Excess molar

The molar excess enthalpy h is related to the derivatives of the activity coefficients with respect to temperature according to... 

A more active product is obtained by the following slight modification of the above procedure. Dissolve the succinimide in a slight molar excess of sodium hydroxide solution and add the bromine dissolved in an equal volume of carbon tetrachloride rapidly and with vigorous stirring. A finely crystalline white product is obtained. Filter with suction and dry thoroughly the crude product can be used directly. It may be recrystallised from acetic acid. 

Similarly, molar excess functions have been determined for various thiazole-solvent binary mixtures (Table 1-46) (307-310). 

PARTIAL MOLAR EXCESS ENTHALPY AT INFINITE DILUTION OF THIAZOLE IN VARIOUS SOLVENTS AT SIS.IS K... 

These condensations are carried out by slow addition at room temperature of the halomethylketone to the dithiocarbamate, the latter in 10 to 50% molar excess to prevent the formation of 2-ketonylthiothiazoles (270, 291). 

When the pyrolysis gases are quenched with a molar excess of iodine vapor, a yield of greater than 50% -xylylene diiodide is recovered. The observation of this effect offered the first direct chemical support for the idea that DPX pyrolysis results in PX (1) (3). 

Hoffman Degradation. Polyacrylamide reacts with alkaline sodium hypochlorite [7681-52-9], NaOCl, or calcium hypochlorite [7778-54-3], Ca(OCl)2, to form a polymer with primary amine groups (58). Optimum conditions for the reaction include a slight molar excess of sodium hypochlorite, a large excess of sodium hydroxide, and low temperature (59). Cross-linking sometimes occurs if the polymer concentration is high. High temperatures can result in chain scission. 

A.ctivity Coefficients. Activity coefficients in Hquid mixtures are directiy related to the molar excess Gibbs energy of mixing, AG, which is defined as the difference in the molar Gibbs energy of mixing between the real and ideal mixtures. It is typically an assumed function. Various functional forms of AG give rise to many of the different activity coefficient models found in the Hterature (1—3,18). Typically, the Hquid-phase activity coefficient is a function of temperature and composition expHcit pressure dependence is rarely included. 

The propyne (b.p. —23.2°) is precondensed to the mark in a volumetric flask cooled by acetone-dry ice. Evaporation of some propyne during addition will lead to a moderate molar excess of l-bromo-3-chloropropane, regarded as desirable in preventing formation of diyne product. 

In the manufacture of resols a molar excess of formaldehyde (1.5-2.0 1) is reacted with the phenol in alkaline conditions. In these conditions the formation of the phenol alcohols is quite rapid and the condensation to a resol may take less than an hour. A typical charge for a laboratory-scale preparation would be ... 

The molar excess of di-isocyanate is about 30% so that the number of polyesters joined together is only about 2-3 and the resulting unit has isocyanate end groups. A typical structure, with P for polyester groups, U for urethane and I for isocyanates would be... 

The usefulness of the Grignard reagent of 3-bromothiophene is somewhat limited as it can only be prepared by the entrainment method. The simultaneous formation of Grignard reagents from 3-bromothiophene and a fivefold molar excess of ethyl bromide gave, however, a 55% yield of 3-thiophenecarboxylic acid upon carbona-tion. With acetaldehyde, a 55% yield of methyl 3-thienyl carbinol... 

When [EMIMJCl is present in a molar excess over AICI3, only equilibrium (2.1-1) need be considered, and the ionic liquid is basic. When a molar excess of AICI3 over [EMIMJCl is present on the other hand, an acidic ionic liquid is formed, and equilibria (2.1-2) and (2.1-3) predominate, further details of the anion species present may be found elsewhere [23]. The chloroaluminates are not the only ionic liquids prepared in this manner. Other Eewis acids employed have included AlEtCl2 [24], BCI3 [25], CuCl [26], and SnCl2 [27]. In general, the preparative methods employed for all of these salts are similar to those indicated for AlCl3-based ionic liquids as outlined below. 

