Alcohol systems

Both high bulk and surface shear viscosity delay film thinning and stretching deformations that precede bubble bursting. The development of ordered stmctures in the surface region can also have a stabilizing effect. Liquid crystalline phases in foam films enhance stabiUty (18). In water-surfactant-fatty alcohol systems the alcohol components may serve as a foam stabilizer or a foam breaker depending on concentration (18). 

Equation (3-178) suggests that a plot of A obs/[ROH] vs. [N] will be linear. Because the conversion to the intermediate is quantitative, [N] = [N]o — [AXJq. Plots according to Eq. (3-178) were linear, permitting ky and A in to be estimated. Turning to the acetic anhydride—alcohol system, it is inferred that (in the absence of water) itj/lLi is close to zero (Scheme XXIV). Although the intermediate could not be detected spectrally, its possible presence is admitted in the rate equation for the loss of anhydride ... 

Table 2. The values of log 1 / Kd and log Pe at 25 °C, together with Es and Emin, for cyclodextrin-alcohol systems...

These equations show that hydrophobic and steric (van der Waals) interactions are of prime importance in the inclusion processes of cyclodextrin-alcohol systems. The coefficient of Es was positive in sign for an a-cyclodextrin system and negative for a P-cyclodextrin system. These clear-cut differences in sign reflect the fact that a bulky alcohol is subject to van der Waals repulsion by the a-cyclodextrin cavity and to van der Waals attraction by the p-cyclodextrin cavity. 

Matsui75) has computed energies (Emin) which correspond to the minimal values of Evdw in Eq. 1 for cyclodextrin-alcohol systems (Table 2). Besides normal and branched alkanols, some diols, cellosolves, and haloalkanols were involved in the calculations. The Emi values obtained were adopted as a parameter representing the London dispersion force in place of Es. Regression analysis gave Eqs. 9 and 10 for a- and P-cyclodextrin systems respectively. 

As a solid dissolves in a liquid, atoms or molecules leave the solid and become part of the liquid. These atoms or molecules may carry no charge (then they are electrically neutral) or they may be ions. The iodine-alcohol system is of the... 

To summarize our effort, we found that C0/H20/K0H systems converted Illinois No. 6 coal to a material which was fully pyridine soluble, 51% benzene soluble, and 18% hexane soluble. As with the basic alcoholic systems, there were significant reductions in organic sulfur levels, and moderate reductions in nitrogen levels. 

The chemistry here is similar to that for the basic alcoholic systems, but with formate (HC02 ) as the hydride-donor, and thus the reducing agent. In control runs with H20/K0H or C0/H20, little or no conversion was observed. 

To show you that all this really does work, I ve listed the experimental composition data for the isopropyl/isobutyl alcohol system from Landolt-Bornstein (Landolt-Bomstein is to physical chemistry what Beilstein is to organic. And wouldn t that make for a wild analogy question on the college board entrance exams ), along with my calculated data (Table 2) (That explains my choice of temperatures for Table 1.). I ve also given the absolute and percent differences between the experimental data, and what I ve calculated. These differences are on the order of 1% or less, a very good agreement, indeed. 

Fig. 140 Temperature-mole fraction diagram for the isobutyl-isoropyl alcohol systems.

Go back to the temperature-mole fraction diagram for the isopropyl alcohol-isobutyl alcohol system (Fig. 140). The composition of the vapor is always different from that of the liquid, and we can separate the two compounds. If the composition of the vapor is the same as that of the liquid, that separation is hopeless. Since we ve used the notions of an ideal gas in deriving... 

As became obvious in the preceding section, progress in understanding alcohol clusters very much depends on the ability to generate these clusters in supersonic jet expansions or in other variants of low temperature isolation and to detect their dynamics via spectroscopic methods. Therefore, some important spectroscopic tools employed in this field shall be summarized, with focus on the alcoholic systems that have been addressed by them. Solution [22, 26, 141, 142] and supercritical [24 26] state techniques will not be covered systematically. 

