Hexyleneglycol

For hydrocarbon pairs in different solvents and over moderate temperature ranges (to 100°C), a linear dependency of log S°12 on (1/T) can be assumed (12, 14, 26). An example is shown in Figure 5, where log S° for the hexane-benzene pair in five different solvents is plotted against the reciprocal absolute temperature. The relationship can be considered linear for engineering applications. Selectivity decreases with increasing temperature, and this explains the unusual maximum in the variation of selectivity with solvent concentration shown by the system ethylbenzene-ethyl cyclohexane with hexyleneglycol as solvent (Figure 3). 

See Valeraldehyde hexyleneglycol acetal Pentyl isovalerate. See Amyl isovalerate Pentyl mercaptan n-Pentyl mercaptan. See 1-Pentanethiol... 

Undecylenic acid n-Valeraldehyde Valeraldehyde hexyleneglycol acetal n-Valeric acid y-Valerolactone Vanilla (Vanilla planifolia) tincture Veratraldehyde Verdyl acetate p-Vinylphenol 2,3-Xylenol 2,5-Xylenol 2,6-Xylenol Zingerone fragrance, cough drops Menthol... 

Valeraldehyde hexyleneglycol acetal 54549-25-6 Decyl glucoside Oramix NS 10 Plantacare 2000 Plantacare 2000 UP 54571-67-4 Sodium PCA (DL)... 

Roy and Brown examined the rates and equilibrium compositions resulting from the reaction of the cyclic, unhindered phenylboronic ester 2-phenyl-l,3,2-dioxaborolane (A), with several 1,2- and 1,3- diols of various structural types (Scheme 3.1). The equilibrations are rapid (<0.1 h) in CDCI3 at 25 °C. From the equilibrium ratios in Scheme 3.1 it is obvious that six-membered dioxaborinanes are more stable thermodynamically than five-membered dioxaborolanes, and also that introduction of methyl substituents at the a position from oxygen stabilizes the cyclic esters. The very fast and complete displacement by diethanolamine is also worth noticing. Unfortunately, hexyleneglycol was not introduced in this study. 

Many reactions of these boronic esters will involve in the first step a nucleophilic addition onto the boron atom, leading to a tetrahedral boronate anion. With a borolane, this would involve a decrease of the ring strain, and would be kineti-cally more favorable than with the corresponding borinane. Nevertheless, steric hindrance by the a methyl substituents will also be important. This is consistent with the work of Bowie and Musgrave, who compared the rates of hydrolysis of phenylboronic esters exposed to a water-saturated atmosphere, and found that unsubstituted phenylborolane was hydrolyzed faster than unsubstituted phenylborinane. Under the same conditions, phenylboronic esters of pinacol, neopentylglycol and hexyleneglycol were unaffected for several days. 

Boric esters of hexyleneglycol can be prepared in one step by reaction of the diol with one equivalent of boric acid, followed by esterification with an alcohol with azeotropic removal of water. The common esters MeOBhg, EtO-Bhg, PrOBhg and "BuOBhg are commercially available. 

Various hexyleneglycol alkenylboronic esters were engaged in the dimethylzinc-promoted alkenylation of nitrones and synthetically useful yields of the corresponding allylic hydroxylamines were obtained. Selected examples are presented in Table 3.4. 

Table 3.4 Examples of products obtained from the dimethylzinc-promoted alke-nylation of nitrones with hexyleneglycol alkenylboronic esters. "...

Suzuki-Miyaura Couplings with Hexyleneglycol Arylboronic Esters... 

Table 3.6 Examples of Suzuki-Miyaura couplings with hexyleneglycol arylboronic esters.

Blandin and Chavant discuss the use of boronic esters, other than pinacol, for use in cross-coupling reactions. They have identified an interesting alternative to the typical approaches that use hexyleneglycol, resulting in significant advantages that are discussed in detail in their chapter. 

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