Ueber die Synthese der Oxalinbasen

SummaryIn aqueous acetonitrile (AN), Cu (I) forms the complexes Cu (AN)L+ and CuL: with a series of substituted imidazoles (L). Stability constants logK of Cu(AN)++L+Cu(AN)L+ and logp, were near 5 and 12, resp., log units for all ligands. The rate of autoxidation is described by, implying competition between one-or two-electron reduction of 02. The value of k, decreases from ~~O O M -~S -~ for unsubstituted imidazole to about 40 ~~~8 -l for 2-methylimidazole or 1,2-dimethylimidazole and essentially zero for the corresponding 2-ethyl-derivatives. On the other hand, k , and kb are much less influenced by the nature of the ligands, all values being near 5 . 104~-2s-1 and 103~-',respectively, for the complexes with the last four bases. Thus rather subtle sterical changes may strongly influence the relative importance of different pathways in the reduction of dioxygen by cuprous complexes.In a previous paper [ 11 we have presented kinetic evidence for simultaneous oneand two-electron reduction paths in the autoxidation of Cu (1-methyl-2-hydroxymethylimidazole): (MEOHIM). In order to obtain information on the factors governing the relative importance of either mode of 0, reduction, we have studied the autoxidation of the Cu (I) complexes with 2-methylimidazole (MEIM), 1,2-dimethylimidazole (DIMEIM), 2-ethylimidazole (ETIM), 1-methyl-2-ethylimidazole (MEETIM), 1,2,4-trimethylimidazole (TRIMEIM), and 1,2,4,5-tetramethylimidazole (TEMEIM). With the choice of this series of ligands (L) we could concentrate mainly on sterical factors while keeping electronic influences relatively small. Included in this comparative study are some earlier results with unsubstituted imidazole ( Part VII, see [ 11.

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“…82-85", lit. : 79-80" [9], from light petroleum); and TEMEIM (BASF, Ludwigshafen2), m.p. 51-54", lit.…”

mentioning

confidence: 99%

Cuprous complexes and dioxygen. VIII. Steric factors controlling one‐ or two‐electron reduction of O₂ by cuprous complexes with substituted imidazoles

Güntensperger

Zuberbühler

1977

Helvetica Chimica Acta

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“…5-(Imidazol-2-yl)uracil (6). A 25-ml three-neck flask containing 1.4 g (10 mmol) of 5-formyluracil (5) and a stirring bar was fitted with two dry ice condensers and a rubber septum and cooled in a dry ice bath.…”

Section: -Formyluracil (5) This Synthesis Was Adapted Frommentioning

confidence: 99%

“…Difficulties were encountered in the preparation of the f Dedicated to Edward E. Smissman, Chairman of this Department from 1960 until his death on July 14, 1974. 5-(imidazol-2-yl)uracil (6). The initial attempt, a classical imidazole synthesis,6 was by treatment of 5 with aqueous ammonia and glyoxal; the desired product could not be obtained.…”

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confidence: 99%

Synthesis of 5-substituted uracil derivatives

Ressner¹,

Fraher²,

Edelman³

et al. 1976

J. Med. Chem.

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The synthesis of a series of 5-substituted uracil derivatives is described. 5-Bromoacetyluracil (2a) was converted to the glycolyl (2b), glycyl (2c), N,N-dimethylglycyl (2d), 4-imidazolyl (3), and 2-amino-4-thiazolyl (4) derivatives. 5-Formyluracil (5) was used in the preparation of the 2-imidazolyl (6), the 3-acrylic acid (7b), the ester (7a), and the 3-N,N-dimethylacrylamide (8) derivatives. A Mannich reaction converted 5-acetyluracil to the amino ketone 9 which was reduced to give the 3-dimethylamino-1-propanol derivative 10. Compounds 2b,d,3,4,6, and 7b failed to inhibit the growth of Escherichia coli B and Staphylococcus aureus.