The reaction between an isocyanate and an alcohol to form a carbamate or urethane has been known for many years but has been applied to the poly(vinyl alcohol) system only recently. This is due largely to the fact that the heterogeneous reaction between PVA and an isocyanate is difficult to control reproducibly. 

Alcohols, their corresponding olefins and alkyl cations are in equilibrium, with the alcohol generally predominating over the olefin (Purlee et al., 1955 Taft and Riesz, 1955 Boyd et al., 1960). The alkyl cation concentration is extremely low and this species never exists as more than a transient intermediate whose relation to the solvent is little known. In 5% H2SO4 the ratio of alcohol to olefin is about 1200 to 1 at 50° for the isobutylene-tertiary butyl alcohol system (Taft and Riesz, 1955). As the temperature increases the ratio of alcohol to olefin at equilibrium decreases (Boyd et al., 1960). This can be illustrated by examining the position of equilibrium in equation (8). Values of Kp, [alcohol (1)]/ [olefin (g)], were shown to vary from 5 54 at 50° to 1-34 at 70°. The equilibrium constant [alcohol (l)]/[olefin (1)] can be calculated from... 

Lee and Meisel incorporated Py, at levels of 10 M or more, into 1200 EW acid form samples that were swollen with water and with ferf-butyl alcohol. It was concluded based on the /3//1 value for water swollen samples that the Py molecules were located in the water clusters and were most likely near fluorocarbon—water interfaces. It was also concluded, based on both absorption and emission spectra, that the probes had strong interactions with the SO3 groups that were exchanged with Ag+ and Pb + cations in the case of water containing samples. Likewise, the pyrene molecules were rationalized as being surrounded by terf-butanol molecules in that case. However, excimer formation (due to the presence of adjacent pyrene molecules) in the ferf-butyl alcohol system suggested the loss of cluster morphology-... 

De Santis, R., Marrelli, L., and Muscetta, P.N. Liquid-liquid equilibria in water-aliphatic alcohol systems in the presence of sodium chloride, Chem. Eng. J., 11 207-214, 1976. 

Multifunctional initiators made up of metal alkoxides rather than alcohols have been less used for the synthesis of star-shaped polyesters than have the tin (II) bis-(2-ethylhexanoate)/alcohol system. Nevertheless, Kricheldorf initiated the polymerization of sCL using a spiro-cyclic tin(IV) aUcoxide to obtain a tin-containing height-shaped polyester whose final hydrolysis resulted in the formation of a star-shaped polyester (Fig. 35) [25, 159-161]. 

Libiszowki J, Kowalski A, Duda A, Penczek S (2002) Kinetics and mechanism of cyclic esters polymerization initiated with covalent metal carboxylates, 5. End-group studies in the model E-caprolactone and L,L-dilactideAin(II) and zinc octoate/butyl alcohol systems. Macromol Chem Phys 203 1694—1701... 

P.W. Collins, R.L. Shone, A.F. Gasieski, W.E. Perkins, R.G. Blanch , Stabilization of a prostaglandin tertiary allylic alcohol system by fluorine Synthesis, acid stability studies and pharmacology of a 16-fluoromethyl analog of SC-46275, Bioorg. Med. Chem. Lett. 2 (1992) 1761-1766. 

In Table 1, we have recorded the yields of fragment nitrosamine produced when the B-hydroxynitrosamine is treated with potassium t-butoxide in tetrahydrofuran (THF) at 70° (5). Reported yields are by no means maximal and the conditions were chosen so that we could compare the rates of cleavage of a number of different B-hydroxynitrosamines. By using an appropriate alkoxide-alcohol system, a nearly quantitative yield of fragment nitrosamine can be produced in this retroaldol type cleavage reaction. 

Najdanovic-Visak, V. et al.. Pressure, isotope, and water co-solvent effects in liquid-liquid equilibria of (ionic liquid + alcohol) systems, /. Phys. Chem. B, 107, 12797, 2003. 

Porphyrin-Alcohol Systems in the Presence of a Lewis Acid. 88... 

