Onium compounds

As can be expected, given the high bond energy (in analogy to the C—C bond), these substances are extremely hard and have extremely small volatility (p. 96). 

In graphite, which can be considered as a giant two-dimensional molecule from the series of condensed rings, the bonding between the separate layers is very weak, being due, as in molecular lattices, to Van der Waals-London interaction. The now infinite system of n electrons results in metallic conduction, only, however, in the plane of the rings Boron nitride has perhaps also a diamond-like form as well as the common graphite-like modification (p. 235). 

In this it makes no difference that, as in the ammonium ion and for example in an amine oxide, 

Lowry and Sidgwick used for this bond between nitrogen and oxygen the names semi-polar double bond (covalent bond + ionic bond) or coordinate link and the symbol — The direction of the arrow indicates the direction of the electron transfer, thus 

We reject these terms and symbols as misleading and superfluous 

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Anionic extractants are commonly based on high molecular weight amines. Metal anions such as MnO or ReO can be exchanged selectively with inorganic anions such as Cl or The equiHbrium for a quaternary onium compound of organic radicals R for two anion species A and B ... 

Quaternary Salts. Herbicides paraquat (20) and diquat (59) are the quaternary salts of 4,4 -bipyridine (19) and 2,2 -bipyridine with methyl chloride and 1,2-dibromoethane, respectively. Higher alkylpyridinium salts are used in the textile industry as dye ancillaries and spin bath additives. The higher alkylpyridinium salt, hexadecylpytidinium chloride [123-03-5] (67) (cetylpyridinium chloride) is a topical antiseptic. Amprolium (62), a quaternary salt of a-picohne (2), is a coccidiostat. Bisaryl salts of butylpyridinium bromide (or its lower 1-alkyl homologues) with aluminum chloride have been used as battery electrolytes (84), in aluminum electroplating baths (85), as Friedel-Crafts catalysts (86), and for the formylation of toluene by carbon monoxide (87) (see QuaternaryAA ONiUM compounds). 

Also the reaction of triphenylarsenic dihalides with acetonitrile leads to the onium compounds.243,244 An example... 

It is interesting to compare the nucleophilicity sequence found by Liotta and Grisdale (1975) for crown ethers, with the sequence recently reported by Landini et al. (1978) for onium compounds. For hexadecyltributylphos-phonium as the cation, the reactivity sequence (for n-octyl methanesulfonate) in chlorobenzene was CN- > > Cl- > Br- > I- > SCN- (Table 28), which... 

NS-bis-alkyl-onium and S,S-bis-alkyl-onium compounds also have neuromuscular blocking activity [3—6]... 

Muir, T.C. and Lewis, J.J. (1959) Neuromuscular blocking activity in some NS-bis-onium compounds. /. Pharm. Pharmacol., 11 (Suppl), 91T—94T. 

Water-soluble quaternary AA (onium compound) QAS phase separation Formulated with amine salt containing alkyl or hydroxylalkyl groups (1-3 carbons) or ammonium salt, and optionally a solvent Baker Petrolite (Przbylinski and Rivers, 2003) Shell (Blytas and Kruka, 2001)... 

G. B. Kauffman and I. Bernal, Overlooked opportunites in stereochemistry, part 2 the neglected connection between Werner s metal-ammines and Pope s organic onium compounds , J. Chem. Educ., 1989, 66, 293-300. 

Sheets EB, Rhodes D (1996) Determination of DMSP and other onium compounds in Tetraselmis subcordiformis by plasma desorption mass spectrometry. In Kiene RP, Visscher PT, Keller MD, Kirst GO (eds) Biological and environmental chemistry of DMSP and related sulfonium compounds. Plenum Press, New York, pp 55-63 Sieburth JM (1960) Acrylic acid, an antibiotic principle in Phaeocystis blooms in Antarctic waters. Science 132 676-677... 

The singly positively charged nitrogen N+ is isoelectronic with carbon and thus this will form bonds of the same kind. Methane is isoelectronic with the tetrahedrally built ammonium ion. These bonds are of quite the same nature as those between formally neutral atoms (see 25, onium compounds). 

Atoms with an incomplete octet can likewise form bonds with atoms with lone electron pairs. Thus similarly to the onium compounds, the amine oxides, the sulphoxides and sul-phones are produced by addition of an oxygen atom to the nitrogen or sulphur atom of amines or sulphides. 

Also, the PET between excited states of donors and various onium compounds yields radicals [11, 52, 117-123]. However, the mechanism in the presence of monomers is very complicated due to the interaction possible between excited species and monomers see Scheme 9. So far, many details of that scheme are unsolved or not strongly supported by experimental data. 

Of the substances that interfere with gibberellin biosynthesis, mention should first be made of the so-called onium compounds, which are substances with a charged central atom (5, 6). They include the already extensively employed bioregulators chlormequat chloride (CCC) and mepiquat chloride (DPC) (Figure 1). 

The retardation effect of all these substances can be reversed by gibberellins. Furthermore, it has been possible, in the case of some of these substances, to detect precisely the point of attack or site of action in the gibberellin biosynthesis sequence. As can be seen from Figure 3, it is assumed that the onium compounds inhibit the cyclization of geranylgeranyl pyrophosphate to copalyl pyrophosphate (7), whereas it has been demonstrated in cell-free systems that pyrimidines, norbornenodiazetines, and triazoles inhibit the sequential oxidation of ent-kaurene to ent-kaurenoic acid (fj, 9). 

Gibberellins Phthalimides Steroids Steviol Onium compounds (N, S, P) Pyrimidines Norbornenodiazetines Triazoles... 

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