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“…Many researchers working with ionic liquids (ILs) are likely familiar with the postulate that there are at least 1 million (10 6 ) readily accessible ILs that can be synthesized using commercially available starting materials. , Although the explicit methodology from which we arrive at 10 6 ILs has not been fully detailed in the literature, this assertion is easily supported by a rudimentary analysis of the requisite starting materials and moieties that comprise an IL. Consider the following thought process through which we arrive at a large number of unique 1,3-difunctionalized imidazolium-based ILs (Figure ); N -functionalized imidazoles can be synthesized from imidazole and an alkyl halide (or similar X-C y H z molecule), the Radziszewski reaction, − or other methods. − We selected 50 different imidazoles that have appeared in the literature, each with a different, relatively simple hydrocarbon substituent. Of course, there are many more known imidazole compounds, but we will use 50 for the purposes of this exercise.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Frequency and Diversity of 1,3-Dialkylimidazolium Ionic Liquids Appearing in the Literature

Scalfani

Alshaikh

Bara

2018

Ind. Eng. Chem. Res.

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The hypothetical assertion that there are potentially millions of ionic liquids (ILs) can be validated using basic knowledge of IL precursors and simple calculations. While it is an interesting thought exercise to ponder the possibilities of ILs, it is important to investigate how many discrete ILs (i.e., unique cation and anion pairings) have actually been synthesized and reported in the literature. A complete analysis of all ILs is a daunting task, especially if the definition of what constitutes an IL is broad. Nonetheless, insight can be gained into the use of ILs over the past ∼20 years from a focused analysis of systematically varied 1,3dialkylimidazolium-based ILs (i.e., [R 1 R 2 im][X], where R 1 and R 2 are n-alkyl chains and X is either a halide or molecular anion). This family of ILs includes many of the most widely used and most thoroughly studied IL substances, including 1-butyl-3-methylimidazolium hexafluorophosphate ([C 4 mim][PF 6 ]) and 1-ethyl-3-methylimidazolium bistriflimide ([C 2 mim][Tf 2 N]). Using data retrieved from SciFinder searches, we analyzed the variety and frequency of 1,3-dialkylimidazolium-based ILs appearing in the literature. Our analysis reveals that there is a relatively large number of simple 1,3-dialkylimidazolium cations which have not yet been synthesized. Our findings indicate that despite the broad possibilities of IL structures available, there are but a handful of ILs that are commonly used and studied. Within the 1248 [R 1 R 2 im][X] ILs studied, there were only 12 cations extensively used, which included [R 1 R 2 im] + (R 1 = C 1 and R 2 = C 1 −C 12 ). Of the 16 anions studied, only 5, including [BF 4 ] − , [Cl] − , [PF 6 ] − , [Tf 2 N] − , and [Br] − , were used significantly. Thus, it appears that although ILs can be used as designer solvents with task-specific properties, there is a small default subset of ILs, which are "go-to" or "one-size-fits-all." We rationalize the current state of the IL landscape in terms of the historical perceptions (and misconceptions) around ILs, familiarity, availability and cost of starting materials, commercial availability of ILs, and the motivations from which researchers choose to synthesize and characterize new ILs.

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Ueber die Synthese der Oxalinbasen

Cited by 17 publications

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Cuprous complexes and dioxygen. VIII. Steric factors controlling one‐ or two‐electron reduction of O₂ by cuprous complexes with substituted imidazoles

Cuprous complexes and dioxygen. VIII. Steric factors controlling one‐ or two‐electron reduction of O₂ by cuprous complexes with substituted imidazoles

Synthesis of 5-substituted uracil derivatives

Analysis of the Frequency and Diversity of 1,3-Dialkylimidazolium Ionic Liquids Appearing in the Literature

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Ueber die Synthese der Oxalinbasen

Cited by 17 publications

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Cuprous complexes and dioxygen. VIII. Steric factors controlling one‐ or two‐electron reduction of O2 by cuprous complexes with substituted imidazoles

Cuprous complexes and dioxygen. VIII. Steric factors controlling one‐ or two‐electron reduction of O2 by cuprous complexes with substituted imidazoles

Synthesis of 5-substituted uracil derivatives

Analysis of the Frequency and Diversity of 1,3-Dialkylimidazolium Ionic Liquids Appearing in the Literature

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Product

Resources

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Cuprous complexes and dioxygen. VIII. Steric factors controlling one‐ or two‐electron reduction of O₂ by cuprous complexes with substituted imidazoles

Cuprous complexes and dioxygen. VIII. Steric factors controlling one‐ or two‐electron reduction of O₂ by cuprous complexes with substituted imidazoles