This section describes the Lewis acid promoted immortal polymerization of epoxide by aluminum porphyrin-alcohol systems in the presence of an orga-noaluminum accelerator. 

We have made a quantitative investigation of the spectra of methanol, ethanol and 6-butanol over rather wide temperature and concentration ranges ( —15° to + 60°C, and 0 005 to 1 M) in order to obtain more precise information as to the spectral and thermodynamic properties of the alcohol systems. We are particularly interested in establishing such properties for a single specific species, the dimer. 

The NIPA gel has a molecular structure which contains not only hydrophilic (NH, C=0) but also hydrophobic (isopropyl) groups. Recently, Hirotsu [8] investigated the phase transition behavior of NIPA gel/water/alcohol systems and explained the thermoshrinking by the destruction of hydrogen bonds between water molecules and amino or carbonyl groups. However, Ulbrich and Kopecek [9] pointed out the importance of hydrophobic interactions in then-study on the mechanical properties of N-substituted acrylamide gels. 

Fairly selective reduction of certain alkenes can be achieved using the sodium-hexamethylphosphoramide (HMPA)-tm-butyI alcohol system,193 despite the general trend, that nonconjugated alkenes are usually quite resistant to the dissolving metal reduction method (see Section 11.3.2). In the case of 9(10)-octalin, the transformation leads to a nearly equilibrium product distribution ... 

Mesostructured aluminophosphate / surfactant composite materials were prepared from aqueous and alcoholic systems. Syntheses in ethanol or methanol, respectively, lead to mixtures of two nanostructured phases. One of these consists of hexagonally arranged rod-like assemblies of the surfactant molecules with the head groups located in the centres, encapsulating the inorganic aluminophosphate the other is lamellar. The syntheses were monitored by in-situ temperature- and time-resolved small angle X-ray scattering (SAXS). 

In conclusion, the synthesis of mesostructured aluminophosphate / surfactant materials in alcoholic systems yields a mixture of an inverse hexagonal and a lamellar phase, the latter of which is more stable, as its formation is relatively favoured by higher temperatures and/or longer reaction times. The synthesis is highly cooperative the surfactant / alcohol systems without the inorganic species do not show any lyotropic behaviour. 

The first example of kinetic resolution catalyzed by an organometallic compound was the partially enantiomer-selective polymerization of racemic propylene oxide induced with a diethylzinc optically active alcohol system (50). 

C is-fused tetrahydrofurans are produced when 2-cycloalkenyl-substituted ethanol derivatives are cy-clized via 5-exo ring closure (equation 14 and Table 5). The related 1-cycloalkenyl alcohol systems also yield cri-fused tetrahydrofurans upon reaction with phenylselenyl reagents, similar to their carboxylic acid analogs (see equation 12).60 A sulfoetherification to a fused ring tetrahydrofuran from a system with an exocyclic methylene provided an 86 14 ratio of cis- and frans-fused isomers.61... 

The bromocyclization of A/,jV-dialkylaminomethyl ethers of allyl and propargyl alcohols to form oxa-zolidinium salts has been reported, but not used in synthesis.255 The heterocyclization of /V-acylamino-methyl ethers with mercury salts has been used for stereoselective synthesis of a variety of 1,2-amino alcohol systems. These cyclizations form rans-4,5-dialkyl oxazolidine products with good to excellent stereoselectivities (equation 120 and Table 33). As shown by entry 5, 6-endo cyclization predominates (6 3) with an internal double bond of ( )-configuration, but this mode of cyclization is reduced with substrates containing a (Z) double bond and/or allylic oxygen substitution (Table 33, entries 6-9). 

Compound 8 is a secondary allylic alcohol Systems of this type are well suited to the application of Sha/pless epoxidation 4 for kinetic racemate resolution,5 because the chiral titanium reagent bonds directly with the stcreogenic center (C-9) in the transition state (21). The undesiicd enantiomer epoxidi/es more rapidly than 9, so 9 can be separated in enantioinerically pure form (see Chapter b). 

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