaternary ammonium salt is bonded to the fiber via organosilicon. 

Currently, it is fair to say that asymmetric synthesis using chiral quaternary ammonium fluorides remains an underdeveloped field, and the various useful stereoselective carbon-carbon bond-forming processes described in this chapter are only the start of an exploration of the vast synthetic potential of this process, particularly when combined with current knowledge of organosilicon chemistry. It seems that the key issue to be addressed is the rational molecular design of chiral quaternary ammonium cations with appropriate steric and electronic properties. These are expected to be readily tunable to impart not only a sufficient reactivity but also an ideal chiral environment to the requisite nucleophile involved in a desired chemical transformation. Clearly, the continuous accumulation of information related to the structure of fluoride salts and their reactivity and selectivity should create a solid basis for this field, offering - in time - a unique yet reliable tool for sophisticated bond construction events with rigorous stereocontrol, under mild conditions. 

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