Thiele reagent

CrOi-acetic anhydride-H Ot (Thiele reagent). This powerful reagent converts an arylmethyl compound into the diaeetate of an aldehyde, from which the aldehyde can be recovered by acid hydrolysis ... 

Prediction.s of the benefits then show up in Figs. 28 and 29. Without any convection (zero imposed pressure difference), at a Thiele modulus of 5, the concentration profile inside the network is as shown in Fig. 28. There is a severe depletion of primary reagent into the network, and only the ends see sufficient reagent. With imposed convection (at a X value of 750) for the same Thiele modulus, the effectiveness factor ratio becomes 2.84. The impact of the imposed convection is shown in Fig. 29. The flow generated within the network is quite nonuniform, as the fingers of high concentration show. This... 

In this group, too, the first observations were made by Thiele 192), who found that cuprous and silver ions are precipitated from aqueous ammoniacal solution by cyclopentadiene, but gave no analytical data. Thallium was later found to be precipitated similarly. Copper (I), however, also yields a white crystalline cyclopentadienyl-triethylphosphine complex, C5H5CuP(C2H5)3, which is stable to water 215) this was, in fact, analogous to an earlier method described by van Peski and Melsen. Attempts to make a complex by the Grignard reagent method or by the action of cyclopentadienyl sodium on cuprous halides were unsuccessful. 

The reagent can be used also for the Thiele reaction, that is, acid-catalyzed addition of acetic anhydride to a quinone with further conversion into the hydroquinone... 

Constant diffusivity (D ) and the solid-liquid mass-transfer coefficient are assumed for QX and QY. The model equations are nondimensionalized in terms of the Thiele parameter (f>, Biot number for mass transfer Bi, and nondi-mensional time and distance. An important conclusion from the subsequent analysis of the model simulations is the importance of the solid phase on the conversion of the organic substrate in the organic phase. Results of their simulation are shown in Figure 11. It can be noticed that at low (f>, corresponding to low diffusional limitations, the overall organic reagent conversion is lower than at higher values o <. This result is the exact opposite of what is observed in analysis of... 

The synthetic scope of the Thiele-Winter reaction of quinines with acetic anhydride can be increased by the use of triflic acid (eq 46). Reaction of cyclopropylacylsilanes with triflic acid in aprotic solvent affords the corresponding cyclobutanone or 2-silyl-4,5-dihydrofuran derivatives. Triflic acid can react with >-iodosylbenzoic acid to form a hypervalent iodine reagent, which reacts with 1-trimethylsilylalkynes to afford alkynyliodonium tri-flates bearing a carboxy group in high yields (eq 47). Reaction of (diacetoxyiodo)benzene [PhI(OAc)2] with excess triflic acid results in oligomerization of PhI(OAc)2- ... 

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