Alcohol cholesteric

As compared to the cholesteric LC, the lyotropic LC consists of two or more components that exhibit liquid-crystalline properties (dependent on concentration, temperature, and pressure). In the lyotropic phases, solvent molecules fill the space around the compounds (such as soaps) to provide fluidity to the system. In contrast to thermotropic liquid crystals, these lyotropics have another degree of freedom of concentration that enables them to induce a variety of different phases. A typical lyotropic liquid crystal is surfactant-water-long-chain alcohol. 

Lanolin and lanolin alcohols are excellent emulsifiers, giving oil-in-water emulsions, and can be combined with additional emulsifiers such as cetearyl alcohol to improve stability.8 The ability of anhydrous lanolin and especially lanolin alcohols to form stable emulsions with up to 300% (w/w) of water distinguishes lanolin from petrolatum in its physical properties.1 The chemical compositions of lanolin and petrolatum are also very different, as petrolatum is composed completely of hydrocarbons.16 Lanolin alcohols and petrolatum can be combined to form cholesterized petrolatum, which also has the capacity to form emulsions. For example, a mixture of 65% (w/w) lanolin, 20% (w/w) water, and 15% (w/w) petrolatum can incorporate an equivalent weight of water without changing its consistency.15,52... 

Throughout this research we have made constant use of columns coated with cholesteric phases (54-55). Thus, for example, asymmetric induction in amide alkylations as well as asymmetric reductions of carbonyl were conveniently judged either on the product directly (amides) or on any of several derivatives of the product (alcohols) with cholesteryl cinnamate as a GLC stationary phase. 

A similar thermally-induced inversion of the cholesteric sense was observed for the PBLG liquid crystal in benzyl alcohol. In this solution, a gel-like opaque phase coexists with the cholesteric phase at lower temperatures. The opaque phase disappears around 70 °C, where endothermic peaks are observed in the differential scanning calorimetry curve. The value of S below 70 °C remains constant, and then changes with temperature above 70 °C. The compensation occurs at about 103 °C, and the transition from biphasic phase to the isotropic phase is observed above 150 °C in this case. The results are summarized in Fig. 12, where the reciprocal of the half-pitch is plotted against temperature. The sign of 1/S is taken as positive when the cholesteric sense is the right-handed. 

Cholesteric alcohol—Cholesterin—CjeHoOH—372—is an alcohol, although usually classed by physiologists among the fats, because it is greasy to the touch and soluble in ether. 

It combines readily with the volatile fatty acids. Prom its solution in glacial acetic acid a compound having the composition Ci H4,0,CjH40a separates in fine curved crystals, which are decomposed on contact with water or alcohol when heated with acids under pressure, it forms true ethers. Hot HNOj oxidizes it to cholesteric acid, CsH,oOk, which is also produced by the oxidation of biliary acids a fact which indicates the probable existence of some relation between the methods of formation of cholesterin and of the biliary acids in the economy. 

Cholesteryl esters (cholesterol esters). As a monofunctional secondary alcohol cholesterol is able to form esters. As lipids these esters are very important for the construction of cell membranes (see cholesterol). Esters of C. with aliphatic or aromatic carboxylic acids are also important as liquid crystals because of their special properties cholesteric phases). 

H. Akiyama, A. Tanaka, H. Hiramatsu, J. Nagasawa, N. Tamaoki, Reflection colour changes in cholesteric liquid crystals after the addition and photochemical isomerization of mesogenic azobenzenes tethered to sugar alcohols. J. Mater. Chem. 19, 5956-5963 (2009)... 

Many works deal with the variation of the helicoidal pitch in cholesteric phases as a function of temperature and composition. The best way to elucidate the origin of the twist seems to be to compare the pitch variations in lyotropic and in thermotropic systems. The first accurate work in this field is due to Robinson (1958-66) who studied PBLG (polybenzyl-L-glutamate) a synthetic polypeptide in organic solvents as dioxane, ethylic alcohol, chloroform etc. and Cano (1967) who made measurements of the pitches of nematic paraazoxyphenetol with different amounts of cholesterol benzoate. 

CAS 57-88-5 EINECS/ELINCS 200-353-2 Synonyms Cholest-5-en-3p-ol 5-Cholesten-3-p-ol Cholesteric esters Cholesterin Cholesteryl alcohol... 

Terpenoids are as unpolar as the steroids, but normally they have bad mesogenic properties. Some unmodified terpenoids like carvon have been used to induce long helical pitches in nematic phases. Esters of menthyl, isopinocampheyl, or other terpenoidal alcohols have been used for cholesteric and ferroelectric phases. 

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