No applications are commercialized for polyphosphazenes. The cyclic trimer hexachlorophosphazene ((NPCl 2 ) 3 ) is commercially available. It is the starting point for most commercial developments. High performance elastomers known as PN-F or Eypel-F have been manufactured for seals, O-rings , and dental devices. An aryloxy-substituted polymer has also been developed as a fire resistant expanded foam for thermal and sound insulation . The patent literature contains many references to cyclomatrix polymers derived from cyclic trimeric phosphazenes incorporated into cross-linked resins for fire resistant circuit boards and related applications.
(b) ALS inhibitors: The acetolactate synthase (ALS) enzyme (also known as acetohydroxyacid synthase, or AHAS) is the first step in the synthesis of the branched-chain amino acids (valine, leucine, and isoleucine). These herbicides slowly starve affected plants of these amino acids which eventually lead to inhibition of DNA synthesis. They affect grasses and dicots alike. The ALS inhibitor family includes sulfonylureas (SUs), imidazolinones (IMIs), triazolopyrimidines (TPs), pyrimidinyl oxybenzoates (POBs), and sulfonylamino carbonyl triazolinones (SCTs). ALS is a biological pathway that exists only in plants and not in animals thus making the ALS-inhibitors among the safest herbicides.
Phenoxy herbicides (or "phenoxies") are a family of chemicals related to the growth hormone indoleacetic acid (IAA). When sprayed on broad-leaf plants they induce rapid, uncontrolled growth ("growing to death"). When sprayed on monocotyledonous ( grass ) crops such as wheat or corn , they selectively kill broad-leaf weeds , leaving the crops relatively unaffected. The wide variety of phenoxies in use today can be grouped into the phenoxyacetic , phenoxybutyric and phenoxypropionic subtypes, the latter containing the aryloxyphenoxypropionic subtype with the greatest number of commercial variants. Chemically, they are carboxylic acids , typically applied in an ester or salt form.