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General structure of an imine. Schiff bases are imines in which R 3 is an alkyl or aryl group (not a hydrogen). R 1 and R 2 may be hydrogens General structure of an azomethine compound. In organic chemistry, a Schiff base (named after Hugo Schiff) is a compound with the general structure R 1 R 2 C=NR 3 (R 3 = alkyl or aryl, but not hydrogen).
A primary imine in which C is attached to both a hydrocarbyl and a H (derived from an aldehyde) is called a primary aldimine; a secondary imine with such groups is called a secondary aldimine. [10] A primary imine in which C is attached to two hydrocarbyls (derived from a ketone) is called a primary ketimine; a secondary imine with such groups ...
In cosmology, the study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies.
Sodium triacetoxyborohydride (STAB, NaBH(OAc) 3) is a common reducing agent for reductive aminations. STAB selectively reduces the imine intermediate formed through dehydration of the molecule. [8] STAB is a weaker reductant than NaBH 4, and can preferentially reduce the imine group in the presence of other reduction-sensitive functional groups ...
In astronomy, galactocentrism is the theory that the Milky Way Galaxy, home of Earth ' s Solar System, is at or near the center of the Universe. [1] [2]Thomas Wright and Immanuel Kant first speculated that fuzzy patches of light called nebulae were actually distant "island universes" consisting of many stellar systems. [3]
The Staudinger synthesis, also called the Staudinger ketene-imine cycloaddition, is a chemical synthesis in which an imine 1 reacts with a ketene 2 through a non-photochemical 2+2 cycloaddition to produce a β-lactam 3. [1] The reaction carries particular importance in the synthesis of β-lactam antibiotics. [2]
A few minutes into the expansion, when the temperature was about a billion kelvin and the density of matter in the universe was comparable to the current density of Earth's atmosphere, neutrons combined with protons to form the universe's deuterium and helium nuclei in a process called Big Bang nucleosynthesis (BBN). [35]
The center of the Universe is a concept that lacks a coherent definition in modern astronomy; according to standard cosmological theories on the shape of the universe, it has no distinct spatial center. Historically, different people have suggested various locations as the center of the Universe.