Dihydrocholesterol

Fig. IV-19. Fluorescence micrographs showing the shape transitions in monolayers of dimyristoylphosphatidylcholine (DMPC) (84%) and dihydrocholesterol (15%) and a lipid containing the dye, Texas Red. (From Ref. 228.)...

A SOLUTION of 50 g. of dihydrocholesterol(o.i3 mole) (Note i) in 50 cc. of benzene is added slowly with cooling (Note 2) to a solution of 68 g. (0.23 mole) of crystalline sodium dichromate, 50 cc. of glacial acetic acid, and 90 cc. of concentrated sulfuric acid in 300 cc. of water in a 3-I. flask. The mixture is agitated thoroughly in a shaking device or by efiicient stirring (Note 3) for six hours at 25-30° (Note 4). 

Dihydrocholesterol has been prepared by the reduction of cholestenone with sodium and amyl alcohoP and by the hydrogenation of cholesterol. In the presence of platinum black or platinum oxide, yields varying from 6.5 per cent to 40 per cent have been obtained in ether, acetone, ethyl acetate, and acetic acid. ... 

Ultraviolet light causes a chemical change in dihydrocholesterol to produce cholecalciferol, a precursor of vitamin D. The latter conforms better to the definition of a steroid hormone than a vitamin. Indeed, the classification of vitamin D as a vitamin is an historical accident. The precursor is released from the skin and is further modified in the liver and kidney to form dihydroxycholecalciferol, which is the active form of the hormone (see Chapter 15 for the reactions). It increases calcium absorption from the... 

To a solution of 0.200 g. (0.515 mmole) of dry dihydrocholesterol (Note 1) in 10 ml. of methylene chloride contained in a 50-ml. Erlenmeyer flask is added 0.3 ml. of a catalyst stock solution containing 0.0016 ml. (0.018 mmole) of concentrated fluoboric add (Note 2) in 3 1 anhydrous diethyl ether-methylene chloride (Note 3). The solution is swirled, and a 0.451/ solution of diazo-methaue (Note 4) in dry methylene chloride is added from a buret (Note 5) at a rate of about 2 ml. per minute. The yellow color of diazomethane disappears rapidly on contact with the reaction mixture and nitrogen is vigorously evolved. When about 3 ml. of diazomethane solution has been added, the reaction becomes sluggish. The yellow color persists for several minutes after the total amount of 3.9 ml. of diazomethane solution (1.76 mmoles) has been added (Note 6). After 1 hour the reaction mixture is filtered to remove a small amount of amorphous polymethylene, which is washed with methylene chloride. The washings are combined with the methylene chloride solution, washed with 5 ml. of saturated aqueous sodium bicarbonate, with three... 

The analysis of lanolin has concentrated on the lanolin alcohols (the unsaponifiable fraction of lanolin) and lanolin acids produced by hydrolysis rather than the esters in lanolin itself.20 Lanolin alcohols belong to three major groups (1) 69 aliphatic alcohols from C12 to C36, (2) sterols (cholesterol and dihydrocholesterol), and (3) trimethyl sterols (lanesterol, dihydrolanesterol, agnosterol, and dihydroagenosterol).21 The latter have been incorrectly termed triterpenoids. The relative proportion of each group is 22% (w/w) aliphatic alcohols, 35% (w/w) sterols, and 38% (w/w) trimethyl sterols.8... 

Detection limit obtained in mass spectrometry in the case of dihydrocholesterol. 

Olefinic alcohols react smoothly with hydrogen over platinum oxide catalyst at room temperature. The procedure is illustrated by the preparation of dihydrocholesterol from cholesterol. Cinnamyl alcohol. CjH5CH = CHCH20H, is reduced to dihydrocinnamyl alcohol by lithium aluminum hydride. The reduction of allyl alcohol to n-propyl alcohol by the reagent, however, is unsatisfactory, ... 

Another catalyst for the dehydrogenation of alcohols by carbonyl compounds is Raney nickel, which is used to convert dihydrocholesterol into 3-cholestanone in 80% yield by refluxing for 24 h with cyclohexanone in toluene [961]. 

By substituting the cholesterol moiety by dihydrocholesterol, the range of reflection wavelengths can be extended to the IR. Right handed materials were obtained by using doristerol derivatives instead of cholesterol compounds [16]. 

It was found that the presence of cholesterol markedly influences the hydrogenation of mixed phospholipid dispersions [12] because it restricts partition of the catalyst into the lipid bilayer structure. It was also found that no dihydrocholesterol forms during hydrogenation of the phospholipid, showing that cholesterol is not a substrate for reaction under the conditions employed. 

Sec. alcohols, can be oxidized to ketones with Raney-Ni and a H -acceptor carbonyl groups and carbon double and triple bonds can be reduced with Raney-Ni and a H2-donor. The hydrogen adsorbed by the Ni may be sufficient for the reduction, so that the addition of a H2-donor is not necessary.—E Dihydrocholesterol refluxed with cyclohexanone as H2-acceptor in toluene in the presence of Raney-Ni with vigorous stirring for 24 hrs. —cholestanone. Y 80%.—Anisyli-dene-p-methoxyacetophenone and diethylcarbinol as H2-donor refluxed in toluene in the presence of Raney-Ni for 24 hrs. - >- l,3-bis-(p-methoxyphenyl)propane. Y 80%. (F. e. s. E. C. Kleiderer and E. C. Kornfeld, J. Org. Chem. 13, 455 (1948).)... 

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