Menschutkin reaction, and

Although Eq. (5-87) is often qualitatively obeyed, as has been frequently mentioned, there is no exact linear correlation between the rate of Menschutkin reactions and the functions of relative permittivity as in the case of Fig. 5-12 [246, 247]. A complete absence of a regular effect of changes in the dielectric properties of the solvent on the reaction rate has also been observed [248, 249]. Sometimes a satisfactory correlation has been obtained because the reaction under consideration was studied in only a limited... 

R—X, of reaction (15). It is then interesting to compare this solvent activity coefficient with those of species which may act as models for the transition state, such as ion pairs, dissociated ions, and polar 8 2 transition states (e.g. of Menschutkin reactions and of reaction (14)). In this way, some estimate of the nature of the 1 transition state can... 

Our compatriot N. A. Menshutkin made a great contribution to the development of the kinetics. In 1877 he studied in detail the reaction of formation and Iqrdrolysis of esters from various acids and alcohols and was the first to formulate the problem of the dependence of the reactivity of reactants on flieir chemical structure. Five years later when he studied the hydrolysis of tert-zmy acetate, he discovered and described the autocatalysis phenomenon (acetic acid formed in ester hydrolysis accelerates the hydrolysis). In 1887-, studying the formation of quaternary ammonium salts from amines and alkyl halides, he found a strong influence of the solvoit on the rate of this reaction (Menschutkin reaction) and stated the problem of studying the medium effect on the reaction rate in a solution. In 1888 N. A. Menschutkin introduced the term chmical kinetics in his monograph Outlines of Development of Chemical Views. ... 

The kinetic aspects of the Sn2 quaternization (the Menschutkin reaction) have been covered by Zoltewicz and Deady (78AHC(22)72), the latter author having done most of the experimental work related to pyrazoles and indazoles. In C-unsubstituted methyl deriva-... 

Fig. 5.P23. The substituent effect in the Menschutkin reaction of 1-arylethyl bromides with pyridine in acetonitrile at 35°C. Circles represent kj for the bimolecular process and squares (for the uni-molecular process.

Table 8-S. Kinetic Data on the Menschutkin Reaction of Triethylamine and Ethyl Iodide at 25°C...

Table 8-5 gives data for the Menschutkin reaction of triethylamine and ethyl... 

Figure 8-6. Ploi according to Fig. 8-5 of transfer free energies of the transition state (ordinate) and reactant state (abscissa) for the Menschutkin reaction of triethylamine and ethyl iodide. The reference solvent is N, Af-dimethylformamide (No. 27). Data are from Table 8-10, where the solvents are identified by number. Closed circles are polychlorinated solvents.

Nucleic acids are anionic under the neutral conditions. Thus, the syntheses of model compounds of the opposite charge are interesting for the discussion of electrostatic contributions in specific interactions of nucleic acids. We have tried to synthesize cationic models by the Menschutkin reaction of poly-4-vinylpyridine with 9-(2-chlo-roethyl)adenine, l-(2-chloroethyl)thymine, and 7-(2-chloroethyl)theophylline15,16 The obtained polymers are poly l-[2-(adenin-9-yl)ethyl]-4-pyridinioethylene chloride 7(APVP), poly l-[2-(thymin-l-yl)ethyl]-4-pyridinioethylene chloride 8 (TPVP), and poly l-[2-(theophyllin-7-yl)ethyl]-4-pyridiniothylene chloride 9 (THPVP), respectively. 

A 12), 0-(thymin-l-yl)ethyldodecyldimethylamrnonium chloride), 25 (T12), j3-(theophyllin-7-yl)ethyldodecylammonium chloride, 26 (TH12), j3-(adenin-9-yl)-ethyloctadecyldimethylammonium chloride (A 18), and /3-(thymin-l-yl)ethylocta-decyldimethylammonium chloride (T18)47. These model compounds were prepared by the Menschutkin reaction of dodecyldimethyl amine or octadecyldimethylamine with chloroethylated bases. 

The Menschutkin reaction was carried out as a test reaction to show the feasibility of such novel micro flow concepts that allow to process fouling-sensitive reactions (see also Section 4.2.6 here another test reaction is decribed for the same purpose) [78]. The reaction of alkyl bromide with ternary bases such as pyridine or triethylamine gives quaternary salts insoluble in most solvents. Often, fairly rapid precipitation of this salt occurs, hence ideally serving as a test reaction for fouling sensitivity of micro-channel devices. The reaction of 4,4 -bipyridyl and ethyl bromoacetate [78] belongs to the category of fast-predpitating Menschutkin reactions, as the halide function is activated by the carbonyl fimction. 

To pursue the development of environmentally benign synthesis routes for ionic liquids, the alkylation step (Menschutkin reaction) was investigated by the authors in detail. The preparation of the ionic liquid 1-hexyl-3-methyhmidazohum chloride ([CeMlMJCl) was taken as a representative experiment (Scheme 7.2). The process parameters temperature (T = 70-100°C), solvent (ethanol, xylene, cyclohexane, n-heptane, solvent free), concentration of the N-base (c = 1.6-6.7 M), molar ratio n n = 1 0.5-1 4) and reaction time (f = 10-144 h) were investigated. In addition, the N-base was altered in order to proof the transferability of the reaction parameters. 

