Homopolar and Heteropolar Bond Dissociation Energies and Heats of Formation of Radicals and Ions in the Gas Phase II. The relationship between structure and bond dissociation in organic molecules

Egger, Kurt W.; Cocks, Alan T.

doi:10.1002/hlca.19730560510

Cited by 42 publications

(13 citation statements)

References 32 publications

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“…Figures 2 and 3), indicate an enhanced complexity for the fluorinated analogues. At first sight this might appear to be contrary to what would be expected given that fragmentation processes such as the loss of HF compared with H 2 are effectively thermolytically equivalent [25]. The behavior, and hence prediction, of the mass spectra of polyfluroinated materials, when compared to their hydrocarbon counter parts, appears to be fraught with difficulty.…”

Section: Resultsmentioning

confidence: 87%

Chemical ionization pathways of polyfluorinated chemicals—A connection to environmental atmospheric processes

Ellis

Mabury

2003

J. Am. Soc. Mass Spectrom.

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A systematic mass spectrometry study of an industrially prolific class of polyfluorinated compounds known as telomers was conducted. The study specifically focused upon polyfluorinated alcohols along with corresponding saturated and ␣,␤-unsaturated fluoroacids. Within each class differing fluoroalkyl chain length homologues were investigated, using negative and positive chemical ionization mass spectrometry (NCI and PCI). In the case of the fluoroalcohols, NCI resulted in the production of more elaborate spectra than the other classes. Moreover, it showed the interesting production of HF 2 Ϫ and the complex of this species, along with F Ϫ , with the parent molecule. These complexes resulted in the formation of the novel H 2 F 3 Ϫ ion. Results show that there is significant intra-molecular hydrogen bonding that occurs for these compounds, which influences the molecules fragmentation. This bonding will also influence the fate and disposition through environmental processes (e.g., V P , k OH , K OW , K OA ) which are affected by molecular geometry. Furthermore, there is an increased accumulation and persistence potential for the molecule as a function of the fluorocarbon chain length. We have shown that in conjunction with the use of mass spectroscopy the engertics of environmental processes for polyfluorinated materials can be

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Section: Resultsmentioning

confidence: 87%

Chemical ionization pathways of polyfluorinated chemicals—A connection to environmental atmospheric processes

Ellis

Mabury

2003

J. Am. Soc. Mass Spectrom.

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“…In case of a homopolar and effectively complete C-H bond breaking in the transition state, a maximum effect of about 12.5 kcalimole from the gain in allylic stabilization energy [15] would be expected for vinyl substituents. To a first approximation it may then be concluded that in the transition state, the C-H-bond is broken to 50% or greater.…”

Section: Discussionmentioning

confidence: 99%

“…It is important to keep in mind that vinylsubstituents are expected to stabilize (via polarizability stabilization [25]) ensuing positive charges on the carbon atom Y [eq. (7)] by about as much [15] as emerging radical sites. A partial heteropolar C-H bond rupture, i.e., a pronounced polar character of the transition state would also be reconcilable with the observed difference in E, of -5 kcal/mole.…”

Section: Discussionmentioning

confidence: 99%

Thermochemical kinetics of nitrogen compounds. V. The unimolecular thermal decomposition of diallylamine in the gas phase

