Bartlett studies

L. Carius,8 A. Scott, R. J. Friswell, W. Luzi, and others have studied the action of nitric acid on carbon and graphite—vide 5. 39,11. L. R. Parks and P. C. Bartlett studied the adsorption of nitric acid by charcoal and N. Sehiloff and S. Pewsner the adsorption force between charcoal and nitric acid. M. J. M. Creighton and... 

Bartlett studied the photolysis of the azo compound 20 with ESR spectroscopy 35>. A triplet ESR signal could be detected at low temperature, which is thought to be due to a triplet radical pair 20. This radical pair is thought to be held apart by a nitrogen molecule at about 7 A. Warming up the system produces the ESR signal of the monoradical. This result is however in contradiction with recent CIDNP studies (see below). 

For example, Conant and Bartlett studied the formation of semicarbazones from a solution composed initially of equal concentrations of cyclohexanone (65), furfural (66), and semicarbazide hydrochloride (67) in a solution of KOAc in 50% aqueous ethanol. The product isolated after a reaction period of 20 seconds was cyclohexanone semicarbazone (68, equation 6.57). However, when the reaction was allowed to proceed for 2.5 hours, the product was furfural semicarbazone (69, equation 6.58). ... 

Nonclassical ions, a term first used by John Roberts (an outstanding Caltech chemist and pioneer in the field), were defined by Paul Bartlett of Harvard as containing too few electrons to allow a pair for each bond i.e., they must contain delocalized (T-electrons. This is where the question stood in the early 1960s. The structure of the intermediate 2-norbornyl ion could only be suggested indirectly from rate (kinetic) data and observation of stereochemistry no direct observation or structural study was possible at the time. 

In a definitive study of butadiene s reaction with l,l-dichloro-2,2-difluoio-ethylene, Bartlett concluded that [2+4] adducts of acyclic dienes with fluorinated ethylenes are formed through a mixture of concerted and nonconcerted, diradical pathways [67] The degree of observed [2+4] cycloaddition of fluorinated ethylenes IS related to the relative amounts of transoid and cisoid conformers of the diene, with very considerable (i.e., 30%) Diels-Alder adduct being observed in competition with [2+2] reaction, for example, in the reaction of 1,1 -dichloro-2,2-difluoro-ethylene with cyclopentadiene [9, 68]... 

In the course of a study into the structure of ibogamine and related compounds Bartlett d found that if the keto acid 129 was heated... 

Mechanistic understanding of azo coupling reactions was initiated by Conant and Peterson (1930) and Wistar and Bartlett (1941) in two pioneering studies done at Harvard University (see Sec. 12.7). 

For pioneering studies on these constants see Bartlett (1934, pKa) and Schwarzenbach and Witt-wer (1947, for KE). 

Watmough, N.J.. Turnbull, D.M., Sherratt. H.S.A. Bartlett. K. (1989). Measurement of the acyl-CoA intermediates of p-oxidation by hplc with on-line radiochemical and photodiode-array detection. Application to the study of [U- C]hexadecanoate by intact rat liver mitochondria. Biochem. J. 262,261-269. 

Cycloaddition of bicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic anhydride 81 with cyclopentadiene was also studied by Bartlett et al., who found exclusive top addition, the top-endo/top-exo ratio being 3 2 [147]. The endolexo ratio is significantly different from that of 80 (60-70 1). The observed top selectivity in norbornadiene (80) and norbomene (81) derivatives is consistent with the inherent top reactivity of norbomanone 25 and norbomene 57. Orbital unsymmetrization of the dienophile... 

Since the discovery of the first noble gas compound, Xe PtF (Bartlett, 1962), a number of compounds of krypton, xenon, and radon have been prepared. Xenon has been shown to have a very rich chemistry, encompassing simple fluorides, XeF2> XeF, and XeF oxides, XeO and XeO oxyf luorides, XeOF2> XeOF, and Xe02 2 perxenates perchlorates fluorosulfates and many adducts with Lewis acids and bases (Bartlett and Sladky, 1973). Krypton compounds are less stable than xenon compounds, hence only about a dozen have been prepared KrF and derivatives of KrF2> such as KrF+SbF, KrF+VF, and KrF+Ta2F11. The chemistry of radon has been studied by radioactive tracer methods, since there are no stable isotopes of this element, and it has been deduced that radon also forms a difluoride and several complex salts. In this paper, some of the methods of preparation and properties of radon compounds are described. For further information concerning the chemistry, the reader is referred to a recent review (Stein, 1983). 

