ethynyl


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ethynyl

[′eth·ə‚nil]
(organic chemistry)
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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Substitution of fluorine with various chromophores can be done by using aryl nucleophiles or ethynyl nucleophiles (Scheme 1) to create a large, virtual Stokes shift, anywhere in the range of 8,000 [cm.sup.-1] to 16,000 [cm.sup.-1] (Ulrich et al.
The activities of compounds 25 ([IC.sub.50] = 0.2 nM, with a hydroxyl group), 4 ([IC.sub.50] = 20 nM, with an ethynyl group), and 8 ([IC.sub.50] = 300 nM, with a methyl group), differing in the substituent on C6, varied according to this electrostatic feature.
Furthermore, the original pill contained 150 mcg of ethynyl oestrogen which causes serious complications of dotting and embolism so the amount of oestrogen was reduced to 50 mcg, then 35 then 20 mcg, yet the pill was still said to have a 2% failure rate and a 40% ovulation breakthrough.
Comparative estrogenicity of estradiol, ethynyl estradiol and diethylstilbestrol in an in vivo, male sheepshead minnow (Cyprinodon Oariegatus), vitellogenin bioassay.
Chapters address lab-scale and larger-scale synthesis of azide compounds; azides by olefin hydroazidation reactions; the chemistry of vinyl, allenyl, and ethynyl azides; small rings by azide chemistry; Schmidt rearrangement reactions with alkyl azides; radical chemistry with azides; cycloaddition reactions with azides; dipolar cycloaddition reactions in peptide chemistry; the azide/nitrene interface and the photochemistry of azides; organoazides and transition metals; azide-containing high energy materials; azide chemistry in rotaxane and catenane synthesis, aza-Wittig reaction in natural product synthesis; and azides in carbohydrate chemistry.
The team's experiments indicate that triacetylene can be formed by a single collision of a "radical" ethynyl molecule and a diacetylene molecule.
The reactive molecule ethynyl ([C.sub.2]H) persists, so its emissions can reveal the temperature, density, and other properties of massive star-forming regions, the researchers report in the March 1 Astrophysical Journal Letters.
"If there is clinical significance, we need to think about whether the appropriate dose of ethynyl estradiol for teens may be 35 mcg and whether the trade-off with the risk of VTE--which is relatively small in adolescents--is acceptable." Other questions include whether and to what degree bone mass recovery occurs after cessation of these agents and whether lifestyle factors, including nutrition and physical activity, can override some of the negative bone effects.
"If there is clinical significance, we need to think about whether the appropriate dose of ethynyl estradiol for teens may be 35 mcg and whether the trade-off with the risk of VTE--which is relatively small in adolescents--is acceptable." It also needs to be clarified whether bone mass recovery occurs after cessation of these agents and whether lifestyle factors can override some of the negative bone effects, she said.
What about the impact of the presence of an ethynyl substituent in the 17 position of an estradiol molecule, or the role of micronized progesterone?
The C18 phase resolves beta-estradiol and ethynyl estradiol, which have differing functional groups, but cannot resolve ethynyl estradiol and norethindrone, which differ in fused ring structure.
Jowle, 59, of Halesowen, West Midlands, escaped a ban in November last year after magistrates heard that the Listerine label mentioned "ethynyl", but did not say this was alcohol.