Egger¹,

Vitins

1974

Int J of Chemical Kinetics

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The kinetics of the thermal decomposition of diallylamine to propylene and prop-2-enaldimine have been studied in the gas phase in presence of an excess of methylamine over the temperature range of 532.7 to 615.6"K, using a static reaction system. Methylamine reacted with the unstable primary product prop-2-enaldimine, forming the thermally stable N-methyl prop-2-enaldimine.First-order rate constants, based on the internal standard technique, fit the Arrhenius relationship log kfs-1) = (1 1.04 f 0.13) -(37.1 1 f 0.33 kcal/mole)/2.303 RT. They were independent on the initial total pressure (46-340 torr), the initial pressure of diallylamine (9.2-65 torr), or methylamine as well as the conversion attained. Despite an apparent surface sensitivity, the reaction is essentially homogeneous in nature as demonstrated by experiments carried out in a packed reaction vessel. The observed activation parameters for the title reaction together with those observed earlier for triallylamine and allylcyclohexylamine are consistent with the proposed concerted reaction mechanism involving a cyclic 6-center transition state. The observed substituent effects suggest a nonsynchronous mode of bond breaking and bond formation. Jn troductionT h e thermal decomposition of diallylamine has been investigated as part of a series of studies on the thermochemical kinetics of N-substituted N-allylamines in a n attempt to obtain more information about the effect of substituents and heteroatoms on the concerted nature of the common reaction mechanism, involving a 6-center transition state complex as indicated in eq. Research, 5303 Wurenlingen, Switzerland. EGGER AND VITINSOf particular interest is the question of the extent of nonsynchronous bond breaking and bond formation, i.e., the amount of polar character in the ground and transition states.To this end we have so far reported measurements on N-allyl-N-cyclohexylamine [ 1 ] and triallylamine [2] and are presently investigating N-allyl-N-methylamine and N-allyl-N-methylaniline, as well as 1,6-hexadiene.Experimental Materials N-diallylamine (DAA) and toluene (T) (used as an internal standard) were obtained from Fluka Chemical Corporation, Buchs, Switzerland. After distillation, DAA was found by gas chromatography (GC) to be 99.0% pure, containing one major light impurity which proved to be thermally stable at the reaction conditions used and did not interfere in the analysis of the product mixture.Two starting mixtures (denoted by A and B ) with mole ratios DAA/T of 0.928 and 0.855, respectively, have been used. The mixtures were stored under nitrogen and gave GC analyses reproducible within =t0.6% over the period of several weeks.Methylamine, supplied by Fluka Chemical Corporation, was purified by distillation and stored as a gas in a 2-1. bulb. GC analyses showed it to be 98% pure. The observed impurities did not affect the analysis of the starting or product mixture. Apparatus and procedureThe static high vacuum system and general procedures used for the kinetic studies were essenti...

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“…3 which illustrates the results of the thermochemical estimates discussed above. The differences between the calculated energies of the isomeric biradicals 21 to 23 arise largely from the different stabilization energies attributed to allylic (Es = 9.6 kcal/mol) and propargylic (E, = 6.5 kcal/mol) resonance [35]. The precursor of 1, biradical21, is calculated to be less stable than 22 and 23.…”

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confidence: 98%

1,5‐Cyclooctadiyne. Preparation and Reactivity

Kloster‐Jensen

Wirz

1975

Helvetica Chimica Acta

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Kfingclbergstrasee 80, CH-4056 Basel. Switzcrlmd (20. XI. 74) Summauy. 1,.5-Cyclooctadiyne 1 was isolated in 2 pcrcent yield from polymerized butatrieno 5. Other oligomcrs of 5 wcre dctected in the reaction mixture by combined GLC./MS. analysis but have not been identified. Diets-Aldev adducts of I with two equivalents of 1,J-butadiene and of 2,3-dimethyI-l.J-butarli~ne have bcan preparcd. In the prescnce of strong base 1 isomorizcd to cyclooctatctraenc. 5 was rcformcd by photolysis of 1. Attcmpts to preparc transition mctal complexes of 1 failed. Effrxts of ring strain and of transannular interaction on the rcactivity of 1 arc discusscd. The dirnerization of 5 to 1 is predicted to be strongly cxothcrmic.The synthesis of medium-sized cyclic alkynes [l] and the investigation of their chemical reactivity as a function of geometric ring strain have been the object of considerable effort during the past twenty years. The smallest unsubstituted cycloalkyne yet isolated is cyclooctyne which was first prepared by Bloquist in 1953 [2], Evidence for the intermediate existence of the lower homologues cycloheptyne, .-hexyne, and -pentyne is limited to trapping and self-trapping reactions [3aJ. ' 1 2 3 4 ---1) Permanent addrcss:

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Homopolar and Heteropolar Bond Dissociation Energies and Heats of Formation of Radicals and Ions in the Gas Phase II. The relationship between structure and bond dissociation in organic molecules

Cited by 42 publications

References 32 publications

Chemical ionization pathways of polyfluorinated chemicals—A connection to environmental atmospheric processes

Chemical ionization pathways of polyfluorinated chemicals—A connection to environmental atmospheric processes

Thermochemical kinetics of nitrogen compounds. V. The unimolecular thermal decomposition of diallylamine in the gas phase

1,5‐Cyclooctadiyne. Preparation and Reactivity

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