Biltz reaction

The rate of coagulation of night blue examined by Biltz and Steiner Zeit, Phys. Ohem, LXXili. 607, 1910) and of benzo-purpurin (Biltz and v, Vegesack, Zeit. Phys. Ghem. lxxiii. 500, 1910) likewise appear to conform reasonably closely to a reaction of the autocatalytic variety. 

Biltz et al method (Ref 2) in which alloxan monohydrate is heated (80—90°) with anhydr urea followed by bubbling dry HC1 gas thru the mixt. The reaction is then drowned in w, cooled, filtered and recrystd from boiling w. Yield is 61.9% of theory. Spirodihydantoin is the parent compd of Dinitrospirodihydantoin (see below)... 

AS2 (g). The vapor density data of Mitscherlich,1 Bineau,1 Deville and Troost,2 Mensching and Meyer,1 Biltz and Meyer,1 and Preuner and Brockmoller1 yield for the reaction, As (g)=2As2(g), Q1000=—25.0, or about —21 at 18°. 

Fe203 (c). For the heat of combustion of Fe203 (c) to form Fe304 (c), LeChatelier,8-10 found —15 and Roth5 —20.6. The latter value yields, for Fe203 (c), Qf=198.5. Mixter s15 data on the reaction with sodium peroxide yield 194.6. Berthelot70 measured the heat of solution of iron in HC1(4) to be 17.1. See also Walden,1 Biltz,8 Sosman and Hostetter,1 and Treadwell.1... 

Biltz prepared phenytoin by heating urea with a previously prepared alkaline alcoholic solution of benzil. Sikdar and Ghosh studied the mechanism of the Biltz technique and has shown the reaction to take place as shown in Scheme 2. 

Thus Jones, W. Biltz,f and others have attempted to calculate the number of water molecules combined with the solute in aqueous solutions by assuming that x =, or, in other words, that the hydration of the solute is complete. These calculations lead, however, to somewhat improbable values for the number of combined water molecules n. On the other hand, assuming n =, Dolezalek has calculated the values of x for mixtures of organic liquids from the vapour pressure measurements of Zawidzki, and has succeeded in showing that the law of mass action holds for solvation as it does for other reactions. J... 

Biltz and Mumin state that this compound is really a trichloro-mcrcuri-aeetaldehyde, C(HgCl)3.CHO, The evidence put forward is that the analysis corresponds to this formula, and also that the following equation may represent the reaction ... 

A direct measurement of the enthalpy of formation has not been made. An estimate of A H is obtained by a method suggested by Parker (1 ). Biltz and Uesserknecht (2) have measured the enthalpies of solution of BeCl Ccr) and BeBr Ccr) in aqueous HCl (18.69%). Samples (3) of the dihalides were prepared from reactions of BeO-C mixtures with the halogens at elevated temperatures. We assume that the two dihalides had similar structures, i.e. o form. A.H (BeBr., in 18.7% HCl, 298.15... 

These results drew attention to a reaction studied by Biltz and Kramer in 1924, the general applicability of which, however, was not recognized for 50 years These authors studied the reaction of ethyl diazoacetate with the tetrahydrate of pyrimidine-2,4,5,6-tetrone (9.11, alloxane) and found the addition product 9.12 (9-10). 

Condensation of urea with carbonyl compounds A rapid and efficient MW-assisted synthesis of hydantoins and thiohydantoins was described by Muccioli et al. [117]. The most straightforward conditions for synthesis of phenytoin are the base-catalyzed condensation using benzil and urea, known as the Biltz synthesis (Eq. 33). MW activation of the Biltz synthesis of phenytoin improved both yield and reaction time. The first step consists in MW activation of the reaction of benzil with (thio)urea the second includes the conversion of the resulting 2-(thio)hydantoin to hydantoin using hydrogen peroxide. When reactions were performed at the same temperature under both reaction conditions, yields were by far better under the action of MW and emphasized the evident specific MW effects. These are perfectly expected when one considers the polar TS involved in the first step (nucleophilic addition of neutral NH2 group on carbonyl moiety). 

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