Heptane, 1,4-dioxane

Sosnowski et al. [124,125] have reported that uniform biodegradable polymeric particles with diameters of less than 5 pm can be prepared by ringopening dispersion polymerization of L,L-lactide in heptane-dioxane mixed solvent in the presence of poly(dodecyl acrylate)-g-poly( -caprolactone), which were synthesized by copolymerization of dodecyl acrylate with poly(e-caprolactone) macromonomers, 46. It is noted that the polymer particles consist of well-defined poly(L,L-lactide) polymers with Mn lxl04 and Mw/Mn 1.06. 

Poly(dodecyl methacrylate)- - e-caprolactone Heptane/dioxane [97,98]... 

Dispersion polymerization has also been applied to the ring opening polymerization of e-caprolactone and lactide in heptane-dioxane (4/1 v/v) with poly(dodecyl methacrylate)-g-poly(e-caprolactone) as stabilizer [97]. Diethyl-aluminium ethoxide and tin(II) 2-ethylhexanoate were used as initiators in these two systems, respectively, to obtain functional microspheres with a narrow particle size distribution and a narrow molecular weight distribution [98]. Table 2 provides an overview of microspheres obtained by living dispersion polymerization. 

Isoamyl acetate Heptane Dioxane Benzene Allyl alcohol... 

Mixture of 1 ml dimethyl phthalate, 1 ml diethyl phthalate, and 1 ml dibutyl phthalate Filled up with n-heptane-dioxane 90 10 to 100 ml Filled up with MeOH-H20... 

Mobile phase n-heptane-dioxane (90 10) Mobile phase MeOH-H20... 

Bile acids can also be converted into phenacyl [81] and p-bromophenacyl [102] esters. A bile acid sample with 50% excess of 0.15 M triethylamine in acetonitrile was warmed briefly and 0.1 M phenacyl bromide (50% molar excess) in acetonitrile was added. The reaction mixhire was maintained at 80—90°C for 45—60 min. The separation of phenacyl esters of lithocholic, deoxy-cholic, chenodeoxycholic, ursodeoxycholic hyodeoxy-cholic and cholic acids was carried out on an ODS column. The excess derivatizing agents and interfering biological compounds from bile samples were first eluted with n-heptane/dioxane (90 10 v/v), and the separation of derivatives of bile adds was accomplished with n-heptane/dioxane/isopropanol (70 25 5, by vol). The detection limits at 254 nm for the derivatives were 5-lOng [81]. 

PB with terminal Heptane / dioxane Lichrospher Si, 500 °A O.lml/min Zero, mono and difunctional Estrin Yal, Kasumova LT [34] ... 

PB n-heptane / dioxane NucleosENHi, 1000°A, 60°C Determination of number of Pulda J, Reisova A [35] ... 

FIGURE 7.10 Strength of polycrystalline sodium chloride specimens as a function of the medium composition in -heptane/dioxane and dioxane/water systems. (Redrawn from Kuchumova, V.M. et al., Kolloidnyi Zh., 69, 357, 2007 Kuchumova, V.M. et al., /. Mater Sci., 27, 5516,1992.)... 

Typical normal-phase operations involved combinations of alcohols and hexane or heptane. In many cases, the addition of small amounts (< 0.1 %) of acid and/or base is necessary to improve peak efficiency and selectivity. Usually, the concentration of polar solvents such as alcohol determines the retention and selectivity (Fig. 2-18). Since flow rate has no impact on selectivity (see Fig. 2-11), the most productive flow rate was determined to be 2 mL miiT. Ethanol normally gives the best efficiency and resolution with reasonable back-pressures. It has been reported that halogenated solvents have also been used successfully on these stationary phases as well as acetonitrile, dioxane and methyl tert-butyl ether, or combinations of the these. The optimization parameters under three different mobile phase modes on glycopeptide CSPs are summarized in Table 2-7. 

Insoluble In acetone, dioxane, alcohols, hexane, and heptane. 

Normal /, /i -Oxydipropionitrile Carbowax (400, 600, 750, etc.) Glycols (ethylene, diethylene) Cyanoethylsilicone Saturated hydrocarbons, e.g. hexane, heptane aromatic solvents, e.g. benzene, xylene saturated hydrocarbons mixed with up to 10 per cent dioxan, methanol, ethanol, chloroform, methylene chloride (dichloromethane)... 

Solvent effects on the rate of the decarbonylation of MeCOMn(CO)5 were examined by Calderazzo and Cotton (50) and are presented in part in Table IV. In general they are very small, and no regular trends can be discerned. This virtual lack of dependence of the rate on the nature of the solvent and very little correlation between the rate and the dielectric constant of the solvent are typical of substitution reactions of metal carbonyls (J). In the light of the foregoing, a qualitative observation that CpFe(CO)2-COMe decarbonylates much more readily on treatment at reflux in nonpolar heptane or cyclohexane than in polar dioxane is somewhat intriguing 219). 

Continuous Experiments with Thermomorphic Systems. For the continuous experiments, we used the best solvent system we identified in the batch reactions, which was 50 50 1,4-dioxane/water. Heptane was the nonpolar solvent and CTAB the surfactant. We chose this system over the 50 50 ethanol/water system because it gave us better selectivity and there is no chance that unwanted acetal side products will be formed by the reaction of ethanol with the aldehyde. We initially used 1-octene as the olefin and after we worked out the process conditions for 1-octene, we tested the higher olefin 1-dodecene. 

As an example, Table 20.2 lists the rate of the racemization of 61 via an MPVO procedure utilizing the catalyst neodymium(III) isopropoxide (62) as a function of the solvent. In this case, an equimolar amount of acetone was applied as the oxidant. The best results were obtained with hydrocarbons such as hexane (entry 7) and heptane (entry 8) as solvents, while the reaction rates in dioxane (entry 2) and acetonitrile (entry 1) were much lower due to inactivation of the catalyst by coordination of the solvent to the metallic center (Table 20.2) [84]. 

The ability to cyclize to a phenanthrene has been employed in analytical procedures for tamoxifen (69). The drug was irradiated at 254 nm in dioxane-heptane solution and the assay based on the fluorescence of the product (70) [57]. Another group ran the tamoxifen on a TLC plate which was exposed to a UV lamp for some minutes before assaying in a densitometer [58]. 

Here as well as for lg(k), the exclusion of the most deviating data for one of solvents -acetone for AG, heptane or dioxane for E Act and AH, and benzene or heptane for AS allows to receive equations with R > 0.99. For majority of activation descriptors the polarizability as fi(n2) is least meaningful factor exception AS where is 82 also, as and for lg(k). However its exclusion decreases R from 0.95 to 0.93, that undesirable according to [6], The exclusion of other parameters from equation is more noticeable. 

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