In this contribution, we describe and illustrate the latest generalizations and developments[1]-[3] of a theory of recent formulation[4]-[6] for the study of chemical reactions in solution. This theory combines the powerful interpretive framework of Valence Bond (VB) theory [7] — so well known to chemists — with a dielectric continuum description of the solvent. The latter includes the quantization of the solvent electronic polarization[5, 6] and also accounts for nonequilibrium solvation effects. Compared to earlier, related efforts[4]-[6], [8]-[10], the theory [l]-[3] includes the boundary conditions on the solute cavity in a fashion related to that of Tomasi[ll] for equilibrium problems, and can be applied to reaction systems which require more than two VB states for their description, namely bimolecular Sjy2 reactions ],[8](b),[12],[13] X + RY XR + Y, acid ionizations[8](a),[14] HA +B —> A + HB+, and Menschutkin reactions[7](b), among other reactions. Compared to the various reaction field theories in use[ll],[15]-[21] (some of which are discussed in the present volume), the theory is distinguished by its quantization of the solvent electronic polarization (which in general leads to deviations from a Self-consistent limiting behavior), the inclusion of nonequilibrium solvation — so important for chemical reactions, and the VB perspective. Further historical perspective and discussion of connections to other work may be found in Ref.[l],... 

As early as 1967, after their success in isolating atropisomers of haloacetamide derivatives (12), Chupp and Olin (49) examined the separate reactivities of these atropisomers in Menschutkin reactions with pyridine (Scheme 7). They found... 

Figure 11.6 Menschutkin reaction of ammonia and chloromelhane. In the gas phase nucleophilic displacement fails to take place, while in water solvation of the anions allows the reaction to proceed...

Heterocyclic amines have also been used as phase transfer catalysts. However, because these amines quaternize easily, the question is whether the operative catalyst is the tertiary amine or the quaternary ammonium salt formed in situ Furukawa et al.286 have shown that a methyl 2-pyridyl sulfoxide may be used as a phase transfer catalyst and promote substitution reactions between lithium chloride or sodium cyanide and benzyl bromide. According to the authors, the catalyst behaves as a cation complexer and not as a quaternary ammonium salt formed in situ by a Menschutkin reaction. 

The Menschutkin reaction has been used to prepare poly(viologens) (115) directly (Scheme 31). These polymers were found to be quite useful as polyelectrolyte redox-polymers and for the preparation of conductive polymers when complexed with the 7,7, 8,8 -tetracyanoquinodimethane (TCNQ) radical anion (71MI11100). 

Information as to the nature of the transition state in reaction (71) may be obtained through a comparison of AG f(Tr) values with those for other transition states and those for various model solutes. Data are available62 on solvent effects on the transition state in the Menschutkin reaction... 

The hydrolysis of ethanoic anhydride [47] and the reaction between phenacyl bromide and pyridine to give phenacylpyridinium bromide (Equation 3.29, an example of the Menschutkin reaction) are reported cases of kinetics studies by conductance monitoring [48],... 

This type of reaction is usually promoted by applied pressure and some of the examples have been reviewed by us [87]. The Menschutkin reaction of the phenazine 137 with the allyl bromide 138 occurs only in poor yield with elimination of HBr from 138, whereas at 1.2 GPa and rt the reaction constitutes a total synthesis of phenazinomycin (139), a rare type of phenazine antibiotic, albeit only in 20% yield (Scheme 38) [88]. 

Secondly, we note that if we take the charge development from the values of Z in Table 18 then again the transition states are much too reactant-like. Hence we prefer to use the values of JZ. This means that the transition states for the Menschutkin reactions of methyl and ethyl iodide are fairly loose 0.65). This inference may seem to conflict with the good agreement... 

Solvent effect on rate constants. In this section, the rate constant will be predicted qualitatively in CO2 for the Diels-Alder cycloaddition of isoprene and maleic anhydride, a reaction which has been well-characterized in the liquid state (23,24). In a previous paper, we used E data for phenol blue in ethylene to predict the rate constant of the Menschutkin reaction of tripropylamine and methyliodide (19). The reaction mechanisms are quite different, yet the solvent effect on the rate constant of both reactions can be correlated with E of phenol blue in liquid solvents. The dipole moment increases in the Menschutkin reaction going from the reactant state to the transition state and in phenol blue during electronic excitation, so that the two phenomena are correlated. In the above Diels-Alder reaction, the reaction coordinate is isopolar with a negative activation volume (8,23),... 

Two-fold Menschutkin reactions on 4,4 -bipyridine provide a route to compounds containing a redox-active paraquat unit [15]. Thus, reacting 54 with 6-to-syloxyhexyl thioacetate afforded 55 (Scheme 10.17). Perylene tetracarboxylic dii-mide presents another electron acceptor that has been functionalized with thiol end-groups. Thus, heating a mixture of the dianhydride 56 and 4-aminothiophe-nol (57) gave the product 58 (Scheme 10.18) [16],... 

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