AlltransIsomer

AlltransIsomer refers to a class of chemical species in which every carbon–carbon double bond in the molecule adopts a trans (E) configuration. It is not a single compound but a descriptor for molecules with multiple double bonds or similar stereochemical constraints where all such bonds are arranged to lie on opposite sides of the bond. The term is commonly applied to polyenes, carotenoids, and unsaturated fatty acids.

Structural and property implications of the all-trans arrangement are notable. The all-trans geometry tends to produce a more linear, extended skeleton, enhancing conjugation along the chain and enabling tighter packing in the solid state. This often leads to higher melting points and distinctive optical properties, such as a bathochromic (red) shift in UV–visible absorption compared with cis forms. In carotenoids and related natural products, the all-trans form is typically the thermodynamically favored and most abundant form, while exposure to light or heat can generate cis isomers.

Examples and contexts. Natural carotenoids such as all-trans beta-carotene and all-trans lycopene are widespread in plants and provide color and photosynthetic roles. In nutrition and food chemistry, all-trans configurations may also describe trans fatty acids, which arise from industrial hydrogenation or partial hydrogenation and differ in physical properties and health considerations from naturally occurring cis fats. In analytical contexts, all-trans configurations give characteristic spectroscopic and chromatographic behavior used to distinguish isomeric forms.

In sum, alltransIsomer denotes the all-trans arrangement across multiple double bonds, yielding distinct structural, physical, and spectral properties relative to cis isomers.