Kinetics and mechanism of gas-phase pyrolysis of ylides. Part 3.<sup>1</sup>Thermal reactivity of<i>α</i>-carbonyl- and thiocarbonyl-stabilized methylenetriphenylphosphoranes
作者:Rasha F. Al-Bashir、Nouria A. Al-Awadi、Osman M. E. El-Dusouqui
DOI:10.1002/poc.1752
日期:2011.4
Fourteen ketone/thione‐stabilized triphenylphosphonium methylides were subjected to conventional gas‐phase and flash vacuum pyrolysis (FVP). The kinetics of the first‐order thermal gas‐phase reactions of all these compounds were investigated over 360–653 K temperature range. The values of the Arrhenius log A and energy of activation of these ylides averaged 11.52 ± 0.34 s−1 and 133.20 ± 3.14 kJ mol−1
The Wittig-type Reaction of O=C–, C=C–, and N=C–Substituted Methylenetriphenylphosphoranes with<i>N</i>-Sulfinyl-<i>p</i>-toluenesulfonamide. An Intramolecular 1,3-Dipolar Cyclization of Imidoylconjugated Thione<i>S</i>-Imides
The Wittig-type reactions of N-sulfinyl-p-toluenesulfonamide with (1) O=C–, (2) C=C–, and (3) N=C-conjugated phosphorus ylides were investigated. In the reaction with (1), N-sulfinyl-p-toluenesulfonamide reacted at both the ylide and the carbonyl moiety to form TsN=C-conjugated thione S-imide, which underwent intramolecular 1,3-dipolar cycloaddition of the CSN group with the aromatic C=C bond of the tosyl
The reaction of the stabilisedylides 14–23 with an excess of NO2 in CH2Cl2 at room temperature gives different results depending on the structure of the starting ylide. The monacyl ylides 14–16 give the corresponding α-oxo nitriles 4 together with Ph3PO · HNO3 (24) which has been fully characterised for the first time. Under the same conditions, the ylide 18 gives 2,4-dinitrobenzonitrile (26), Ph3PO
Phosphonium salts and phosphoranes. Part 5. Thermal and electron-impact induced fragmentation of heteroaroylmethylenetriphenylphosphoranes.
作者:Judith M. Brittain、R.Alan Jones、Sayed Ali Naghi Taheri
DOI:10.1016/s0040-4020(01)90373-4
日期:1992.9
synthesis of five-membered heteroarylethynes. The electron-impact induced fragmentation of the phosphoranes also produced ions corresponding in mass to the ethynes, but metastable ion data indicate that the extrusion of the ethyne follows the initial loss of H· from the molecularion.
Solvent-free mechanochemical preparation of phosphonium salts, phosphorus ylides, and olefins
申请人:Iowa State University Research Foundation, Inc.
公开号:US20030176740A1
公开(公告)日:2003-09-18
The present invention provides a method of preparing a phosphonium salt of the formula [R
1
R
2
R
3
P—CR
4
R
5
R
6
]X, comprising ball-milling a phosphine of the formula R
1
R
2
R
3
P with a compound of the formula XCR
4
R
5
R
6
; a method of preparing a phosphorus ylide of the formula R
1
R
2
R
3
P═CR
4
R
5
, comprising ball-milling a phosphonium salt of the formula [R
1
R
2
R
3
P—HCR
4
R
5
]X in the presence of a base; and a method of preparing an olefin of the formula R
4
R
5
C═CR
7
H or R
4
R
5
C═CR
7
R
8
, comprising ball-milling a phosphorus ylide of the formula R
1
R
2
R
3
P═CR
4
R
5
with a compound of the formula R
7
C(O)H or R
7
C(O)R
8
. The inventive method produces phosphonium salts and phosphorus ylides by mechanical processing solid reagents under solvent-free conditions. The advantages of the present invention over conventional solution methods, include: (1) extremely high selectivity; (2) high yields; (3) low processing temperatures; (4) simple and scalable reactions using commercially available equipment; and (5) the complete elimination of solvents from the reaction.