The General Reaction

Let s examine the reaction of chloromethane with hydroxide ion in detail. We say that hydroxide ion has substituted for chlorine on the methyl group, so this type of reaction is termed a substitution reaction. 

Look for this logo in the chapter and go to OrganicChemistryNow at http //now.brookscole.com/hornback2 for tutorials, simulations, problems, and molecular models. 

The concept of nucleophiles and electrophiles is one of the most important in organic chemistry. The reactions in this chapter, as well as most of the reactions that we will study in later chapters, involve a nucleophile bonding to an electrophile. If you can examine a molecule and identify whether it has a nucleophilic or an electrophilic site, not only will you know where that molecule is likely to react but you will also be able to identify what kind of partner is needed for a reaction because nucleophiles react with electrophiles. 

Because the nucleophile replaces the leaving group, this type of reaction is termed a nucleophilic substitution reaction. A more general equation for a nucleophilic substitution reaction is 

---

For gas reactions where the gases are assumed to follow ideal behaviour this equation becomes AG° = RT]n Kp, where Kp is defined in terms of the partial pressures of reactants and products. Thus for the general reaction above,... 

The student should carry out the following simple experiments with acetamide or with any other ahphatic amide, e.g., n-caproamide they illustrate some of the general reactions of primary ahphatic amides. 

The precipitated amine hydrochloride (or sulphate), if any, dissolves during the diazotisation to give a clear solution of the highly soluble diazonium salt. The general reaction may be written ... 

Section IV, 135,5), but are unaflFected by the dimedone reagent (Section 111,70, 2). The general reactions are similar to those already given under Aliphatic Ketones (Section 111,74). Owing to their higher molecular weight, such derivatives as oximes and phenylhydrazones are frequently quite satisfactory. 

A study of the kinetics of a chemical reaction begins with the measurement of its reaction rate. Consider, for example, the general reaction shown in the following equation, involving the aqueous solutes A, B, C, and D, with stoichiometries of a, b, c, and d. 

Of course, in reactions (5.A) and (5.B) the hydrocarbon sequences R and R can be the same or different, contain any number of carbon atoms, be linear or cyclic, and so on. Likewise, the general reactions (5.C) and (5.E) certainly involve hydrocarbon sequences between the reactive groups A and B. The notation involved in these latter reactions is particularly convenient, however, and we shall use it extensively in this chapter. It will become clear as we proceed that the stoichiometric proportions of reactive groups-A and B in the above notation—play an important role in determining the characteristics of the polymeric product. Accordingly, we shall confine our discussions for the present to reactions of the type given by (5.E), since equimolar proportions of A and B are assured by the structure of this monomer. 

Many specific reaction conditions using otiiei alkylene oxides (14) oi combinations of alkylene oxides (15) may be found in tiie patent Hteiatuie. DiaZotlZatlon. The general reactions of o-diamines with an alkali nitrite and an acid with subsequent ting closure are well known. 

The reductions of chlorosilanes by lithium aluminum hydride, lithium hydride, and other metal hydrides, MH, offers the advantages of higher yield and purity as well as dexibiUty in producing a range of siUcon hydrides comparable to the range of siUcon haUdes (59). The general reaction is as follows ... 

Batteries are miniatuie chemical leactois that convert chemical energy into electrical energy on demand. The thermodynamics of battery systems foUow direcdy from that for bulk chemical reactions (10). For the general reaction... 

The most important rechargeable lithium batteries are those using a soHd positive electrode within which the lithium ion is capable of intercalating. These intercalation, or insertion, electrodes function by allowing the interstitial introduction of the LE ion into a host lattice (16,17). The general reaction can be represented by the equation ... 

Some of the general reactions for the boron trihalides where X represents Cl, Br, or 1 and X a different halogen, ate... 

The polyimide shown is a tme thermosetting resin, but the general reaction procedure, coupling the dianhydride with the diamine, is extremely important throughout polyimide chemistry. The intermediate polyamic acid polymers form the basis for many of the polyimide resins used in advanced composites. 

AH commercial copper extractants selectively extract copper from weakly acidic aqueous leach solutions by the general reaction... 

In electrode kinetics a relationship is sought between the current density and the composition of the electrolyte, surface overpotential, and the electrode material. This microscopic description of the double layer indicates how stmcture and chemistry affect the rate of charge-transfer reactions. Generally in electrode kinetics the double layer is regarded as part of the interface, and a macroscopic relationship is sought. For the general reaction... 

The reactions of carboxyUc acids and anhydrides with epoxy resins have been extensively studied in a variety of investigations, particularly References 27—31. The general reaction of epoxide resins and anhydrides is... 

For combustion of simple hydrocarbons, the oxidation reactions appear to foUow classical first-order reaction kinetics sufficiently closely that practical designs can be estabUshed by appHcation of the empirical theory (8). For example, the general reaction for a hydrocarbon ... 

