Benzil, Table

Rate constants and Arrhenius parameters for the reaction of Et3Si radicals with various carbonyl compounds are available. Some data are collected in Table 5.2 [49]. The ease of addition of EtsSi radicals was found to decrease in the order 1,4-benzoquinone > cyclic diaryl ketones, benzaldehyde, benzil, perfluoro propionic anhydride > benzophenone alkyl aryl ketone, alkyl aldehyde > oxalate > benzoate, trifluoroacetate, anhydride > cyclic dialkyl ketone > acyclic dialkyl ketone > formate > acetate [49,50]. This order of reactivity was rationalized in terms of bond energy differences, stabilization of the radical formed, polar effects, and steric factors. Thus, a phenyl or acyl group adjacent to the carbonyl will stabilize the radical adduct whereas a perfluoroalkyl or acyloxy group next to the carbonyl moiety will enhance the contribution given by the canonical structure with a charge separation to the transition state (Equation 5.24). 

A quick perusal of Table 3 shows inverted stability for a and /3 isomers of phenyl-glyoxime and p-tolylglyoxime. Given uncertainties as to stereochemistry it is plausible that the structural assignments of Z and E, syn and anti, even a and /3 were reversed. This is understandable. However, it is inexplicable that the tolyl species have enthalpies of formation at least 150 kJ moH more positive than the phenyl compounds. This is an altogether implausible result. The solid phase reaction 35 is calculated to be ca 75 kJmol exothermic if we use the averaged value for the various stereoisomers of phenylglyoxime and benzil dioxime. This, too, is implausible. 

Table I. Influence of Solvent and Temperature on the Calibration Constant with Benzil as Calibrating Compound...

In the reduction of an optically active ketone, the reaction results in the creation of an additional asymmetric center, and two diastereoiso-mers are possible. In many cases it has been found that both isomers are formed, often in comparable amounts. For example, reduction of camphor (XY) gives a mixture of bomeol and isobomeol (XVI).6 Numerous other examples may be noted in the tables at the end of this chapter. However, the reduction of benzil (XVII) or benzoin (XVIII) is reported to give 90% of wieso-hydrobenzoin (XIX). 6... 

TABLE 10.4. Lethal doses of 3-Quinuclidinyl benzilate and other anticholinergic drugs for different species... 

A third compilation intended to be devoted to polymorphic materials is that of Kuhnert-Brandstatter (1971). The body of this book is an identification table for hot stage studies of pharmaceutical materials (see Sections 4.2 and 7.2), in which materials are arranged by increasing melting point, with eutectic data for mixtures with azobenzene and benzil. There is considerable descriptive detail on the melting behaviour and identification and description of polymorphic forms, albeit only microscopic determinations, for approximately 1000 pharmaceutically important... 

The reaction between aromatic 1,2-diamines and 1,2-diketones affords 2,3-disubstituted quinoxaline derivatives (see table below) " however, a number of hindered a-ketones fail to react. " Unsymmetrical diketones give mixtures of isomers whose ratio varies with the acidity of the medium in some examples. A mechanistic study of quinoxaline formation from benzene-1,2-diamine and benzil has been described." ... 

Table 11. Rate constants for decarboxylation of MV -benzilate and arylacetate ion pairs...

Before proceeding with a discussion of the effects of 3-qulnuclidlnyl benzilate, it may be worth while to look at the available information on the lethality of single doses of the benzlllc acid esters with which we are concerned. Table 1-2 is based on information supplied by Hoffman-LaRoche, Inc., the Sterllng-Wlnthrop Research Institute, and a number of investigators (36,173,176,178-189). 

Considering the formation of C02" on CdS-DMF, we successfully applied the CdS-DMF photocatalysis to the fixation of CO2 into benzophenone (BP), acetophenone (AP), and benzyl halides (BnCl and BtiBr) (Table 1). Four substrates gave benzilic acid, atrolactic acid, and phenylacetic acid as respective fixation products, with dimerized and hydrogenated products. Considering the mechanism proposed above, C02 formed through the same route as described therein should participate in the fixation reaction. 

The generality of the rearrangement is further illustrated by the reaction of 2,2 -furil with hydroxide ion in dry ether (Table 1). Likewise, 2,2 -pyridil is rearranged in hot methanol solution (40 min) to give the sodium salt of 2,2 -pyridilic acid (86%). Acidification, however, affords bis(2-pyridyl)methanol by decarboxylation since 2,2 -pyridilic acid (16) is structurally similar to a -keto acid. Benzilic rearrangement of 2,2 -pyridil with methanolic nickel(ll) and cobalt(II) acetates results in the formation of metal complexes of 2,2 -pyridilic acid (17 92%). A plausible mechanism is summarized in Scheme 4. Rearrangement is also observed with 2,2 -quinaldil, but benzil, 2,2 -furil or 1-phenyl-2-(2 -pyridyl)ethane-1,2-dione are not susceptible to these metal template reactions. 

Benzilic acid rearrangement is usually carried out by heating benzil derivatives and an alkali metal hydroxide in aqueous organic solvent. This reaction also proceeds efficiently in the solid state. For example, a mixture of finely powdered benzil (35a) (0.5 g, 2.38 mmol) and KOH (0.26 g, 4.76 mmol) was heated at 80 °C for 0.2 h, and the reaction mixture was mixed with 3N HCl (20 ml) to give benzilic acid (39a) as colorless needles (0.49 g, 90% yield) [13]. Since the product is collected simply by filtration, this method is very simple and economical. Similar treatment of benzil derivatives (35b-g) in the solid state also gave the corresponding benzilic acid (39b-g) in good yields (Table 15-8) [13],... 

Table 15-8. Yields of benzilic acid 39 produced by treatment of benzil bolo 35 with KOH at 80 C in the solid state.

Table 3.8 Basicity and Anticholinergic Activity of Substituted Aminoethyl Esters of Benzilic Acid...

As shown in Fig. 2 and Table 1, xanomeline displayed higher affinity than CDD-0102 in binding to M, and M, muscarinic acetylcholine receptors, as measured by the inhibition of pH](/ )-quinuclidinyl benzilate (QNB) binding. Both compounds exhibited higher affinity for Mj receptors than for M, receptors, a common finding with muscarinic agonists. This may reflect inherent differences between receptors coupled to the G and G families of G proteins. 

Important results of these experiments are reported in Table 3.10 for polymer/polymer reactions and reactions between polymers and small molecules in dilute solution.3 1 The solvent dependence of the polymer/polymer reaction is attributed to the viscosity t/0 of the solvent and to coil expansion (excluded volume effect). By multiplying kq by the ratio the effects of solvent viscosity and reaction temperature can be eliminated from the data and the effect of coil expansion on the reactions can be compared. In the case of a reaction between a small molecule and one polymeric chain end (e.g. benzil, B, and PS-A with AMO2),... 

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