Michael J. Chen

A Novel Fermentation Pathway in an Escherichia coli Mutant Producing Succinic Acid, Acetic Acid, and Ethanol

Escherichia coli strain NZN111, which is unable to grow fermentatively because of insertional inactivation of the genes encoding pyruvate: formate lyase and the fermentative lactate dehydrogenase, gave rise spontaneously to a chromosomal mutation that restored its ability to ferment glucose. The mutant strain, named AFP111, fermented glucose more slowly than did its wild-type ancestor, strain W1485, and generated a very different spectrum of products. AFP111 produced succinic acid, acetic acid, and ethanol in proportions of approx 2:1:1. Calculations of carbon and electron balances accounted fully for the observed products; 1 mol of glucose was converted to 1 mol of succinic acid and 0.5 mol each of acetic acid and ethanol. The data support the emergence in E.coli of a novel succinic acid:acetic acid:ethanol fermentation pathway.

Selective homologation of methanol catalyzed by transition metal complexes in methanol-amine solutions

Abstract Transition metal complexes of Mn, Rh, and Ru have been found to catalyze the homologation of methanol in methanol-amine solutions at syn-gas pressure near 300 atm and temperatures near 200°C. These catalysts are believed to operate by mechanisms similar to that proposed for Fe(CO)5, and likewise produce CO2 as the oxygenated by-product and do not homologate the ethanol product. The use of two metal complexes together as catalysts has also been examined. In a mixed Fe(CO)s-Mn2(CO)10 catalyst solution, methanol is converted at a rate of 14% h−1 at 200°C. Ethanol accounts for 72% of the product, the balance being methane. Additives such as phosphines and methyl iodide are found to affect the rate and the selectivity of these systems.

Oxygen atom transfer from μ-oxo-bis[1,4,8,11,15,18,22,25-octakis(trifluoromethyl)phthalocyaninato]diiron(III): evidence for an FeIV=O intermediate †

The dimeric [(FPc)Fe]2({mu}-O) (1) (FPc is the dianion of 1,4,8,11,15,18,22,25-octakis(trifluoromethyl)phthalocyanine) has been shown to transfer its -oxo atom quantitatively to trimethylphosphine and triphenylphosphine. In the case of triphenylphosphine a base such as 1-methylimidazole (MeIm) or pyridine (py) is needed to induce the oxygen atom transfer. The reaction of 1 with MeIm at -40 C and below gives [(MeIm)(FPc)Fe]2({mu}-O) (4), which disproportionates to give (MeIm)2(FPc)Fe (5) and (FPc)Fe=O (6) at higher temperatures. The oxo atom of 6 has been shown to transfer to triphenylphosphine. Similarly, 6 is generated by the disproportionation of 1 with py. It has also been generated by the oxidation of 1 with t-butyl hydroperoxide. [(FPc)Fe]2({mu}-O) catalyzes the oxidation of hydrocarbons by iodosylbenzene. With stilbenes, styrenes, cyclohexenes and butenes as substrates, both epoxidations and alkyl C-H bond oxidations have been observed. The epoxidation of cis-stilbene leads to a mixture of cis- and trans-stilbene oxides, indicating that epoxidation of cis-stilbene, and possibly other olefins as well, proceeds through a non-concerted mechanism.

Unusual tautomerism involving proton migration between metal and pyrrolic nitrogen in a hydridorhodium phthalocyanine complex

Hydrido(1,4,8,11,15,18,22,25-octapentylphthalocyanato)rhodium, an unprecedented hydrido metallophthalocyanine, exhibits an unusual tautomerism involving proton migration from rhodium to pyrrolic nitrogen.