Activity grades

Diehloromethane was purified by percolation through Woelm activity grade 1 basic alumina and stored under nitrogen. 

A solution of 5 g (14 mmoles) of 5a-cholest-2-ene in 100 ml ethyl acetate and 8 ml of 2.8 M (22 mmoles) cyanogen azide (CAUTION See Chapter 15 and ref. 139b) in ethyl acetate is heated at 50-53° for 24 hr, during which time about 22 mmoles of nitrogen is evolved. Solvent is removed by evaporation and the residue is applied in benzene to a column of 160 g of neutral alumina (activity grade III). Elution with petroleum ether-benzene (1 1) gives 1.6 g of... 

Activity grade I, neutral alumina was supplied by Brinck-mann Instruments, Inc., Westbury, New York. The checkers used a 3x30 cm. column. 

Activity III alumina is prepared by adding 6% (w/w) of water to neutral alumina of activity grade I. The submitters used a 50x3 cm. glass column for the chromatography. 

Anhydrous sodium sulfate, special grade Sodium hydroxide (Na OH), special grade Hydrochloric acid (HCl), special grade Aluminum oxide 90, neutral, activity grade II-III (Merck)... 

The resulting dry LSD base is chromatographed on basic alumina (activity grade 1) as previously described. The blue band is collected as before, evaporated and converted into the tartrate salt. The iso-LSD band may be collected and saved for further re-cycling. 

Aluminium oxide (neutral, activity grade I) available from M. Woelm, Eschwege, Germany, was deactivated by the addition of 7 ml. of water to 1 kg. of the adsorbent before use. 

Brockmann alumina, activity grade II-III, M. Woelm, 344 Eschwege, West Germany. 

All the reagents used are analytical grade, commercially available products, which are used without further purification. Darkened benzoquinone was purified by sublimation. Activated grade manganese dioxide was used however it was not shown that "activation" of manganese dioxide is necessary for the reaction. 

Purification of the extract hy filtration through a column with aluminium oxide (activity grade II)... 

Column chromatography utilized 63 to 200 pm of silica gel and 63 to 200 /an of neutral alumina activity grade 1. Melting points are all recorded in air in a well-ventilated hood, and are uncorrected. The reactions are all routinely monitored by infrared (IR) spectroscopy using a 0.05-mm pathlength cell. 

Dimethylsulfoxide is purified by filtration through a 2 x 25 cm chromatographic column filled with alumina (activated grade I, neutral, 150 mesh), under a nitrogen atmosphere. This procedure of purification of the solvent is crucial to obtain the indicated yield, since on use of distilled or commercially available anhydrous dimethylsulfoxide, extensive decomposition takes place. 

The product is 97-98% pure by g.l.c. (Note 6) and is satisfactory for most purposes. If desired the adamantanone may be purified by either column chromatography (alumina, activity grade IV eluent ether) or by treatment with fuming sulfuric acid (20% free sulfur trioxide). For example 8.0 g. of adamantanone is added portionwise to 40 ml. of ice-cold fuming sulfuric acid. Then the solution is heated to 40° and maintained at this temperature for one hour. After pouring the mixture onto ice, the adamantanone is recovered by extraction with methylene chloride. 

The dimer-rich fractions were adsorbed on 30 parts of Woelm alumina, activity grade IV (i.e., alumina containing 10% water) and eluted first with mixtures of chloroform and cyclohexane and on a second pass with benzene and cyclohexane. Occasionally, acetone-cyclohexane mixtures were used for better separation of alcohols and dimers and nylon powder chromatography for ultimate purification. Even at a 30 1 (alumina lignin) weight... 

It should be noted that the resolution obtained on a t.l.c. plate is rather better than would be obtained on a conventional adsorption column (see however other column techniques below) and hence further trials should be made with the various activity grades and with controlled solvent composition changes before the bulk of material is submitted to this type of separation. It is in these trials that careful attention to the chromatographic profile obtained from suitable analysis of the eluate fractions, and to the total recovery of material from the column, is so important. 

Notes. (1) The success of the dry-column technique for the resolution of mixtures is completely dependent on the use of the correct activity grade of adsorbent. It should not be assumed that the grade purchased is activity I, to which the appropriate amount of water could be added (see earlier). It is therefore essential to determine the activity by the use of the method previously described, or by using the elegant micro-method described by Loev and Goodman in their definitive paper. 

Water Added (w/w%) Activity Grade Azobenzene Number (Maximum Adsorption of Azobenzene, 10-5 mol/g) R, (p-Amino-Azobenzene)... 

Column design and preparation incorporated previously described methods reported in the literature (39). Two different adsorbents were employed a 100/120 mesh crosslinked styrene/ divinylbenzene resin (Polypak P-Waters Associates) and a Woelm aniontropic activity grade alumina. These adsorbents were packed in 300 and 94 cm. stainless steel columns having a 1 mm. internal diameter. Pressure drop across the adsorbent bed was kept to a minimum (<0.02 atm.) by using a heated pressure reduction valve at the end of the column. Typical linear flow velocities through the columns were in the range of 0.27-2.17 cm/sec. 

---