Cholesteryl chloride

For CD observation, pyrene-2-carboxylic acid methyl ester was dissolved into a cholesteric mixture of 55.5 mole percent of cholesteryl nonanoate and 44.5 mole percent of cholesteryl chloride, which exhibited a pitch band CD with plus sign... 

Cage effect measured by quenching of the escape radicals with CuCl2. Cholesteryl chloride/cholesteryl nonanoate, 35/65, w/w. 

The experimental values found for all the methyl carbons in 3-methyl-5,6,7,8-tetrahydro-quinoline [162], 8,9,9-trimethyl-5,8-methano-5,6,7,8-tetrahydroquinazoline [162], and cholesteryl chloride [166] may be cited as examples. Lower intensities and longer T, values relative to the methylene and methine carbon nuclei thus frequently facilitate detection of methyl resonances in 13C NMR spectra. 

In the side chain of cholesteryl chloride C atoms with the same number of attached protons are found to behave similarly [166] the methyl carbon atoms C-26 and C-27 relax more slowly than C-21, the methylene carbon C-24 slower than C-23, and the methine carbon atom C-25 slower than C-20. The mobility of the side chain thus increases with increasing distance from the steroidal skeleton. 

Spin-lattice relaxation (f) times. The information deduced from measurements of spin-lattice relaxation times of steroids [166, 570, 576, 577] is discussed in detail in Section 3.3.3, in which the f values for cholesteryl chloride [166] are given as an example. 

In 1946 Shoppee noted that the reaction of 3- -cholesteryl chloride with acetate ion proceeds entirely with retention of configuration (Equation 6.29). Substitutions on the analogous saturated compound proceed with the expected... 

Cholesteryl oleate (CO Aldrich, 97%) contained impurities which absorb strongly below 320 nm. Even after purification (see below) it developed extraneous absorptions unless stored and handled in the absence of air and below room temperature. The purification procedure has been described (10). The Isolated material exhibited an enantlotropic phase (T +c 41-42°C and Tc+i 55.0°C [lit (24) mp 50.5°C]) and no discernible absorption above 300 nm. Cholesteryl chloride (CC1) from Aldrich was recrystallized from 95% ethanol, mp 96.5-99°C (lit (9) 95-96°C). 

The first measurement of steroid 13C Tx values was reported (31) for cholesteryl chloride in 1 m carbon tetrachloride at 42 °C using the conventional 180°-r-90° inversion-recovery technique. The values obtained are given in Fig. 2. 

FIG. 2. Carbon relaxation times (s) for 1 m cholesteryl chloride in carbon tetrachloride. (31)... 

Positive Cotton effects (c.d.) are reported for both 3a- and 3/8-trimethylstannyl-5a-cholestanes, at 203 nm and 210 nm, respectively.35 The compounds were studied in connection with an evaluation of the effects of /3 -trimethylstannyl substituents in cyclohexanone analogues, which provide evidence of through-bond coupling to augment that already recognized for electronegative substituents.36 The circular dichroism associated with the enone systems of cholest-4-en-3-one and 3/3-acetoxycholest-5-en-7-one has been recorded for samples oriented by an electrical field in a nematic phase composed of cholesteryl chloride and cholesteryl laurate.37 New rules are proposed for the correlation of D-Iine molecular rotations with structures of steroid derivatives.38 This work extends an earlier analysis39 and in the present case relates mainly to data for substituents at C-3, C-5, and C-6. 

The first prototype chiral nematic phase change devices were demonstrated with a tertiary mixture of cholesteryl chloride (12), nonanoate (13) and oleyl... 

Figure 4.6-8 Optical rotation exhibited by a 0.2 mm thick sample of a mixture of cholesteryl chloride and cholesteryl myristate (molar ratio 1.67) at 1900 cm Scanning the temperature changes the pitch. At 59.5 °C the pitch corresponds to 1900 cm , at about 48 °C the twisting influences of the mixture components are mutually compensated so that the sample is nematic, at lower temperatures the structure is countercurrent. Above and below T em the rotatory dispersion follows a curve as derived by de Vries (1951).

Chlorination of steroids. Chlorination of cholesterol wi this reagent gives cholesteryl chloride, with the usual retention of configuration shown by A -3/3-ol steroids in displacement reactions. However in other cases, the chlorination is effected with an unusual stereospeciflcity. Inversion of configuration obtains when the OH group is equatorial, but substitution with retention obtains when the OH group is axial. Thus 3a- and 3 8-hydroxysteroids are converted to the same product. Examples ... 

