Donald james cram april 22, 1919 june 17, 2001 was an american chemist who shared the 1987 nobel prize in chemistry with jeanmarie lehn and charles j. General thermodynamic considerations when an electrophilic substitution at saturated carbon occurs, either a carbanion is liberated as such or, if no carbanion is actually formed, the carbon atom undergoing substitution has a certain amount of carbanion character. Use a reactive species, whether strong anion or an acid, to start the first step a. Carbanions are formally derived from neutral organic molecules by removal of positively charged atoms or groups of atoms, and they are important chiefly as chemical intermediatesthat is, as substances used in the preparation of other substances. J cram, fundamentals of carbanion chemistry academic press, new york. In an sel reaction, a carbanion intermediate is formed in the ratedetermining step. Journal of the american chemical society vol 98, no 25. Therefore, there is a lack of correlation between the rate of decarboxylation and the gasphase stability of resulting carbanions. If the carbanion intermediate is oxidatively trapped by flavin, the reaction can be readily diverted to the oxidation reaction, leading to a. In c, the carbanion is primary, but in a, it is secondary. The overall result is that fluorinated carbanions are pyramidal and therefor stabilized by the fluorine. Publication date 1965 topics carbanions publisher new york, academic press. Cram, fundamentals of carbanion chemistry, academic press 1965. Fundamentals of carbanion chemistry cram, donald j.
Carbanion definition of carbanion by merriamwebster. Pdf preparation and reaction of several delocalized. The number of protons plus the number of neutrons in an atom of an element, measured in atomic mass units amu. Fluorine backbonding would be just the opposite in donating electrons to the carbanion center, and thus be destabilizing. Accounts of chexical research volume 1 number 2 february, 1968 the chemistry of cyclopropanols c. Palm desert, california, 17 june 2001, physical organic chemistry. Love professor crams early research was in physical organic chemistry, where his notable contributions included the structure and intermediacy of phenonium ions in solvolysis reactions, the stereochemistry of carbanions in 1965 he wrote a monograph fundamentals of carbanion chemistry, and the stereochemistry of carbonyl addition reactions crams rule. Fundamentals of carbanion chemistry by cram, donald j. Use of the sel reaction to study carbanions involves three constitutional. References abbott ap, capper g, davies dl, rasheed rk, tambyraja y. Some basic concepts in radical chemistry radicals are species atoms, molecules, ions which contain an unpaired electron, r. Love professor cram s early research was in physical organic chemistry, where his notable contributions included the structure and intermediacy of phenonium ions in solvolysis reactions, the stereochemistry of carbanions in 1965 he wrote a monograph fundamentals of carbanion chemistry, and the stereochemistry of carbonyl addition reactions cram s rule. Download it once and read it on your kindle device, pc, phones or tablets.
Cram, fundamentals of carbanion chemistry, academic press, new. Generation of the enolate of acetaldehyde from noncarbonyl substances and its calkylation, 0acylation and 0silylation michael e. A twostep mechanism has been proposed in which an equilibrium leading to the. Chapter 2 the formation and reactions of carbanions 1. Study of the stability of the corresponding carbanions 79 in the gas phase have found that carbanion 7 is 7 kcalmol more stable than either carbanion 8 or 9 table 1 6, 7. Radicals and carbocations prefer a greater degree of alkyl substitution. Unsuccessful attempts to determine an acid dissociation constant of. A within the broad theory of organic chemistry, one of the more fundamental problems. Organic chemistry fundamentals of carbanion chemistry. The required energy for the planarization of the ion 1 d. Carbanion, any member of a class of organic compounds in which a negative electrical charge is located predominantly on a carbon atom. Carbanion definition is an organic ion carrying a negative charge on a carbon atom. Chapter 2 the formation and reactions of carbanions. Carbanions and other carbon nucleophiles springerlink.
Ccdc1824208 contains the supplementary crystallographic data for this paper. Fundamentals of carbanion chemistry provides information pertinent to carbanion chemistry. Dynamics of proton transfer involving delocalized negative ions in the gas phase. Fundamentals of organic chemistry carbohydrates organic and biochemistry for today4th ed. Introduction to organic chemistry, macmillan publishing co. Slabaugh 2 carbohydrates and biochemistry carbohydrates are compounds of tremendous biological importance. It is important to know the hierarchy of reaction intermediates such as radicals, carbocations, carbanions. A carbanion is a reactive intermediate and is encountered in organic chemistry for instance in the e1cb elimination reaction and in organometallic chemistry in for instance a grignard reaction or in alkyl lithium chemistry. Pedersen for their development and use of molecules with structurespecific interactions of high selectivity. Electron transfer to and from molecules containing. The presence of fluorine on the aromatic moiety precludes the normal rearomatization process. A carbanion is an anion in which carbon is trivalent forms three bonds and bears a formal negative charge in at least one significant resonance form.
Both carbocations and radicals have the same pattern. Chemists, organic chemists, researchers, and graduate students interested in the field of carbanion chemistry will find this book extremely useful. Carbanions from decarboxylation of orotate analogues. While the substitution of hydrogen with metals in certain hydrocarbons acetylene 1, phenylacetylene 2, triphenylmethane 3, diphenyl methane 4, cyclopentadiene 5, fluorene 6 has been a known reaction for 100 years, it was not until the turn of the century that acidity was made responsible for this phenomenon. Therefore, there is a lack of correlation between the rate of decarboxylation and the gasphase stability of resulting carbanions 7. This book explores several topics, including carbonium ions, carbanions, carbenes, and carbon radicals. Infrared spectroscopic study of the chemical composition of unsaturated acid structural isomers. The transition towards the planar conformation 90 causes an increase in the energy of the ion. Cram, fundamentals of carbanion chemistry, academic. This is a pdf file of an unedited manuscript that has been accepted for publication. Cram, fundamentals of carbanion chemistry, academic press, new york, 1965.
No correlation between the stability of the carbanions and the rate of. Fundamentals of carbanion chemistry 1st edition elsevier. Supporting information for this article is given via a link at the end of the document. This result was explained in terms of both the ease of carbanion formation from rmgbr and the activity of the anion formed.
Fundamentals of carbanion chemistry textbook binding june 1, 2000 by cram, author see all 4 formats and editions hide other formats and editions. Here we present a quick guide to reaction intermediate hierarchies. They were the founders of the field of hostguest chemistry. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. New york, academic press, 1965 dlc 65022772 ocolc543641. Electron transfer to and from molecules containing multiple. Purchase fundamentals of carbanion chemistry 1st edition. A life in pictures, ucla department of chemistry and biochemistry. The final chapter considers the unsaturated anionic rearrangements of carbanions, carbonium ions, as well as carbon radicals and other rearrangements. This thesis describes some 3,3 and 2,3 sigmatropic rearrangements that can occur in a variety of polyfluoroaromatic and heteroaromatic compounds. In addition, for each carbanion the cf 3 groups of neighboring triflyl groups lie trans to one another.
Carbanions prefer a lesser degree of alkyl substitution. Use features like bookmarks, note taking and highlighting while reading fundamentals of carbanion chemistry. Depuy department of chemistry, university of colorado, boulder, colorado 80308 received june 18, 1967 cyclopropanols have been principally synthesized by 1 reaction of epichlorohydrins with magnesium bromide followed by treatment with grignard reagent and ferric. The very high degree of stereospecificity observed in these basecatalyzed open ings argues against free carbanions. Fundamentals of carbanion chemistry kindle edition by donald j. Reactivities of grignards reagent hexamethylphosphoramide.
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