The chemistry of ylids—V

Johnson, Alice; LaCount, R.B.

doi:10.1016/0040-4020(60)80061-0

Cited by 75 publications

(32 citation statements)

References 19 publications

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“…In every instance replacement of methyl ,In ref. 10 we reported 9-fluorenyldin~ethylsulfonium bromide (5) to be slightly more acidic than 9-fluorenyltriphenylphosphoniuin bromide (6). Using our new solvent system (7) and checking these results we havenow found that the pK, of 5 is 11.4 while that of 6 is 8.9, the latter as reported in ref.…”

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The chemistry of ylids. XVI. The acidifying effects of 'onium groups

Johnson¹,

Amel²

1968

Can. J. Chem.

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NOTES 461analytically pure material was 0.15 g (81 %), m.p. 153-154" (decamp.).Anal. Calcd. for C15H18N305S2: C, 48.65; H, 4.86. Found: C, 48.52; H, 5.02. Cotlversion of the Toluenesulfor~ic Acid Salt toAnl~ydrober~zylpet~icilli~z The salt 3 (100 mg, 0.27 mmoles) was suspended in methylene chloride (2ml) and an ice-cold saturated sodium bicarbonate solution (2 ml) was added. The salt dissolved when this mixture was shaken. The yellowish aqueous layer was removed and the methylene chloride layer was passed through a short column of anhydrous sodium sulfate. The column was washed with methylene chloride and the dry solution of the base 4 (volume, 3 ml) was treated with a solution of phenylacetic acid (37 mg, 0.27 mmole) in methylene chloride (1 ml) and then with a solution of diisopropylcarbodiimide (34 mg, 0.27 mmole) in methylene chloride (1 ml). The reaction mixture was left for 20 h at room temperature and the solvent was then removed. The crystalline residue was triturated with ether and the ether-insoluble material was recrystallized twice from isopropyl alcohol, giving 43 mg (52 % from 3) of anhydrobenzylpenicillin, n1.p. 148-15O0, identical with the compound prepared from Penicillin G on the basis of its infrared spectrum and an undepressed mixture melting point. An examination of the pK,'s of a series of phenacyl 'onium salts has indicated that the acidifying effects of the 'onium groups increase in the order arsonium < phosphonium < sulfonium. The acidifying effects of the 'onium atom substituents increase in the order methyl < 11-butyl < phenyl. These observations have been accounted for in terms ofprc-rlx overlap between the carbanion and the heteroatom of the 'onium group.Canadian Journal of Chemistry, 46,461 (1968) The discovery and use of ylids containing a variety of heteroatom groups has given rise to questions regarding the relative effectiveness with which the different 'onium groups (X in 2) provide stabilization for the adjacent carbanion.It is well recognized, especially on the basis of infrared (1) and x-ray crystallographic (2) evidence on phenacylides (4), that considerable 'For part XV in this series, see A. W. Johnson and S. C. K. Wong, Can. J. Chem. 44, 2793Chem. 44, (1966.2Author to whom inquiries should be addressed at The Chemistry Department, University of North Dakota, Grand Forks, North Dakota, U.S.A. stabilization is afforded the carbanion by delocalization of the negative charge through the carbon portion of the ylids (i.e. through the carbonyl group in 2). However, it also appears that the 'onium group (X in 2) must provide conjugative stabilization of the carbanion in order for such ylids to have any finite existence. The stabilization probably is via pn: -dn: overlap between the carbanion and the 'onium group if the latter has available empty, low-energy d-orbitals (3). Such is the case with arsonium, phosphonium, and sulfonium ylids.We wish to report some recent pKa determinations which indicate the relative effectiveness of the groups X in increasing the acidity of the...

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The chemistry of ylids. XVI. The acidifying effects of 'onium groups

Johnson¹,

Amel²

1968

Can. J. Chem.

