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A cyclic ether and high-boiling solvent (b.p. 101.1 °C). Tetrahydrofuran (THF) A cyclic ether, one of the most polar simple ethers that is used as a solvent. Anisole (methoxybenzene) An aryl ether and a major constituent of the essential oil of anise seed. Crown ethers: Cyclic polyethers that are used as phase transfer catalysts. Polyethylene ...
General structure of 1,2-, 1,3-, and 1,4-dicarbonyls. In organic chemistry, a dicarbonyl is a molecule containing two carbonyl (C=O) groups.Although this term could refer to any organic compound containing two carbonyl groups, it is used more specifically to describe molecules in which both carbonyls are in close enough proximity that their reactivity is changed, such as 1,2-, 1,3-, and 1,4 ...
In chemistry, molecular symmetry describes the symmetry present in molecules and the classification of these molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can be used to predict or explain many of a molecule's chemical properties , such as whether or not it has a dipole moment , as well ...
The polar bear (Ursus maritimus) is a large bear native to the Arctic and nearby areas. It is closely related to the brown bear, and the two species can interbreed.The polar bear is the largest extant species of bear and land carnivore, with adult males weighing 300–800 kg (660–1,760 lb).
In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron.The bond angles are arccos(− 1 / 3 ) = 109.4712206...° ≈ 109.5° when all four substituents are the same, as in methane (CH 4) [1] [2] as well as its heavier analogues.
The polar reaction, N-cyclopentenyl pyrrolidine nucleophilic addition to the diazo compound, proceeds 1,500 times faster in polar DMSO than in non-polar decalin. On the other hand, a close analog of this reaction, N-cyclo hex enyl pyrrolidine 1,3-dipolar cycloaddition to dimethyl diazomalonate, is sped up only 41-fold in DMSO relative to decalin.
With the polar bear species in a fight for survival because of disappearing Arctic sea ice, a new distinct group of Greenland bears seem to have stumbled on an icy oasis that might allow a small ...
Bear habitats are generally forests, though some species can be found in grassland and savana regions, and the polar bear lives in arctic and aquatic habitats. Most bears are 1.2–2 m (4–7 ft) long, plus a 3–20 cm (1–8 in) tail, though the polar bear is 2.2–2.44 m (7–8 ft) long, and some subspecies of brown bear can be up to 2.8 m (9 ...