NO, general reactions

D) No general reaction can be cited for the preparation of crystalline derivatives of Class (iii). Triphenylamine, when nitrated in acetic acid with fuming nitric acid, gives tri-/>-nitrophenylamine, m.p. 280°. The presence of substituents in the phenyl groups may however complicate or invalidate nitration. 

The addition of an organometallic to an unactivated olefin is generally difficult to control since such an addition may lead to polymerization of the olefin unless the final organometallic adduct is stabilized, or has a structural modification. Thus, no general reaction for the intermolecular carbometallation of alkenes is known, although since the last review concerning this topic [3], many relevant papers have appeared. 

For a high-temperature combustion process in practical engineering, no generalized reaction rate can theoretically be formulated since combustion involves complicated chain reactions. In fact, the combustion rate is often expressed in an empirical formula in terms of the concentrations of the fuel and oxidant ... 

Persistent efforts and satisfoctory experiments. There are no general reactions (Woodward, 1969). For this or other reasons, not all attempts to effect a known reaction succeed with a particular substrate, even in the hands of veteran experimentalists. Success in the synthesis of organic compounds demands a certain persistence, even though much labor can be finfit-lessly expended to induce desirable chemical changes to take place and run to completion. Intense heating, for example, meant to force such a reaction to occur, can unexpectedly change colorless crystals to an opaque and intractable tar. Such a result, unsuccessful as it is, nonetheless represents a satisfactory experiment, if other, less brutal but more numerous bids merely demonstrate the inadequacy of the reaction conditions used. 

Oxa-Michael addition reactions are well known and the protected j0-hydroxy carbonyl compounds so produced are of significant importance in organic synthesis [127]. To our knowledge, however, no general reaction has been reported in which j8-alkoxy ketones can be prepared via Michael addition. We first detect-... 

This equation has been shown to be correct for di- and trivalent ions, but tetra-valent ions in general show a more complex behavior. The extracted complex is sometimes further solvated in the organic phase and nitrate, chloride, and even perchlorate complexes may be involved in the extraction reaction, depending on the specific aqueous conditions employed. Thus, no general reaction can be proposed which will account... 

Heck Coupling. The Heck reaction is the common name for the coupling of an organopalladium species with an alkene and includes both inter- and intramolecular reaction types. However, no general reaction conditions exist and the multitude of variations can sometimes seem confusing. 

CFIDF end group, no selective reaction would occur on time scales above 10 s. Figure B2.5.18. In contrast to IVR processes, which can be very fast, the miennolecular energy transfer processes, which may reduce intennolecular selectivity, are generally much slower, since they proceed via bimolecular energy exchange, which is limited by the collision frequency (see chapter A3.13). 

Aliphatic and aromatic acids, simple and substituted, vary con siderably in their properties, and no one reaction for the preparation of crystalline derivatives is general. The following are recommended as most promising. 

Di- and poly-halogenated aliphatic hydrocarbons. No general procedure can be given for the preparation of derivatives of these compounds. Reliance must be placed upon their physical properties (b.p., density and refractive index) and upon any chemical reactions which they undergo. 

The nitrosation of tertiary alkylammes is rather complicated and no generally use ful chemistry is associated with reactions of this type... 

The isomerization of oxaziridines (1) to acid amides with migration of a substituent from C to N is a general reaction and is always observed when no other reactions predominate under the relatively harsh conditions (heating to above 150 °C or photolysis). Even then one can make acid amide formation the main reaction by working at 300 °C (57JA5739) and by dilution techniques. For example, caprolactam (63) is formed in 88% yield by flash pyrolysis of oxaziridine (52) at about 300 °C, whereas decomposition of (52) at lower temperatures gives almost no (63) (77JPR274). 

No unambiguous reactions of unfused azetes have been reported rather, the existence of transient azetes has been inferred from the observation of products which might reasonably be attributed to their further reaction. Separate discussion of reactivity and preparation is, therefore, inappropriate, and apart from a few general comments is deferred to Section 5.09.5.3. 

With a reactive solvent, the mass-transfer coefficient may be enhanced by a factor E so that, for instance. Kg is replaced by EKg. Like specific rates of ordinary chemical reactions, such enhancements must be found experimentally. There are no generalized correlations. Some calculations have been made for idealized situations, such as complete reaction in the liquid film. Tables 23-6 and 23-7 show a few spot data. On that basis, a tower for absorption of SO9 with NaOH is smaller than that with pure water by a factor of roughly 0.317/7.0 = 0.045. Table 23-8 lists the main factors that are needed for mathematical representation of KgO in a typical case of the absorption of CO9 by aqueous mouethauolamiue. Figure 23-27 shows some of the complex behaviors of equilibria and mass-transfer coefficients for the absorption of CO9 in solutions of potassium carbonate. Other than Henry s law, p = HC, which holds for some fairly dilute solutions, there is no general form of equilibrium relation. A typically complex equation is that for CO9 in contact with sodium carbonate solutions (Harte, Baker, and Purcell, Ind. Eng. Chem., 25, 528 [1933]), which is... 

There is no general explicit mathematical treatment of complicated rate equations. In Section 3.1 we describe kinetic schemes that lead to closed-form integrated rate equations of practical utility. Section 3.2 treats many further approaches, both experimental and mathematical, to these complicated systems. The chapter concludes with comments on the development of a kinetic scheme for a complex reaction. 

All the halide exchange reactions mentioned above proceed more or less quantitatively, causing greater or lesser quantities of halide impurities in the final product. The choice of the best procedure to obtain complete exchange depends mainly on the nature of the ionic liquid that is being produced. Unfortunately, there is no general method to obtain a halide-free ionic liquid that can be used for all types of ionic liquid. This is explained in a little more detail for two defined examples the synthesis of [BMIM][(CF3S02)2N] and the synthesis of [EMIM][BF4]. 

The first unequivocal evidence for the AE + DE mechanism came in three papers by Zollinger (1955 a-c) dealing with general base catalysis and primary kinetic hydrogen isotope effects in azo coupling reactions of various types. Three classes of reactions were identified i) reactions with no isotope effects (ArH/A D - 1.0) and no general base catalysis, ii) others with large isotope effects (k /k — 6.5) and (practically) linear base catalysis, and iii) intermediate cases with isotope effects of around 3.0 and less-than-linear base catalysis. 

In all cases, besides resulting in good to excellent yields, the microwave-assisted multistep syntheses resulted in much faster reactions compared to earlier published procedures at atmospheric pressure under conventional heating conditions. It is also noteworthy that in some cases the strong thermal effect due to graphite/microwave interaction, can efficiently be used for the synthesis of heterocyclic skeletons, especially benzothiazoles but, in fact, there is no general rule and some reactions performed in the presence of solvent may sometimes be more convenient than the same dry-media conditions. 

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