Bartlett JG, Condon RE, Gorbach SL, Clarke JS, Nichols RL, Ochi S Veterans Administration Cooperative Study on Bowel Preparation for Elective Colorectal Operations Impact of oral antibiotic regimen on colonic flora, wound irrigation cultures and bacteriology of septic complications. Ann Surg 1978,188 249-254. 

Clarke JS, Condon RE, Bartlett JG, Gorbach SL, Nichols RL, Ochi S Preoperative oral antibiotics reduce septic complications of colon operations Results of a prospective, randomized, double-blind clinical study. Ann Surg 1977 186 251-259. 

The equilibrium between 1,1-dimethylethylperoxyl radicals and 1,1-dimethylethyl tetroxide was first evidenced by Bartlett and Guaraldi [157] for peroxyl radicals generated by irradiation of bis( 1,1-dimethylethyl) peroxycarbonate in CH2C12 at 77 K and oxidation of 1,1-dimethylethyl hydroperoxide with lead tetraacetate at 183 K in CH2C12. A series of studies of this equilibrium were performed later using the EPR technique (see Table 2.12). It is seen that the enthalpy of tetroxide decomposition ranges from 29 to 47 kJ mol-1. 

Such decay is known as concerted fragmentation. Peroxides have the weak O—O bond and usually decompose with dissociation of this bond. The rate constants of such decomposition of ROOR into RO radicals demonstrate a low sensitivity of the BDE of the O—O bond to the structure of the R fragment [4], Bartlett and Hiat [8] studied the decay of many peresters and found that the rate constants of their decomposition covered a range over 105 s-1. The following mechanism of decomposition was proposed in parallel with a simple dissociation of one O—O bond [3,4] ... 

These substitution reactions were discovered by Nozaki and Bartlett [57,58] in their study of benzoyl peroxide decomposition in different solvents. When benzoyl peroxide is decomposed, the formed benzoyloxyl radical attacks the solvent (RH), and the formed alkyl radical (R ) induces the chain decomposition of the peroxide (see Chapter 3). 

Presumably, in these systems the energy cost of ring puckering is greater than the stabilization due to bishomoaromaticity (Bartlett and Rice, 1963). However, if the ring is already forced into a puckered conformation (e.g. by bridging between the 3 and 5 positions) then homoaromatic stabilization becomes effective. Solvolytic studies on the bridged systems [30] and [31]... 

In general, it is considered very unlikely that free radicals exist as non-classical structures (Walton, 1987). Kinetic and product studies involving the 2-norbornyl radical revealed the lack of importance of the non-classical species (Bartlett and Pincock, 1962 Martin and De Jongh, 1962 Bartlett and McBride, 1965). More recent ESR studies on the systems [150] and [151], in which the geometry was considered favourable for homoconjugation, again demonstrated the ineffectiveness of non-classical structures for radicals (Walton, 1987). 

Bartlett PA, Bauer B, Singer S (1978) Synthesis of water-soluble undecagold cluster compounds of potential importance in electron microscopic and other studies of biological systems. J Am Chem Soc 100 5085-5089... 

For more than forty years the Bartlett butterfly TS was the generally accepted mechanism for peracid epoxidation and numerous experimental studies supported this transition structure" " . During these formative years theoretical calculations did not play a major role due to limitations of available methods that could adequately treat the peroxide functional group. Theoretical contributions in 1978 were at the Hartree-Fock (HF) level since... 

R.B. Hirschl, M. Croce, D. Gore, H. Wiedemann, K. Davis, R.H. Bartlett, Prospective, randomized, controlled pilot study of partial liquid ventilation in adult acute respiratory distress syndrome. Am. J. Respir. Crit. Care Med. 165 (2002) 781-787. 

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