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Design of Bioresponsive Polymers
Published in Deepa H. Patel, Bioresponsive Polymers, 2020
Anita Patel, Jayvadan K. Patel, Deepa H. Patel
Industrially imperative products can be produced by the ROMP technique that is a kind of olefin metathesis chain-growth polymerization. The liberation of ring strain in cyclic olefins like cyclopentene or else norbornene is the instigator of the reaction and a broad variety of catalysts has been found.
Polymers as Conditioning Agents for Hair and Skin
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
GANEX series (ISP 10) are linear copolymers of PVP and long-chain α-olefins. There are four varieties, differing in the olefin copolymer: P-904 (buty lated PVP), V-216 (PVP/hexadecene), V-220 (PVP/eicosene), and WP-660 (tricontanyl PVP). They produce smooth substantive coatings on the hair. They also provide a unique "afterfeel" in skin care products (18).
Hepatotoxic and Hepatocarcinogenic Effects of Chlorinated Ethylenes*
Published in Robert G. Meeks, Steadman D. Harrison, Richard J. Bull, Hepatotoxicology, 2020
Jeffrey L. Larson, Richard J. Bull
The hepatotoxicities observed with longer exposures to the olefins tend to segregate into two distinct groups (Table 13-2). One class contains VC and probably VDC and the other class contains TCE and PCE. The changes observed with VC or VDC are comparable in some aspects to those observed with TCE or PCE. In all cases, fatty infiltration is observed, much to the same extent as in acute exposures. The noticeable difference is that continued VDC administration does lead to fatty degeneration and endoplasmic reticulum changes that are not evident with acute exposures (Prendergast et al., 1967; NTP, 1982).
Applications of fluorine to the construction of bioisosteric elements for the purposes of novel drug discovery
Published in Expert Opinion on Drug Discovery, 2021
Despite the potential attractiveness of this moiety, synthetic accessibility presented one of the main barriers to the installation of the BITE group. Typically, lengthy sequences relying on deoxyfluorination chemistry were required to achieve this though were plagued with issues arising from competing elimination processes. An alternative to this would be to develop a vicinal difluorination of olefins, and Hara and coworkers had provided an isolated report of a stoichiometric variant of this reaction in 1998 based using iodinetoluene difluoride and Et3N.5HF [194]. Inspired by this work and noting that hypervalent iodine (III) reagents in situ by treatment with Selectfluor, Gilmour et al. have developed a robust catalytic variant of this reaction using p-iodotoluene as an expensive organocatalyst and Selectfluor as the terminal oxidant. Key to the success of the reaction was the identification of a suitable HF source, and through optimization studies, an amine:HF (1:5) solution mixture comprised of Et3N.HF and Olah’s reagent to serve both as the fluoride source and Bronsted acid activator was identified as ideal to obtain high yields of the desired difluorides [195–199].
In vitro metabolism of imidacloprid and acetamiprid in rainbow trout and rat
Published in Xenobiotica, 2020
Richard C. Kolanczyk, Mark A. Tapper, Barbara R. Sheedy, Jose A. Serrano
It is the negatively charged nitro or cyano group on the neonicotinoid insecticides that interact with a unique, positively charged amino acid residue present on insect, but not mammalian nAChRs (Tomizawa & Casida, 2003). Presumably, this is also the case for fish as well as vertebrates in general which may explain the reduced acute toxicity of neonicotinoids. However, environmental breakdown and metabolism products in the form of positively charged nitrogens show a high affinity to mammalian nAChR (Tomizawa, 2004). From studies conducted with other species, metabolism of IMI is generally thought to go through two major routes; oxidation to form 5-hydroxy and the olefin or nitroreduction to form the nitroso, guanidine, and urea of IMI. The olefin formed from the hydroxylation product has been shown to be 10 times more toxic to whitefly and aphids than the parent IMI (Dai et al., 2006; Nauen et al., 2001). In contrast, the guanidine and urea products formed via nitroreduction do not impart any insecticidal properties. On the other hand, the guanidine metabolite has been reported to exhibit higher levels of mammalian toxicity than parent IMI (Tomizawa & Casida, 2003; 2005). The desnitro-imidacloprid has been shown to be higher intoxicity to mice with a reported LD50 of 16-24 mg/kg as compared to parent IMI (LD50 = 35–49 mg/kg) (Lee Chao & Casida, 1997). Relatively little neonicotinoid metabolism information for fish is available. A greater understanding of metabolism in fish is needed to determine if bioactivation to more toxic metabolites acting through the nAChR occurs.
A review of methanol poisoning: a crisis beyond ocular toxicology
Published in Cutaneous and Ocular Toxicology, 2020
Peter Pressman, Roger Clemens, Saura Sahu, A. Wallace Hayes
One of the fastest growing markets for methanol is the production of light olefins. Olefins, ethylene and propylene, are fundamental components in the plastics industry and have been typically produced from the steam cracking of ethane and naphtha. Methanol can alternatively and more cheaply be used as feedstock for olefins production.