cis-trans isomerism

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cis-trans isomerism

[′si¦stranz ī′säm·ə‚riz·əm]
(organic chemistry)
A type of geometrical isomerism found in alkenic systems in which it is possible for each of the doubly bonded carbons to carry two different atoms or groups; two similar atoms or groups may be on the same side (cis) or on opposite sides (trans) of a plane bisecting the alkenic carbons and perpendicular to the plane of the alkenic system.
References in periodicals archive ?
(1,7,8) Reclaimed French oak in particular contained higher proportions of the trans-isomer of oak lactone rather than the cis-isomer; whereas reclaimed American oak predominantly contained cis-oak lactone.
From analytical PES in (8), we have estimated local trans-isomer at DD1 = -164.3[degrees] and DD2 = 36.7[degrees] with energy 1.72 eV below OBF-CI, and local cis-isomer at DD1 = -39.2[degrees] and DD2 = 50.9[degrees] with energy 1.28 eV below OBF-CI.
The deprotonation step, starting from the trans-[PdL.sub.2]ArX complex, is usually accepted as the dominant reaction pathway [4,23-25], but at the same time a similar reaction can take place with the corresponding cis-isomer, which is especially important for chelating ligands, where the formation of trans-[PdL.sub.2]ArX is not possible [15].
Higher temperature gave more of the thermodynamically stable trans-isomer products, while lower temperatures resulted in fast formation of the kinetically favored cis-isomer products (94% yield), (Table 4, Entry 1).
As per literature [12], cis-isomer is more preferable for hydrogen production, because dehydrogenation rate of cis-decalin is faster than that of trans-decalin [12]; cis-decalin can also be used to produce sebacic acid that is used in the manufacture of 6,10-Nylon and softeners [13].
Fermented to the same high quality as that available from Japan, the product is a "natural," all-trans CoQ10 with no cis-isomer impurities.
The acute toxicity of the cis-isomer in the rat LD50 160-300 mg/kg body weight is much higher than that of the trans-isomer LD50 > 2000 mg/kg.
As shown in Table 1, the proportion of cis-isomer decreases as the size and bulk of the alcohol solvent increases.
The activity of the cis-isomer is 7 times weaker, probably because of its nonplanar conformation.
Cis-oak lactone and trans-oak lactone: The cis-isomer is more powerfully aromatic than the trans-isomer.
The predominance of cis-isomers bioaccumulation was widely observed in all species, with R cis/trans varying between 0.60 and 29.7.