Esters cationic

In a similar manner, introduction of the ferrocenyl group drastically changes the reactivity of the mesityl enol ester cation-radicals. These cation-radicals undergo a bond scission in solution according to the following equation (Mes = mesityl) ... 

Fig. 16. Borate ester chelate complex (a) serves as precursor to catalytically active borate ester cation (b). R = alkyl, X = H, Cl, Br...

Methylene-y-lactones. Reaction of NaFp with a-bromopyruvate diethyl ketal results in the stable complex I, which on reaction with HPF is converted into the yellow crystalline, unstuhlc complex 2. The cation 2 serves an a-acrylic ester cation... 

Figure 5. L-Tyrosine derivatives (a) N-formyl-L-tyr, anionic form at moderate pH levels (b) L-tyr methyl ester, cationic form at moderate pH levels.

A kinetic investigation of the hydrolysis of 8-acetoxyquinoline in solutions of pH between 1 and 9, and in the presence and absence of copper(II) ions, yielded some interesting results (205). In the absence of copper(II), it was found that the rate of hydrolysis was first-order with respect to 8-acetoxyquinoline, but the rate equation that fitted the kinetic data was quite complex since the ester and the ester cation reacted with both the hydrogen and the hydroxide ion. In the presence of copper(II), the hydrolysis of the ester occurred more rapidly and the rate equation was found to be first-order with respect to 8-acetoxyquinoline copper(II) and hydroxide ion. Therefore, the reaction intermediate (structure XXXVII) is presumably a 1 1 chelate of copper(II) which is attacked by hydroxide ion, just as in the case of the amino acid ester. 

Poly(e-caprolactone) is another practically important polyester formed by ionic polymerization of the cyclic ester. Cationic polymerization requires relatively high temperatures this enhances proton transfer and decreases the molecular weight, whereas anionic polymerization provides living systems. 

S.D. Alexandratos, M.A. Strand, D.R. Quillen and A.J. Walder, Synthesis and characteristics of bifunctional phosphinic acid resins, Macromolecules, 1985, 18, 829 R.H. Selzer and D.G. Howery, Phosphoric acid ester cation-exchange resins. 1. Synthesis and preliminary characterization, Macromolecules, 1986, 19, 2673 Phos-phonic acid ester cation-exchange resins. 2. Physicochemical characterization, ibid. 1986, 19, 2974. 

Fig. 9. A schematic representation of the 1 1 complex between the molecular receptor l-(56) and the glycine p-nitrophenyl ester cation.

A number of new, water-stable borane cations of betaines and amino-acid esters have been characterized, i.e. Me3NBH2NMe2(CH2) C02Ef, where n=2, 3, or 4, and Me3NBH202C(CH2) NMe3, where n = 1—4. The qualitative order of stability of the betaine cations towards aqueous base is n = 1,2 > n = 3,4, while for the ester cations it is n = 2,3,4 > n = 1. °... 

A new procedure for the conversion of a y-lactone into the corresponding a-methylene-y-lactone has been developed during a total synthesis of the pseudoguaianolide ( )-aromatin (Scheme 48). The readily-prepared complex cation (97) functions as an a-acrylic ester cation equivalent, converting cyclohexanone lithium enolate into the cis- and trans-a-methylene-y-lactones (98). ... 

Nizigiyimana, L. Rajan, P.K. Haemers, A. Claeys, M. Derrick, P.J. Mechanistic Aspects of High-Energy Collision-Induced Dissociation Proximate to the Charge in Saturated Fatty Acid N-Butyl Esters Cationized with Lithium. Evidence for Hydrogen Radical Removal. Rapid Common. Mass Spectrom. 1997, 11, 1808-181Z... 

It has been demonstrated recently in the literature that cationic surfactants with orlho-esteT links can be prepared [194]. The main application areas for these novel ortho-ester cationic surfactants are seen in fields where high pH formulations are used, since the ortho-ester link shows a good hydrolytic stability at higher pH and decomposes at lower pH. 

Chem. Descrip. Ethox ated ester/cationic softener/lubricant blend Ionic Nature Nonionic/cationic Uses Water absorbent, softener for cellulosic fibers Properties Liq. 

Granular starch is contacted with solutions or suspensions of reactants, inhibitors or catalysts by soaking or spraying. After predrying, the reaction is carried out at elevated temperatures to yield - dextrins, - starch esters - cationic starches. Successful attempts have been made to react semi-dry systems yielding - extrusion cooked starches. Sometimes, excess reactants or by-products must be removed by subsequent extraction. 

Ketones from y >hydroxycarboxylic acid esters Cation speeifieity... 

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