Pouring procedures layer preparation

A strip of adhesive tape (Tesafilm, Scotch tape), 1—2 cm wide, is stuck all round the outside of the plate to be able to prepare thicker layers on glass plates, using the pouring procedure. The adsorbent suspension is poured into the shallow trough thus formed. The adhesive strip can be torn off after the layer has dried. 

The layers are best prepared by the standard procedure, using a spreader (p. 56, 85). Pouring procedures are used successfully in many... 

The general procedure for the electrochemical preparation of (10) is as follows. A solution of (9) (3 mmol) in wet acetonitrile (40 ml, 5 vol.% of H20) containing sodium perchlorate (0.25 m) was placed in an undivided electrolysis cell equipped with a platinum plate anode and a platinum plate cathode. The system was subjected to a constant current electrolysis (300 mA current density, 20mAcnr2) at ambient temperature. After 4 faradays per mole of (9) had been consumed, the electrolysed solution was poured into water (50 ml) and extracted with dichloromethane (3 X 30 ml). The organic layer was dried with magnesium sulfate and concentrated under reduced pressure. The residue was chromatographed on silica gel to afford (10) in an excellent yield. 

The same procedure as for the pn bromide (No. 108 c) Is used to prepare this compound, except that 26.5g of dpn are substituted. Two hours of oxidation in air is sufficient. The deep yellow-brown liquid is allowed to evaporate spontaneously in an open dish for two days and is then poured into 400ml of acetone. The oily lower layer is poured into a large mortar and triturated with successive portions of fresh acetone until a yellow powder remains. This is brought onto the filter with the same solvent and transferred while still moist to a vacuum desiccator. 

A solution of pyridine in HF was prepared according to Olah s procedure." In a mixture of 70% HF/ pyridine (2 mL) and Ei,0 (2 mL), NBS (250mg. 1.4 mmol) was dissolved with stirring at 0 C, and then the alkene (1 mmol) was added. The mixture was stirred for 1 h at 15 C, then poured into ice water and extracted with Et, 0. The Et O layer was washed with H O. aq NaHCOj, then H, 0 again, dried (Na2S04), and evaporated. 

C) Preparation of Triphenylmethyl Chloride (Sm.). Use the same apparatus and procedure as described in section (A). Place in the tube 10 ml of dry benzene and 3.2 g of dry carbon tetrachloride, and add as directed 2.4 g of aluminum chloride. When half of the chloride has been added, remove the ice water surrounding the reaction tube and add the remaining chloride in small portions. When all the chloride has been added, raise a small water bath over the reaction tube and heat for 30 minutes. Decompose the addition product by pouring it into a mixture of 10 g of ice and 10 ml of concentrated hydrochloric acid. Separate the benzene layer, and extract the aqueous layer with 5-6 ml of benzene. Dry... 

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