Some degree of regioselectivity can be imposed on l//-azepine formation if the arene has substituents of high steric demand.63 For example, the thermolysis of ethyl azidoformate in a tenfold molar excess of 1,4-di-fert-butylbenzene yields a 95 5 mixture of the di-zerr-butyl-l//-azcpincs 3 and 4, crystallization of which yields the pure 3,6-di-/er/-butyl isomer 3. 

The iron complex 16 in anhyd benzene was treated with an alkyl halide (excess) and anhyd NaHC03 (1 mol equiv) and the mixture was stirred at 20 "C for 20 h. For acylation, an acyl chloride (1 mol equiv) and anhyd NaHCO, were employed and the mixture was stirred at 20CC for 1-2 h. For decomplexation, the TV-substituted iron complex 17 and a 20-fold molar excess of freshly sublimed Me3NO in acetone were stirred for 20 h at 20 C and the reaction mixture was worked up by chromatography to give 18. 

A solution of the sulfoxide in THF is added to a slight molar excess of LDA in Till- while maintaining the temperature below —75 C. then the a-haloester is added dropwisc to the yellowish solution of the anion at the same temperature. The usual workup gives optically active product in high yield. 

This product is supplied by Fluka AG, Buchs, Switzerland. The amount of dispersion used should provide 6.25 g. (0.26 mole) of pure sodium hydride. A small molar excess is used to allow for variation in the sodium hydride oil ratio of commercial material. 

A 10% molar excess of the oxonium salt with regard to the carboxylic acid gives slightly higher yields than does an equimolar quantity. 

Ethyl acrylate is used in approximately 50% molar excess over the expensive, limiting reagent, iodine. Use of an equimolar amount results in a lower yield (85%). The checkers distilled the reagent at 20° (39 mm.) prior to use. 

All chemicals used were reagent grade unless otherwise specified. A 50 % molar excess of reagents was employed throughout the synthesis in order to drive the reactions to completion. 

The activity coefficient y,fpr) is determined by differentiation of gE, the molar excess Gibbs energy at reference pressure Pr,... 

It was mentioned earlier (Sec. 8.6) that for iodo-de-diazoniation no catalyst is necessary because the redox potential of the iodide ion (E° = 1.3 V) is sufficient for an electron transfer to the arenediazonium ion. The reaction was actually observed by Griess (1864 c). Four iodo-de-diazoniation procedures are described in Organic Syntheses. For the syntheses of iodobenzene and 4-iodophenol (Lucas and Kennedy, 1943, and Daines and Eberly, 1943, respectively) KI is used in equimolar quantity and in 1.2 molar excess. However, for 2-bromoiodobenzene and for 1,3,4-triiodo-5-nitrobenzene (replacement of a diazonio group in the 4-position by iodine), up to... 

Addition of up to a tenfold molar excess of hydrogen chloride did not appreciably alter the reaction rate. Orton and Bradfield227 obtained the same kinetic form for the chlorination of formanilide, acetanilide, benzanilide, and benzene-sulphonanilide in 99 % aqueous acetic acid at 20 °C reaction rates were higher than previously obtained with the less aqueous medium, and this medium effect has been subsequently found to be general. 

Bradfield et al.21g first studied the kinetics of molecular bromination using aromatic ethers in 50% aqueous acetic acid at 18 °C. They showed that the kinetics are complicated by the hydrogen bromide produced in the reaction which reacts with free bromine to give the tribromide in BrJ, a very unreactive electrophile. To avoid this complication, reactions were carried out in the presence of 5-10 molar excess of hydrogen bromide, and under these conditions second-order rate coefficients (believed to be I02k2 by comparison with later data) were obtained as follows after making allowance for the equilibrium Br2 + Br7 Bn, for which K = 50 at 18 °C 4-chloroanisole (1.12), 4-bromoanisole (1.20), 4-... 

---