Kofler

Retinyl acetate [127-47-9] M 328.5, m 57". Separated from retinol by column chromatography, then crystd from MeOH. See Kofler and Rubin [Vitamins and Hormones (NY) 18 315 1960] for review of purification methods. Stored in the dark, under N2 or Ar, at 0°. See Vitamin A acetate p. 574 in Chapter 6. 

As regards general methods for distinguishing between the alkaloids of opium, mention may be made of the following Kofler and Kofler s study of the micro-sublimation of these alkaloids and the characters of the micro-sublimates the comparison by Maplethorpe and Evers of the picrates of a series of opium bases, comparison of the colour reactions of a series of opium alkaloids, and their behaviour with specific reagents and precipitants. ... 

Rhoeadine crystallises from a mixture of chloroform and ether, sublimes at 215-25" /0-02 mm., and then melts at 256-57-5° (vac.), and has [a] / ° -f 232° (CHClj). According to Awe it has m.p. 272-4° (Kofler s micro-apparatus), and [a]] ° -f 243° (CHClj). A crystalline liydriodide, B. HI. 2H2O, was prepared by the addition of potassium iodide to a solution of the alkaloid in acetic acid. Rhoeadine contains one methoxyl group and a dioxymethylene group, but no reactive hydrogen (Zerewitinoff). 

This product crystallized by dissolving in ether and reprecipitation with petroleum ether yielded 7 g of 1 -phenyl-2-hydroxy-ethylene-cyclohexan-1 -ol, melting point (Kofler) 81°C to 83°C. 

After one day standing in a refrigerator, the product was filtered and washed with water, thus yielding 5 g of 2-phenyl-2-hydroxy-cyclohexane-carboxylic acid, melting point (Kofler) 143°C to 145°C. 

The complex is decomposed by stirring the reaction mixture into a solution prepared from 500 g of ammonium chloride in 2,000 ml of water to which 3 kg of crushed ice have been added. After extraction and washing, the ether is evaporated in vacuo at 40°C. The oily residue is taken up in 500 ml of petroleum ether and left to crystallize by cooling at -20°C. The yellowish crystals formed are dried (309 g) MPi< (Kofler block) 74°C yield 92%. 

The filtrate is evaporated under vacuum and the residue is crystallized from a solution of 60 parts of isopropanol in 75 parts of water. There are obtained 9 parts of N-(3-sulfamyl-4-chlorobenzamido)-2-methyl indoline, MP (K) 184° to 186°C, MP (MK) 160° to 162°C (isopropanol/water). [The melting points being determined on a Kofler heater plate under the microscope (MK) or on a Kofler Bank (K)]. ... 

The mixture was poured in water, acidified to pH 1 with dilute hydrochloric acid, heated on the steam bath for 30 minutes and then subjected to steam distillation to remove the organic solvents. The residue was filtered, dried and recystallized several times from ethyl acetate. The A -19-nor-17a-ethinylandrosten-17/3-ol-3-one thus obtained had a MP of 198° to 200°C (in sulfuric acid bath), 200° to 204°C (Kofler). 

For more precise work, micro hot stage methods under a microscope are used. For all compds, except those which are isotropic or become so on heating, the mp can best be observed by means of a polarizing microscope, since the temp at which color disappears arid the space lattice is ruptured is the true mp. Among numerous models of micro-hot stages, the Kofler micro-hot stage has attained widespread use and is commercially available (Refs 3 4)... 

Kofler Kofler, Thermo-Mikromethoden zur Kennzeichnung Organischer Stoffe , Verlag Chemie, Weinheim/Bergstr (1954)... 

No detailed studies on the crystal structure of methimazole is reported in the literature. Methimazole can be microscopically identified using Kofler s method, the occurrence of polymorphous modification is indicated in methimazole. 

Bernhard D, Ausserlechner MJ, Tonko M, Loffler M, Hartmann BL, Csordas A, Kofler R. (1999) Apoptosis induced by the histone deacetylase inhibitor sodium butyrate in human leukemic lymphoblasts. FASEB J 13 1991-2001. 

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