double bond


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dou·ble bond

a covalent bond resulting from the sharing of two pairs of electrons, for example, H2C=CH2 (ethylene).

dou·ble bond

(dŭb'ĕl bond)
A covalent bond resulting from the sharing of two pairs of electrons.
References in periodicals archive ?
The reduction products of the various olefins would require the elimination of fluorine or chlorine from the molecule and substitution by hydrogen atom across the double bond. Table 3 gives summary of potential reduction products if they would occur with various olefin refrigerants.
The positions of the hydroxyl moieties and the double bonds in the molecule were assigned by coupling constants, 1H-1H COSY and HMBC correlations.
Equation (1)--Determination of residual double bonds at time=0 ([A.sub.0]) and t ([A.sub.t])
On the other hand, a signal around [delta] 1.20 ppm, assigned to aliphatic C[H.sub.2] ([H.sub.4]-4[H.sub.-7] and [H.sub.14]-[H.sub.-17]) of AcFAD (which is not present in the reference emulsion) was observed and the acrylic double bond signals (at [delta] 5.76, 6.04, and 6.33 ppm, [H.sub.-23a], [H.sub.-22], and [H.sub.-23b], respectively) disappeared, indicating complete polymerization of AcFAD.
To investigate the reactivity of the double bond in the AF material and the possibility of interaction with the peroxide molecules C-NMR analysis was performed.
So, the first product correspond to the isomerization of the terminal double bond, the other products are the two stereoisomers of the terminal double bond hydrogenation.
C2-C3 double bond and 3'4'-OH group might not be important for antiplatelet aggregation: Rutin isoquercitrin and hesperetin showed similar inhibiting affinities on ADP-induced platelet aggregation with inhibitory rates of 55.342.09% 52.274.65% and 50.80 7.03% respectively.
(6) Despite the high DC achieved in dental resins, complete conversion of aliphatic carbon-carbon double bonds is typically not achieved.
It is evident that, following the oxidization reaction, the peak at 3010 [cm.sup.-1] corresponding to the double bond stretching vibration is lost, while a small peak at 840 [cm.sup.-1] due to the epoxide group appears [13].
The addition of the double bond into the mix makes the compounds generally more reactive than their fluoroalkane (that is, saturated) equivalents.
The difference between Z907 (Figure 1(b)) and SG1051 (Figure 1(c)) was just the double bonds on the edge of alkyl chain on the dye.
Among many steroids tested, those possessing a carbonyl group at position 3, a methyl group at 7, a hydroxyl group at positions 1, 2, 4, 11, or 19, or a saturated B ring, with or without a 4-5 double bond, were inactive.