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“…This can be explained by extended conjugation of three phenyl rings of phosphine moiety when compared with n-butyl groups. 33,34 It is also supported by the higher d value of methine proton of 1a (at 6.82 ppm) in comparison of 2a (at 5.77 ppm) in 1 H-NMR spectra. The higher shift in d value of methine proton can be correlated with higher acidity, which is related to the initiator activity.…”

Section: Effect Of Phosphine Moietymentioning

confidence: 66%

“…This compound was prepared in same manner as described for 1 and followed by anion exchange with NaSbF 6 in MeOH-H 2 To the solution of dibenzo(a,d)cyclohepten-5-yl chloride (10 mmol, 2.28 g) in toluene (20 mL), Ph 3 P (10 mmol, 2.62 g) in toluene (15 mL) was added at ambient temperature and allowed to stir for 30 min. The resulted white precipitate was filtered, washed with toluene, and counter anion was exchanged with NaSbF 6 in same manner as described for 1a and recrystallized with ethanol-CH 2 34.50 mg) was placed in a flame-dried ampoule equipped with three-way stopcock connected to manifold and degassed for 30 min with three freeze-pump-thaw cycles and sealed off. The ampoule was immersed in an oil bath for the required time and temperature.…”

Section: Synthesis Of 5-h-dibenzo(ad)cyclohepten-5-yl Tri-nbutylphosmentioning

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Novel dibenzocycloheptenyl phosphonium salts as thermolatent initiator in cationic polymerization

Gupta

Singh

2009

J of Applied Polymer Sci

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In this study, novel thermolatent cationic initiators based on dibenzocycloheptenyl phosphonium salts (1a, 1b, 1c, 1d, 2a, and 3a) were synthesized and their efficiency was examined in bulk polymerization of glycidyl phenyl ether (GPE). The polymerization of GPE was performed with 1 mol % of dibenzocycloheptenyl triphenylphosphonium salts (1a-1d) with different counter anions (SbF 6 À , PF 6 À , AsF 6 À , and BF 4 À ) at 25-200 C for 1 h. The order of initiator activity was found as 1a > 1d > 1b > 1c . To examine the effect of phosphine moiety, the activity of 1a was compared with dibenzocycloheptenyl-tri-nbutylphosphonium hexafluoroantimonate (2a). The order of initiator activity was observed as 1a > 2a. The initiator activity of 1a was compared with that of 10,11-dihydrodibenzocycloheptenyltriphenylphosphonium hexafluoroantimonate (3a) to understand the effect of extended conjugation in dibenzocycloheptenyl ring. In general, with the increase in the polymerization temperature, conversion (%) also increases. The solubility of initiators in various solvents and epoxy monomers was also examined.

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“…3a to 3c, 3e to 3g, 3 j to 3k) led to a decrease in the pKa of the salt, usually by about one pK, unit. Thereby were provided additional examples of an effect first noted by us in 1960 (10) and subsequently amplified in our more recent work (7). This increase in acidity has been attributed by us (7) to the powerful inductive withdrawal effect of the phenyl group (relative to alkyl) which decreases the electron density on the heteroatom.…”

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“…Fliszar et al (6) have demonstrated such a quantitative relationship, but only within the triphenylphosphoniumphenacylide series (2, X = (C,H,),P). However, for some as yet unknown reason, this kind of relationship seems not to hold between dimethylsulfoniumfluorenylide and triphenylphosphoniumfluorenylide in light of their new pK, values (10). We are exploring this aspect further.…”

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Fluoranthene studies. III. A synthesis of 3-bromo-6-nitrofluorenone

Charlesworth¹,

Mathiaparanam²

1968

Can. J. Chem.

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A synthesis of 3-brorno-6-nitrofluorenone has been accomplished by the diazotization and Pschorr cyclization of 2-amino-4-bromo-4'-nitrobenzophenone, the synthesis of which is described. The identity of the above bromonitrofluorenone with the degradative oxidation product of 9-bromo-2-nitrofluoranthene establishes unequivocally the structure of the latter substance.Canadian Journal of Chemistry, 46, 463 (1968) By degradative oxidation of what was presum-unrecorded brornonitrofluorenone. Other eviably 9-bromo-2-nitrofluoranthene (I), Charles-dence suggested that the bromine was in the worth and Dolenko (1) obtained a previously 9-position of the fluoranthene nucleus and thus Can. J. Chem. Downloaded from www.nrcresearchpress.com by 54.244.106.145 on 05/11/18For personal use only.

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The chemistry of ylids—V

Cited by 75 publications

References 19 publications

The chemistry of ylids. XVI. The acidifying effects of 'onium groups

The chemistry of ylids. XVI. The acidifying effects of 'onium groups

Novel dibenzocycloheptenyl phosphonium salts as thermolatent initiator in cationic polymerization

Fluoranthene studies. III. A synthesis of 3-bromo-6-nitrofluorenone

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