The deposition of metals directly from these halides would require high temperatures to be efficient, but because of the thermodynamic stabilities of the hydrogen halides, direct reduction can readily be carried out with hydrogen at lower temperamres. The general reaction... 

A free-radical reaction is a chemical process which involves molecules having unpaired electrons. The radical species could be a starting compound or a product, but the most common cases are reactions that involve radicals as intermediates. Most of the reactions discussed to this point have been heterolytic processes involving polar intermediates and/or transition states in which all electrons remained paired throughout the course of the reaction. In radical reactions, homolytic bond cleavages occur. The generalized reactions shown below illustrate the formation of alkyl, vinyl, and aryl free radicals by hypothetical homolytic processes. 

A number of polyethylene glycols are also available in molecular weight ranges from commercial suppliers. These are made by initiating the polymerization of ethylene oxide by hydroxide ion. The corresponding monomethyl (or monoalkyl ethers) can be made in a similar fashion by initiating the polymerization with an alcohol. The general reaction is shown below in Eq. (7.2). 

The general reaction procedure and apparatus used are exactly as described in Procedure 2. Ammonia (465 ml) is distilled into a 2-liter reaction flask and to this is added 165mlofisopropylalcoholandasolutionof30g(0.195 mole) of 17/ -estradiol 3-methyl ether (mp 118.5-120°) in 180 ml of tetrahydrofuran. The steroid is only partially soluble in the mixture. A 5 g portion of sodium (26 g, 1.13 g-atoms total) is added to the stirred mixture and the solid dissolves in the light blue solution within several min. As additional metal is added, the mixture becomes dark blue and a solid (matted needles) separates. Stirring is inefficient for a few minutes until the mass of crystals breaks down. All of the sodium is consumed after 1 hr and 120 ml of methanol is then added to the mixture with care. The product is isolated as in Procedure 4h 2. After being air-dried, the solid weighs 32.5 g (ca. 100% for a monohydrate). A sample of the material is dried for analysis and analyzed as described in Procedure 2 enol ether, 91% unreduced aromatics, 0.3%. The crude product may be crystallized from acetone-water or preferably from hexane. 

A great many reactions in solution can profitably be treated by an extension of the earlier ideas to include more than one progress variable. We will introduce the idea with the general reaction... 

When Brj nsted plots apply to the rates and equilibria of the same reaction, a further restriction can be written for the coefficients. Let the generalized reaction scheme be... 

A recent adaptation of the procedure employing perchlorate and fluoro-borate salts has been reported by Leonard and Paukstelis (J5). This report includes proof of structure by direct comparison to iminium salts prepared by protonation of enamines. The general reaction reported was that of a ketone or aldehyde with a secondary amine perchlorate to give iminium salts. A large structural variety of carbonyl compounds and several amine... 

Intermolecular insertion of SO2 can also occur (without prior formation of an isolable complex) and the general reaction can be represented by the equation " ... 

Finally, the borohydrides An(BFl4)4 must be mentioned.Those of Th and U were originally prepared as part of the Manhattan Project and those of Pa, Np and Pu have been prepared more recently, all by the general reaction... 

On the basis of the general reaction scheme (see p. 248) the kinetic dependence is caused by the fact that the rate of the 8 2 reaction, Eq. (7), is dependent on the concentration of diazomethane but that the rate of the SkI reaction, Eq. (6), is not. (For unimolecular reactions, the half-life does not depend on the concentration but it does in the case of bimolecular reactions. We have, assuming fast pre-equilibrium ... 

Attempts to prepare selenazole derivatives were first described by Hofmann,2 a student of Hantzsch, in connection with investigations in the thiazole series. By reaction of selenobenzamide with a-halogeno compounds corresponding to the general reaction (2, R" = CeHg), he synthesized a series of 2-phenylselenazoles. In the same way, several... 

Phenylhydrazine Methods.—In addition to the general reaction between almost all aldehydes and ketones and hydroxylamine, there is another... 

Every chemical reaction can go in either forward or reverse direction. Reactants can go forward to products, and products can revert to reactants. As you may remember from your general chemistry course, the position of the resulting chemical equilibrium is expressed by an equation in which /Cec], the equilibrium constant, is equal to the product concentrations multiplied together, divided by the reactant concentrations multiplied together, with each concentration raised to the power of its coefficient in the balanced equation. Eor the generalized reaction... 

Notes. (1) Iron wire of 99.9 per cent purity is available commercially and is a suitable analytical standard. If the wire exhibits any sign of rust, it should be drawn between two pieces of fine emery cloth, and then wiped with a clean, dry cloth before use. The general reaction which occurs has been given in Section 10.92. 

The electroinsertion reaction of mobile lithium ions into a solid carbon host proceeds according to the general reaction scheme... 

The most serious acute Type I reaction is the generalized reaction, the anaphylactic shock. Anaphylactic shock results from a generalized release of mediators from mast cells and basophils. The clinical symptoms are manifested predominantly in... 

---