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15-Crown-5 is a crown ether with the formula (C 2 H 4 O) 5. It is a cyclic pentamer of ethylene oxide that forms complex with various cations , including sodium (Na + ) [ 2 ] and potassium (K + ); [ 3 ] however, it is complementary to Na + and thus has a higher selectivity for Na + ions.
Alexander William Williamson in his late years. Williamson was born in 1824 in Wandsworth, London, the second of three children of Alexander Williamson (originally from Elgin) a clerk with the East India Company and his wife, Antonia McAndrew, daughter of a prominent London merchant. Despite early physical infirmity, the loss of sight in one ...
Luminiferous aether or ether [1] (luminiferous meaning 'light-bearing') was the postulated medium for the propagation of light. [2] It was invoked to explain the ability of the apparently wave -based light to propagate through empty space (a vacuum ), something that waves should not be able to do.
4th-century BC – Aristotle publishes Physics, in which the aether is briefly described as being an element lighter than air that surrounds celestial bodies.He describes the aether in relation to other elements – aether is lighter than air and is located above it, whereas air is lighter than water, and water is lighter than earth.
The Williams diagram is universal in the sense that it is applicable to both premixed and non-premixed combustion. In supersonic combustion and detonations , the diagram becomes three-dimensional due to the addition of the Mach number M a = u ′ / c {\displaystyle Ma=u'/c} as the z-axis, where c {\displaystyle c} is the sound speed .
As a consequence, alkoxides (and hydroxide) are powerful bases and nucleophiles (e.g., for the Williamson ether synthesis) in this solvent. In particular, RO − or HO − in DMSO can be used to generate significant equilibrium concentrations of acetylide ions through the deprotonation of alkynes (see Favorskii reaction). [36] [37]
Crown ether coordinating a potassium ion. Charles John Pedersen (Japanese: 安井 良男, Yasui Yoshio, October 3, 1904 – October 26, 1989) was an American organic chemist best known for discovering crown ethers and describing methods of synthesizing them during his entire 42-year career as a chemist for DuPont at DuPont Experimental Station in Wilmington, Delaware, and at DuPont's Jackson ...
Elemicin has been synthesized from syringol and allyl bromide using Williamson ether synthesis and Claisen rearrangement. [5] [6] The electrophilic aromatic substitution entering the para-position was made possible by secondary Cope rearrangement. [7] This is due to syringol's allyl aromatic ether being blocked by ethers in both ortho-positions.