Quaternary ammonium analogs

Civoli F, Daniel LW (1998) Quaternary ammonium analogs of ether lipids inhibit the activation of protein kinase C and the growth of human leukemia cell lines. Cancer Chemother Pharmacol 42 319-326... 

The most successful of these products contain high ratios of VP to DMAEMA and are partially quatemized with diethyl sulfate (Polyquaternium 11) (142—144). They afford very hard, clear, lustrous, nonflaking films on the hair that are easily removed by shampooing. More recendy, copolymers with methyl vinyl imidazoliiim chloride (Polyquaternium 16) (145) or MAPTAC (methacrylamidopropyltrimethyl ammonium chloride) (Polyquaternium 28) have been introduced. Replacement of the ester group in DMAEMA with an amide analog as in Polyquaternium 28 results in a resin resistant to alkaline hydrolysis and hence greater utility in alkaline permanent-wave and bleach formulations (see Quaternary ammonium compounds). 

The Hofmann elimination reaction is not often used today in the laboratory, but analogous biological eliminations occur frequently, although usually with protonated ammonium ions rather than quaternary ammonium salts. In the biosynthesis of nucleic acids, for instance, a substance called adenylosuccinate... 

The azide form of the quaternary ammonium ion exchange resin IR-400 (which exhibits low lfiction-sensitivity) reacts with bromoform, analogously to dichloro-and dibromo-methane, to form the highly explosive triazidomethane. Solutions of above 50% concentration explode in contact with a pipette or on injection into a GLC inlet port. 

The rate of reaction of phosphorus oxychloride with phenols to produce triaryl phosphates is increased by the addition of quaternary ammonium salts and the reaction temperature can be reduced without loss of overall yield [1,2]. The analogous reaction between phenoxide anions and thiophosphoryl chloride produces aryl phosphoro-dichloridothoates [3]. As with the acylation of enolizable (3-dicarbonyl compounds (3.3.12), phosphorylation leads to the predominant formation of the E-O-phos-phoryiated derivatives [4,5]. 

In contrast with the reactions involving sulphide or hydrogen sulphide anions, aryl alkyl thioethers and unsymmetrical dialkyl thioethers (Table 4.3) are obtained conveniently by the analogous nucleophilic substitution reactions between haloalkanes and aryl or alkylthiols under mildly basic conditions in the presence of a quaternary ammonium salt [9-15] or polymer-supported quaternary ammonium salt [16]. Dimethyl carbonate is a very effective agent in the formation of methyl thioethers (4.1.4.B) [17]. 

In a manner analogous to that used for the formation of 5-alkyl thioacetates using a polymer-supported quaternary ammonium salt (4.1.31), the dithiocarbamate anion can be 5-alkylated under mild conditions [3]. The corresponding arylation reaction with activated aryl systems requires more vigorous conditions ... 

The mechanism [26] of the oxidation of non-terminal aikynes by quaternary ammonium permanganates to give vicinal diketones [e. g. 18, 27] has been studied. Normally, terminal aikynes are totally oxidized in acetic acid to carboxylic acids [13, 27, 28] using a procedure analogous to 10.2.4. 

The use of cerium(IV) salts as catalytic oxidation mediator is restricted by their insolubility in non-aqueous media. Cerium(IV) ammonium nitrate (CAN) may be used in organic solvents upon the addition of quaternary ammonium salts, but cerium(IV) sulphate is not transferred under analogous conditions. Bis(tetra-/t-butyl-ammonium) hexanitratocerate(IV) is obtained in a solid form by metathesis of CAN... 

Nitroarenes are reduced to anilines (>85%) under the influence of metal carbonyl complexes. In a two-phase system, the complex hydridoiron complex [HFe,(CO)u]2-is produced from tri-iron dodecacarbonyl at the interface between the organic phase and the basic aqueous phase [7], The generation of the active hydridoiron complex is catalysed by a range of quaternary ammonium salts and an analogous hydrido-manganese complex is obtained from dimanganese decacarbonyl under similar conditions [8], Virtually no reduction occurs in the absence of the quaternary ammonium salt, and the reduction is also suppressed by the presence of carbon monoxide [9], In contrast, dicobalt octacarbonyl reacts with quaternary ammonium fluorides to form complexes which do not reduce nitroarenes. 

Although the effect of quaternary ammonium salts on the stereochemistry of the two-phase condensation reaction of a-chloroacetonitrile with acrylonitriles to form cyclopropanes [4, 7] is not as pronounced as with the Darzens reaction, it can be rationalized in an analogous manner (Scheme 12.2). In the absence of the catalyst, the more highly stabilized anion (4a) is favoured leading to the preferential production of the cis isomer (5). As with the Darzens reaction, addition of the catalyst causes diffusion of the anions (4a) and (4b), as ion-pairs, into the bulk of the organic phase where their relative stabilities are similar and a more equal ratio of the two isomeric cyclopropanes (5) and (6) results (Table 12.2). 

A slow non-competing liquid/liquid reaction with no catalyst present gave only 78 % O-alkylation. Thus the active site of the lipophilic phosphonium ion catalysts appears to be aprotic, just as in analogous phase transfer catalyzed alkylations with soluble quaternary ammonium salts 60), Regen 78) argued that the onium ion sites of both the 17% and the 52% RS tri-n-butylphosphonium ion catalysts 1 are hydrated, on the basis of measurements of water contents of the resins in chloride form. Mon-tanari has reported measurements that showed only 3.0-3.8 mols of water per chloride ion in similar 25 % RS catalysts 74). He argued that such small hydration levels do not constitute an aqueous environment for the displacement reactions. No measurements of the water content of catalysts containing phenoxide or 2-naphthoxide ions have been reported. 

Monolayers are best formed from water-insoluble molecules. This is expressed well by the title of Gaines s classic book Insoluble Monolayers at Liquid-Gas Interfaces [104]. Carboxylic acids (7-13 in Table 1, for example), sulfates, quaternary ammonium salts, alcohols, amides, and nitriles with carbon chains of 12 or longer meet this requirement well. Similarly, well-behaved monolayers have been formed from naturally occurring phospholipids (14-17 in Table 1, for example), as well as from their synthetic analogs (18,19 in Table 1, for example). More recently, polymerizable surfactants (1-4, 20, 21 in Table 1, for example) [55, 68, 72, 121], preformed polymers [68, 70, 72,122-127], liquid crystalline polymers [128], buckyballs [129, 130], gramicidin [131], and even silica beads [132] have been demonstrated to undergo monolayer formation on aqueous solutions. 

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