P-Anisaldehyde stain

The rate of reaction is highly variable depending on the UV source. The reaction is easily monitored by TLC on silica gel using ethyl acetate-hexane (1 1) as the eluent and p-anisaldehyde stain. The Rf values and staining colors ot starting materials and products follow 9-ethyl-3,6-dimethylcarbazole R = 0.95 (gray) 3, 5 -di-0-benzoyl-2 -0-((3-trifluoromethyl)benzoyl]-5-methyluridine R = 0.75 (pink-purple) 5 -0-benzoyl-3 -deoxythymidine Rf = 0.55 (aqua blue) 3 ,5 -di-0-benzoylthymidine Rf = 0.30 (brown-black). 

Thin layer chromatographic (TLC) analysis was performed on Baker Si250F precoated plates with ethyl ether as the solvent. The approximate Rf values for the monoacetate and diacetate under these conditions are 0.44 and 0.72, respectively. The compounds were visualized using p-anisaldehyde stain. 

Most of the reactions described in the following chapters were monitored by Thin Layer Chromatography (TLC) using plastic TLC plates coated with a thin layer of Merck 60 F254 silica gel. The products were detected by using an ultraviolet lamp or the TLC plates were treated with p-anisaldehyde reagent, prepared as explained below, and then heated to 120 °C to stain the spots. After visualization and measurement, the Rf values were recorded. 

The reaction was monitored by TLC (eluent -hcxanc diethyl ether, 9 1). ( )-Stilbene was UV active, Rf 0.82. The epoxide (UV active) stained blue with p-anisaldehyde, Rf 0.70. 

The reaction was followed by TLC (eluent petroleum ether-ethyl acetate 75 25). The acetophenone was UV active, stained yellow with p-anisalde-hyde, Rf 0.68. Phenylethanol had a low UV activity, stained purple with p-anisaldehyde, R 0.46. 

The a-acetoxy ether elutes with an Rj of 0.32 on Merck silica gel in 5% (v/v) ethyl ether in hexanes (product stains yellow-green in an acidic solution of p-anisaldehyde). 

Novozym 435 lipase (2.0 g, Sigma-Aldrich) was added to a suspension of meso diacetate (15.0 g, 81.5 mmol) in phosphate buffer (pH 8,400 mL, 1 M). (Note Hydrolysis liberates acetic acid. The high concentration of buffer maintains the pH near 8.) The mixture was stirred at room temperature and monitored by thin layer chromatography (silica gel eluted with ethyl ether, stained with p-anisaldehyde kf (monoacetate) = 0.44, f (diacetate) = 0.72). After 18h, the diacetate was completely converted to monoacetate, so the reaction was filtered to... 

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