Stable carbonium ions.  XLV.  Benzyl cations

Bollinger, J. Martin; Comisarow, Melvin B.; Cupas, Chris A.; Oláh, George A.

doi:10.1021/ja00998a034

Cited by 44 publications

(25 citation statements)

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“…2,6-Bis (3,5-di-tert-butylbenzylammoniummethyl)naphthalene bis(hexafluorophosphate) (3´2 PF 6 ): 2,6-Naphthalenedicarboxaldehyde [26] (139 mg, 0.76 mmol) was condensed with 3,5-di-tert-butylbenzylamine [27] (332 mg, 1.52 mmol) to provide 2,6-bis (3,5-di-tert-butylbenzylideneaminomethyl 4, 35.0, 48.3, 49.9, 123.3, 124.5, 127.9, 128.9, 129.7, 130.0, 132.4, 151.9, 152.0 1,5-Bis(3,5-di-tert-butylbenzylammonium)pentane bis(hexafluorophosphate) (4´2 PF 6 ): Condensation of 3,5-di-tert-butylbenzaldehyde [25] (3.00 g, 13.7 mmol) with 1,5-diaminopentane (0.70 g, 6.8 mmol) furnished 1,5-bis (3,5-di-tert-butylbenzylidene) 38 (br, 38 H), 1.85 ± 1.95 (m, 4 H), 2.71 (m, 4 H), 3.96 (s, 4 H), 7.42 (m, 6 H); 13 C NMR (CDCl 3 ): d 24.4, 26.5, 31.5, 35.2, 46.2, 51.7, 123.0, 129.1, 129.9, 152.0 4,4' '-Bis (3,5-di-tert-butylbenzyl)bipyridinium bis(hexafluorophosphate) (6´2 PF 6 ): An MeCN (30 mL) solution of 4,4'-bipyridine (1.00 g, 6.4 mmol) was added dropwise with stirring to a hot solution of 3,5-di-tert-butylbenzyl bromide [28] (7.26 g, 25.6 mmol) in MeCN (30 mL). The reaction mixture was further stirred and heated under reflux for 36 h. Upon cooling, the resulting yellow precipitate was collected and air-dried.…”

Section: H)mentioning

confidence: 99%

Doubly Docked Pseudorotaxanes

et al. 1998

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Section: H)mentioning

confidence: 99%

Doubly Docked Pseudorotaxanes

et al. 1998

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“…Studying the structural properties and reactivities of benzyl cations is a subject of fundamental importance. Experimental observation supported by theoretical calculations indicates that two major resonance forms, as shown in Scheme 1, contribute significantly to the total electronic structure of the benzyl cation [1][2][3][4][5][6]. The well-known reactivity of benzyl cation is electrophilicity due to the phenylmethyl cation character.…”

Section: Introductionmentioning

confidence: 99%

“…They are usually short-lived in solution and so it is difficult to characterize their properties in solution. They can be stabilized only under super-acidic conditions at low temperatures [2,3] or by coordination to a metal center [4,5]. Studying the structural properties and reactivities of benzyl cations is a subject of fundamental importance.…”

Section: Introductionmentioning

confidence: 99%

Gas-Phase Chemistry of Benzyl Cations in Dissociation ofN-Benzylammonium andN-Benzyliminium Ions Studied by Mass Spectrometry

Chai

Wang

Sun

et al. 2012

J. Am. Soc. Mass Spectrom.

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In this study, the fragmentation reactions of various N-benzylammonium and N-benzyliminium ions were investigated by electrospray ionization mass spectrometry. In general, the dissociation of N-benzylated cations generates benzyl cations easily. Formation of ion/neutral complex intermediates consisting of the benzyl cations and the neutral fragments was observed. The intra-complex reactions included electrophilic aromatic substitution, hydride transfer, electron transfer, proton transfer, and nucleophilic aromatic substitution. These five types of reactions almost covered all the potential reactivities of benzyl cations in chemical reactions. Benzyl cations are well-known as Lewis acid and electrophile in reactions, but the present study showed that the gas-phase reactivities of some suitably ring-substituted benzyl cations were far richer. The 4-methylbenzyl cation was found to react as a Brønsted acid, benzyl cations bearing a strong electron-withdrawing group were found to react as electron acceptors, and parahalogen-substituted benzyl cations could react as substrates for nucleophilic attack at the phenyl ring. The reactions of benzyl cations were also related to the neutral counterparts. For example, in electron transfer reaction, the neutral counterpart should have low ionization energy and in nucleophilic aromatic substitution reaction, the neutral counterpart should be piperazine or analogues. This study provided a panoramic view of the reactions of benzyl cations with neutral N-containing species in the gas phase.