Figure C.4. Molecular structures of (a) cholesterol nonanoate (ChNon) and (b) cholesteryl chloride (ChQ). Pure cholesterol has the structure of cholesteryl chloride with the -Cl replaced by a -OH group.

While you will synthesize and characterize cholesterol nonanoate, you will actually study mixtures of two liquid crystalline materials each of which is a derivative of cholesterol. The other derivative is cholesteryl chloride (ChCl) whose structure along with that of cholesterol nonanoate is shown in Figure C.4. The reason to study mixtures here is for convenience of handling. Though both pure materials exhibit liquid crystalline phases (ChNon at 74" C, solid smectic 80°C smecticicholesteric 93" C cholesteric isotropic, and ChCl about 70 "C, solid cholesteric), appropriate mixtures are liquid crystalline at much lower and more manageable temperatures, for example, room temperature. 

Cholesterol 57-88-5 Dry nonanoyl chloride 764-85-2 Cholesteryl chloride 910-31-6 Reagent acetone 67-64-1 1M sulfuric acid 7664-93-9 Dry pyridine 110-86-1... 

As mentioned above you will be studying mixtures of cholesteryl nonanoate and cholesteryl chloride rather than the pure materials. Mixtures are used for the convenience of working at temperatures closer to room temperature. To prepare a mixture of a given composition, use the mole fraction composition scale. A mole fraction of a component in a mixture is defined as the number of moles of that component in the mixture divided by the total number of moles of all components in the mixture. To actually prepare a mixture, add the desired amounts of each component to a screw cap vial. Mix the components physically with a spatula to make a reasonably uniform mixture of the solids. Place the vial in a sample oven whose temperature has been set to about 100°C and allow the solids to melt and mix. 

C26H5206 tetraethyiene glycol monostearate 106-07-0 15.00 1,1285 1 34518 C27H45CI cholesteryl chloride 910-31-6 25.00 0.9288 2... 

While the above process is irreversible, trans - cis conversion of azobenzene in the mixtures of cholesteryl chloride and its nonanoate causes reversible shift of the cholesteric reflection wavelength (21). When azobenzene is chemically bonded to cholesteryl moiety, the same phenomenon was observed (22). 

Determination of spin-lattice relaxation times also aids chemical shift assignments (vide supra). The more rapid reorientation of the methyl group in cholesteryl chloride with respect to the whole molecule, for example, results in a markedly longer relaxation time than that observed for the carbon atoms constituting the steroid skeleton (Allerhand et al., 1971b). 

Looking back, the earliest written report concerning the possibility of having a smectic phase with twisted layers comes from the work of Wolfgang Ullrich Muller at the Technischen Universitat Berlin in 1974 [40], In his thesis entitled Verhalten cholesterischer Mesophasen unter dem Einfluss von Phasenum-wandlungen , Muller examined the mesophase behavior at the chiral nematic to smectic transition for various mixtures of cholesteryl oleoyl carbonate (COG), 5, and cholesteryl chloride (CC), 6. Muller came to the conclusion from his work that the smectic phase must have a helical structure and that the heli-axis must lie in the plane of the layers, and the structure must also have... 

Fig. 4.1.5. Reflexion spectrum from a monodomain cholesteric film at normal incidence. Full curve experimental spectrum for a mixture of cholesteryl nonanoate, cholesteryl chloride and cholesteryl acetate in weight ratios 21 15 6 at 24 °C (intensity in arbitrary units). Broken curve spectrum computed from the exact theory for a film thickness of 21.0 ftm and pitch 0.4273 foa. (After Dreher...

Fig. 4.1.16. Variation of inverse pitch with temperature in a 1.75 1 weight mixture of right-handed cholesteryl chloride and left-handed cholesteryl myristate as determined by laser diffraction. The mixture becomes nematic at 42 °C. (Sackmann...

Sackmann et have investigated the temperature variation of the pitch of a mixture of right-handed cholesteryl chloride and left-handed cholesteryl myristate by this method. At a certain temperature (7 ) there is an exact compensation of the two opposite helical structures and the sample becomes nematic. At this temperature only the central spot (zero order) is observed, while at the other temperatures, polarized diffraction maxima of higher order make their appearance. The inverse pitch varies almost linearly with temperature passing through zero at 7 (fig. 4.1.16). 

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