Kofler hot stage

Melting points are uncorrected and were determined with a Kofler hot-stage apparatus. 

IR spectra were recorded on a Perkin-Elmer model 125 spectrophotometer. Melting points were determined on a Kofler hot-stage apparatus and are not corrected. 

The total yield of the crude precipitation obtained in the above manner comprising about 1 kg is then dissolved in chloroform so as to form a 15% solution of a crude penicillin salt. To the filtered chloroform solution is added ethyl acetate slowly and with agitation until the solution becomes turbid as crystallization begins. Thereafter crystallization is allowed to proceed undisturbed for about 30-60 minutes in a cold room having a temperature of about 5°C. Sufficient ethyl acetate is slowly added to provide a final concentration of about 50% ethyl acetate and the mixture is allowed to stand in the cold room for one hour to complete crystallization. The precipitate is filtered and washed with about 750 ml of ethyl acetate and thereafter washed with the same volume of ether. The crystals are dried in vacuo and a yield of about 900 g of N,N -bis-(dehydroabietyl)-ethylenediamine-dipenicillin G is obtained. The penicillin product melts with decomposition at a temperature of 170°C to 172°C on a Kofler hot stage. Solubility analysis of the product shows the product to be 95.3% pure. 

The systematic use of the hot stage microscope employing mainly the Kofler hot stage was originally described in the book by Kofler and Kofler (1954) (the founders... 

Fig. 12.1 Melting point apparatus (a) oil bath (b) heated block - thermometer readout ic) heated block - digital readout (d) Kofler hot-stage microscope.

Kofler hot stage.) Infrared spectra were taken in Nujol mulls on a grating spectrophotometer. 

Melting points taken with Kofler hot stage microscope, or by X-ray techniques. 

Six polymorphic forms of aspirin have been detected using differential scanning calorimetry. A Kofler hot stage was used to confirm the melting points of the polymorphs and to observe solution phase transformations of pairs of polymorphs. Density differences are reported for four of the polymorphs which could be isolated, but only minor variations in X-ray diffraction patterns could be observed. 

Vco 1962 cm-p-FCgH, mp 175-180°, Vcol984cm- . (Melting points uncorrected on Kofler hot stage). Infrared spectra were taken in Nujol mulls on a grating spectrophotometer. 

Optical properties (e.g. light TOA (thermomicroscopy (Kofler hot-stage method). 

Optical rotation was measured at ambient temperature for solution in CHCI3 with a Perkin-Elmer automatic polarimeter. Model 341. Melting point was measured on a Kofler hot stage. Thin-layer chromatography (TLC) was performed on silica gel 60 coated glass slides. Column chromatography was performed by... 

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