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“…Optimized complex geometries were calculated from a minimum of 500 different starting geometries by the use of the MonteCarlo (MC) algorithm. A solution of 4,4'-bipyridine (1.7 g, 11.0 mmol) and 1-bromomethyl-3,5-di-tert-butylbenzene [19] in acetonitrile (20 mL) was heated under reflux for 3 h. After cooling to room temperature the solidified reaction mixture is diluted with dichloromethane (50 mL), and the yellow dibromide 12·2Br -(7.5 g, 95%) is filtered off and dried in vacuo. For the anion exchange the crude 12 ·2Br -(0.50 g, 0.78 mmol) was suspended in water (20 mL), and methanol was added slowly until all of the dibromide is dissolved.…”

Section: Molecular Mechanics Calculationsmentioning

confidence: 99%

Molecular tweezers as synthetic receptors: molecular recognition of cationic substrates; an insight into the mechanism of complexation

Kamieth¹,

Klärner²

1999

J. prakt. Chem.

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245Aromatic molecules play an important role in many areas of biological and supramolecular chemistry [1] and their noncovalent interactions with other aromatic units (π-π-or arene-arene interaction) [2] and positively charged ions (cation-π interaction) [3] are of particular importance in the formation of superstructures [2][3][4] The design of efficient synthetic receptors with the ability to selectively bind substrates in solution requires precise control of both their electronic and topological properties. Besides the frequently used cyclic receptors of the cyclophane-type [5] non-cyclic receptors with cavities of flexible size proved to be very effective [6]. We have recently reported on the synthesis and some supramolecular properties of the hydrocarbon compounds 1a and 1b, which due to their ability to selectively bind electron-deficient aromatic and aliphatic substrates as well as organic cations can be regarded as molecular tweezers [7]. Here we report on the binding properties of the benzene-spaced molecular tweezers 1a towards various aliphatic and aromatic cations in organic solution and attempts to use this binding motive for the template synthesis of mechanically interlocked supermole- Molecular Tweezers as Results and DiscussionDue to the ribbon-type concave topology the five benzene units of molecular tweezer 1a define a cavity in which a substrate can be bound by multiple noncovalent interaction. The magnetic anisotropy of these benzene units makes the 1 H NMR spectroscopy to be a very sensitive probe to detect the complexation of substrate molecules bound inside the cavity of 1a [7]. From the results obtained in binding studies with small electrondeficient aliphatic substrates (CH 3 CN, CH 2 (CN) 2 , CH 3 NO 2 ) [7a] and intramolecular complexation of flexible aliphatic sidechains [7b] we already know that the cavity of 1a has an almost ideal size for the binding of methyl or methylene groups. Because of the very electron-rich character of the tweezer's concave side [9] we supposed that ammonium ions also should be suitable substrates due to multiple cation-π interactions with the host 1a.Due to the different solubility properties of the hydrocarbon 1a and ionic substrates only CDCl 3 and mixtures of CDCl 3 and (CD 3 ) 2 CO (v/v 1:1 or 1:2) can be used as solvents. Most of the primary ammonium ions, however, are nearly insoluble in CDCl 3 or CDCl 3 / (CD 3 ) 2 CO mixtures even as PF 6 -salts. Therefore, we performed 1 H NMR bindings studies only with the better soluble secondary ammonium salts, di-n-butylamguest molecule enters the tweezer's cavity through the open sides of the host, a second mechanism is available in which the substrate enters the cavity through a gap emerging after a substantial spreading of the tweezer's tips by at least of about 280 pm. n 1 (n = 0) 2 (n = 1) 1a (n = 0) 1b (n = 1)

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Stable carbonium ions. XLV. Benzyl cations

Cited by 44 publications

References 0 publications

Doubly Docked Pseudorotaxanes

Doubly Docked Pseudorotaxanes

Gas-Phase Chemistry of Benzyl Cations in Dissociation ofN-Benzylammonium andN-Benzyliminium Ions Studied by Mass Spectrometry

Molecular tweezers as synthetic receptors: molecular recognition of cationic substrates; an insight into the mechanism of complexation

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