Ethyl group composition

Elemental composition Pb 64.06%, C 29.70%, H 6.23%. Tetraethyl lead is dissolved in benzene or toluene, diluted appropriately, and analyzed by GC/MS. The ethyl group may be determined by NMR spectroscopy. 

Attempts to isolate the complex which forms trans polymer have been made, but no pure compounds have yet been isolated. From cobalt chloride, solid or liquid products were obtained which have variable composition. (Co = 5.7-15%, A1 = 5.2-10.6%, Cl = 20.6-26.2%, N = 4.5%, and replaceable ethyl groups 1.2-16.9%). It seems probable that in certain of these products some of the amine cobalt chloride complex is present without coordinated AlEt2Cl. The corresponding products from cobalt octoate have all undergone decomposition to a greater or lesser extent during isolation, but by suitably protecting the catalyst with other donors such as ethers or nonpolymerizable dienes, it may be possible to isolate a stable product. 

The composition of the reactor effluent depends on the molar ratio of the-benzene to the ethyl groups in the feed. It has been demonstrated that the optimal conditions are satisfied with values of this parameter between 2 and 2.5. In this case, the alkylate obtained has the following composition ethylbenzene 41 to 43 weight per cent, benzene 38 to 40, diethylbenzenes 12 to 14, triethyl nzenes 2 to 3, heavier polyethylbenzenes 1.5 to 2, miscellaneous 1.5 to 2. Any decrease in the ratio of benzene to ethyl groups has the effect of reducing the formation of the higher molecular weight components. 

A further example of the influence of steric interference in ether adducts of BF3 was provided by a comparison of the stabilities of (C2H5)20-BF3 and (CH2)40-BF3. Although the atomic compositions of these molecules differed only by two protons, the enthalpy of association of the latter molecule exceeded that of the former by more than 40%. It seems clear that the increase in stability of the tetrahydrofuran complex must be attributed to the ring structure of the donor which locks the interfering ethyl groups out of the way of the fluorine atoms, thus eliminating, or at least reducing, steric interference (3, 17). 

The occurrence of both alkylation and transalkylation reactions results in a reaction chemistry that is affected by equilibrium. The equilibrium has been studied and is illustrated in Fig. 1. The horizontal axis is the ratio of ethyl groups to benzene rings and is often referred to as the ethyl-to-phenyl ratio. In the case of an alkylation reaction, the ethyl-to-phenyl ratio is the moles of ethylene to moles of benzene. Similarly, for a transalkylation reaction, the ethyl-to-phenyl ratio is equivalent to the moles of ethyl groups contributed by PEB to the moles of phenyl groups contributed by PEB plus benzene. At ethyl-to-phenyl ratios above about 0.6, the equilibrium EB concentration is relatively constant at about 48wt% whereas the PEB concentration continues to increase as the ratio approaches 1.0. Most commercial reactors operate with ethyl-to-phenyl ratios less than 0.6. The equilibrium composition varies only slightly across the temperature range of commercial interest. 

Cairns and Neustadter (1975) studied the stability of carbon dispersions stabilized by BP 45, a copolymer of methacrylic esters for which R in the ester group -COOR could be the straight chain C4 or Cg-iz alkyl groups, or the amino substituted ethyl group -CH2CH2NH2. They also studied the stabilizer PV30-TEPA, a succinimide terminated poly(isobutylene). Flocculation was induced by the addition of ethanol to the dispersion medium, which was n-heptane. Their results, which compare the CFVs with the 0-compositions determined by the method of Comet and van Ballegooijen (1966), are presented in Table 9.1. 

It is not surprising that the composition of sterols varies depending on the source from which they have been derived. Table 2 shows the composition of sterols from soy oil, tall oil, and lanolin alcohol. Despite the very different sources the molecular structure is fairly similar in all types of sterols. Figure 1 depicts the structure of the most commonly found sterols it should be noted that the most abundant sterols in animal sources (cholesterol) and vegetable sources (sitosterol) differ only by an ethyl group in the hydrocarbon tail of the sterol. 

An unusual way to produce butene-1 copolymers with other linear olefins has been described 165,166) , these copolymers were obtained starting from p-olefins as a result of a monomer isomerization process. The isomerization of butene-2 and pentene-2 to butene-1 and pentene-1 was confirmed by the presence of the 766 cm (ethyl group) and 740 cm" (propyl group) bands, and the copolymer compositions were measured as functions of the 766Mi3so ratios 166). 

The copolymer compositions have been measured mainly by IR methods, for example (42) by using the 746 cm" band (ethyl group mode) and 1180 cm" band [isopropyl group mode, insensitive to monomer distribution (53)]. 

When racemic 3,7-dimethyloctene-l and 3-methylpentene-l were polymerized respectively with (s)-3-methylpentene-l and (r)-3,7-di-methyloctene-1 177), the optical activity and the IR analysis of the copolymer fractions demonstrated that copolymerization takes place predominantly between the optically active monomer and the monomer in the racemic mixture having the same chirality, the other antipode giving the homopolymer. Copolymer formation in these cases was detected by the IR method, using the ratio of the absorbances of the 763 cm" band (ethyl group mode in 3-methylpentene-l units) and those of the 732 cm tard [(CHjla rocking mode of the 3,7-dimethyloctene-l units] as a qualitative measure of the copolymer composition. 

Although a number of cellulose ethers are known, the ethyl derivative is the only member finding plastics uses, mainly as a surface coating others are water-soluble and are used in food processing. Commercial ethyl cellulose contains 2.15 to 2.6 ethyl groups per repeat unit and is obtained by treatment of alkali cellulose with ethyl chloride. It finds use in compositions for the strippable protection of metal parts. 

These two substances of the same composition are formed in different ways. In the one, the ethyl group is fixed by an atomicity of the first order and in the other by an atomicity of the second order. Since these two atomicities of different kinds cannot be identical, the two compounds cannot be identical either, they should be two isomeric substances. 

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