Solution, sulfuric acid contraction

For the past year Strike had been in consultation with contract labs over the making of phenylisopropyl alcohols using sulfuric acid and allylbenzenes (don t ask). The lab owners would listen patiently as Strike primitively described how and why an OH should go on the beta carbon. And without exception, the lab owners would point out to Strike that the best way to get an OH on the beta carbon would be to put a Br there first. But Strike don t wanna put a Br there first Strike would say, Strike wants the OH put on directly using sulfuric acid " The lab guys had to do what Strike said because Strike was holding all the money (...a fool and her money etc.). But out of curiosity Strike asked how they would get that Br on the beta carbon. Every one of them said it was simply a matter of using the 48% HBr in acetic acid. They even showed Strike their stock solutions (usually from Aldrich or Fisher). 

Ring contraction of a pyridazine with concurrent cyclization to indole derivatives proceeds with l-aryl-6-oxo-l,4,5,6-tetrahydro-pyridazines having at position 3 a carboxyl or methyl group (161). 137,186,707 reaction is usually performed in ethanolic solution containing hydrogen chloride or sulfuric acid, and also potassium hydroxide. Indoles of the general formula 162 (R2 = COOEt, COOH, or Me) are obtained. 

Most solutions do not exhibit ideal behavior, and the actual curve corresponding to the variation of the molar volume or enthalpy of the mixture deviates from a straight line (e.g., the solid line in Fig. 5.1). When the curve for the molar volume lies above the ideal mixture line, the system expands upon mixing when the curve lies below the line, the system contracts. In the case of the molar enthalpy, a curve that lies above the ideal mixture line corresponds to the system that absorbs heat (e.g., mixing lead bromide and water) a curve that lies below the line corresponds to the system releasing heat (e.g., mixing sulfuric acid and water). This non-ideal mixing in the case of the molar enthalpy is the principle used in cold packs and heat packs. We will develop mathematical models to describe non-ideal mixtures. We use partial molar properties in more detail later. 

With all in readiness, the methyl nitrate can be made. The most conveniently located reaction vessel is picked out, and to it is added 1/3 of the methyl alcohol-sulfuric acid mix. One third amounts to about 60 ml because of contraction of the solution during mixing. 

The mass of per unit volume of a substance is called the density of the substance. Its symbol is p, and the unit is kg/m or g/cm. When talking about daisity, temperature must be specified because the volume of the substance is changed with changing temperature due to thermal expansion and contraction. For example, the density of sulfuric acid is quite different at different temperatures. The densities of 38% sulfuric acid are 1.293,1.286, and 1.278 when the tanperatures are 10°C, 20°C, and 30°C, respectively. In this sense, when we prepare a sulfuric acid solution with a desired density, temperature should be controlled carefully. With respect to this. Table 5.2 should be very useful. 

The volume of the prepared sulfuric acid solution will be smaller than the total volume of the raw sulfuric acid and the water. This is a result of the contraction of the sulfuric acid solution. Shrinkage amounts are listed in Table 5.5 [6]. 

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