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R.A. Friedel

Bio: R.A. Friedel is an academic researcher from United States Bureau of Mines. The author has contributed to research in topics: Coal & Chemical reaction. The author has an hindex of 11, co-authored 33 publications receiving 571 citations.

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TL;DR: Benkeser et al. as mentioned in this paper showed that the lithium-ethylenediamine system is a convenient and effective metal-amine combination for carrying out reductioiis and cleavage reactions of organic compound.
Abstract: The present invest,igat'ion deals with the reduction of organic compounds by the lit,hium-ethylenediamine system. Most st'udies with metal-ammonia and metal-amine syst'ems have been carried out using liquid ammonia. Although Kraus2 predicted in 1953 that methylamine, ethylamine, and ethylenediamine would be valuable solvents for studying the physico-chemical properties of solutions of metals in amines at higher temperatures, ethylenediamine has not hitherto been used in a metal-amine reducing system. The first use of the lower aliphatic amines for metal-amine reductions was recently reported by Benkeser et u Z . , ~ who showed that aromatic rings are reduced to monoolefins by lithiumethylamine. However, their attempt to replace ethylamine by higher primary amines gave poor yields, perhaps because lithium becomes progressively less soluble in these monofunctional amines as t'he ratio of nitrogen to carbon decreases. Since ethylenediamine contains one amine group per carbon at,om, and since its relatively high boiling point (117") is a potential advantage, we decided t'o investigate its use in a metal-amine system. Our results show that the lithium-ethylenediamine system, a t 90-loo", is a convenient and effective metal-amine combination for carrying out' reductioiis and cleavage react'ions of organic compound^.^

56 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the preparation of alkyl and aryl π-cyclopentadienyl carbon monoxide or nitric oxide compounds of Cr, Mo, W, and Fe is described.

652 citations

Journal ArticleDOI
TL;DR: In this article, the sequence of condensation of mineral phases from a cooling nebula of solar composition has been calculated by using equilibrium thermodynamics, and theoretical models suggest that the chemistry and mineralogy of Ca-Al-rich inclusions in C2 and C3 chondrites were established during condensation at temperatures above 1300 K.
Abstract: By using equilibrium thermodynamics, the sequence of condensation of mineral phases from a cooling nebula of solar composition has been calculated. The theoretical models suggest that the chemistry and mineralogy of Ca-Al-rich inclusions in C2 and C3 chondrites were established during condensation at temperatures above 1300 K. Fractionation of such inclusions is necessary to account for the refractory element depletions of ordinary and enstatite chondrites relative to the carbonaceous chondrites. The metal-silicate fractionation in ordinary chondrites took place in the nebula at a temperature below 1000 K and at .00001 atm total pressure. The volatile element depletion of C2 and C3 chondrites relative to C1 chondrites took place during chondrule formation: the most volatile elements are depleted in ordinary chondrites because they accreted before these elements were totally condensed.

580 citations

Journal ArticleDOI
TL;DR: The present review offers an overview of nonclassical (e.g., with no pre- or in situ activation of a carboxylic acid partner) approaches for the construction of amide bonds.
Abstract: The present review offers an overview of nonclassical (e.g., with no pre- or in situ activation of a carboxylic acid partner) approaches for the construction of amide bonds. The review aims to comprehensively discuss relevant work, which was mainly done in the field in the last 20 years. Organization of the data follows a subdivision according to substrate classes: catalytic direct formation of amides from carboxylic and amines (section 2); the use of carboxylic acid surrogates (section 3); and the use of amine surrogates (section 4). The ligation strategies (NCL, Staudinger, KAHA, KATs, etc.) that could involve both carboxylic acid and amine surrogates are treated separately in section 5.

556 citations

Journal ArticleDOI
TL;DR: The use of the element as an indicator in geochemical prospecting for various types of mineral deposits is outlined in this paper, where the geochemistry of arsenic is reviewed, and the use of arsenic as a significant component of many types of gold and silver deposits is discussed.

378 citations