Hass-Bender reaction

The Hass or Hass-Bender Reaction will specifically convert a benzylic halide to an aldehyde ... 

This reaction was initially reported by Hass and Bender in 1949. It is the synthesis of aromatic aldehydes by treatment of substituted benzyl halides with sodium nitropropane salt (also called sodium propane-nitronate ). Therefore, this reaction is called the Hass-Bender reaction or Hass-Bender oxidation. This reaction also takes place on aromatic polycyclic compounds. ... 

Unsubstituted cycloamyloses have been used to catalyze a number of reactions in addition to acyl group transfer. Brass and Bender (8) showed that cycloamyloses promoted phenol release from diphenyl and bis(p-nitro-phenyl) carbonates and from diphenyl and bis(m-nitrophenyl)methyl phos-phonates. Breslow and Campbell (10,11) showed that the reaction of anisole with HOCL in aqueous solution is catalyzed by cyclohexaamylose and cycloheptaamylose. Anisole is bound by the cyclodextrins and is chlorinated exclusively in the para position while bound. Cycloheptaamylose has been used to promote regiospecific alkylation followed by the highly selective oxidation shown in reaction (3) (95). In addition cycloheptaamylose effec-... 

Metal-ion catalysis has been extensively reviewed (Martell, 1968 Bender, 1971). It appears that metal ions will not affect ester hydrolysis reactions unless there is a second co-ordination site in the molecule in addition to the carbonyl group. Hence, hydrolysis of the usual types of esters is not catadysed by metal ions, but hydrolysis of amino-acid esters is subject to catalysis, presumably by polarization of the carbonyl group (KroU, 1952). Cobalt (II), copper (II), and manganese (II) ions promote hydrolysis of glycine ethyl ester at pH 7-3-7-9 and 25°, conditions under which it is otherwise quite stable (Kroll, 1952). The rate constants have maximum values when the ratio of metal ion to ester concentration is unity. Consequently, the most active species is a 1 1 complex. The rate constant increases with the ability of the metal ion to complex with 2unines. The scheme of equation (30) was postulated. The rate of hydrolysis of glycine ethyl... 

F + Ha->FH + H.—Bender et al.26S recently reported the results of two different sets of calculations on the potential energy surface for the reaction F + H2-+ FH + H. This work is of interest from three points of view. First, it is truly a rigorous quantum mechanical calculation typifying the current state of the art for systems of this size a GTO basis set of double-zeta quality is used (9s5pj4s) for a total of 32 GTO s, and this is contracted according to the Dunning method51 to... 

C. A4 Molecules.—There are two cases of interest here stable species such as P4 and interactions between homonuclear diatomic molecules. H4 is the simplest of the species, and it has been the subject of a great deal of theoretical study because of its relevance to the H2 + D2 - -2HD exchange reaction. Early work has been carefully discussed by Schaefer,1 and Bender and Schaefer have carried out more extensive calculations since then on the linear form.604 It is predicted that two H2 molecules may approach to within 1.6 bohr with an energy only 181 kJ above that of the separated molecules. A van der Waals attraction of 22 K is predicted at a separation of the centre of mass of H2-H2 of 7.1 bohr. The results of other studies have failed to find a transition state lying less than 458 kJ above H2 + D2. The calculations of Bender et al. used a DZ basis plus 2p-functions, larger than that used in earlier work by Wilson and Goddard, and by Rubinstein and Shavitt (see ref. 1). Full Cl with 2172 configurations was carried out, and the van der Waals minimum predicted was not found by the earlier workers. 

Proton transfers are an integral part of acid and base catalysed reactions and as such they are important in chemical and biological processes (Jencks, 1969 Bender, 1971 Bell, 1973). DMSO has been found to influence many enzyme catalysed reactions, including hydrolytic processes, and its possible utility in enzymological studies has been noted (Rammler, 1971). 

The catalysis of hydrolysis of carboxylic acid derivatives by weak bases has not been carefully studied until relatively recently. Koshland reported in 1952 the catalysis of acetyl phosphate hydrolysis by pyridine Bafna and Gold (1953) reported the pyridine-catalyzed hydrolysis of acetic anhydride. A short time later the catalysis of aromatic ester hydrolysis by imidazole was demonstrated (Bender and Turnquest, 1957 a, b Bruice and Schmir, 1957). Since that time a large amount of work has been devoted to the understanding of catalyzed ester reactions. Much of the work in this area has been carried out with the purpose of inquiry into the mode of action of hydrolytic enzymes. These enzymes contain on their backbone weak potential catalytic bases or acids, such as imidazole in the form of histidine, carboxylate in the form of aspartate and glutamate, etc. As a result of the enormous effort put into the study of nucleophilic displacements at the carbonyl carbon, a fair understanding of these reactions has resulted. An excellent review is available for work up to 1960 (Bender, 1960). In addition, this subject has been... 

In this case acetylimidazole is spectrophotometrically observable as a transient intermediate (Bender and Tumquest, 1957a). The formation of acetylimidazole as an intermediate has been found to account exclusively for the hydrolysis reaction (Brouwer et ai., 1957). 

A two-step reaction sequence, and therefore a tetrahedral intermediate which lies on the reaction path, can be inferred from the pH-dependence of the hydrolysis rate of o-carboxyphthalimide (11) (Zemer and Bender, 1961). The hydrolysis of 11 is considerably more rapid than that of phthalimide at pH 1-5-4, but of similar rate at high and low pH values where hydroxide and hydrogen ion catalyses are important, as shown in Fig. 1. Furthermore, the extra reactivity of 11 has a maximum at pH ca. 2-9. Since the pA values of the two reagents are 3-65 (for 11), and 15-7 (for water), the rate maximum is not directly related to the acidity... 

The mechanism of the intramolecular general acid catalysis of the oxygen esters has not been established since the possible formation of anhydride intermediates has not been thoroughly investigated. The hydrolysis of phthalamic acid has been shown to proceed through an anhydride intermediate, detected by double labeling experiments (Bender et al., 1958a), as does the aminolysis of succinic acid. In these cases, the reaction may involve either a four-center path, symbolised by 40, or involve prior protonation followed by intermolecular attack by the carboxylate anion (41). 

---