Amide stability

As the formation of betaines from amide-stabilized ylides is known to be reversible (in contrast with aryl- or semistabilized ylides, which can exhibit irreversible anti betaine formation see Section 1.2.1.3), the enantiodifferentiating step cannot be the C-C bond-forming step. B3LYP calculations of the individual steps along the reaction pathway have shown that in this instance ring-closure has the highest barrier and is most likely to be the enantiodifferentiating step of the reaction (Scheme 1.16) [25]. 

A more recent example is the twisted amide (2) devised by Kirby, which despite the lack of electron-withdrawing groups (other than nitrogen) is completely hydrated upon protonation on nitrogen here the amide is unable to delocalize the nitrogen electrons onto the carbonyl, which means there is none of the usual amide stabilization. 

Problems resulting from precipitation when solutions of compound 4 underwent addition of anions prevented an accurate titration data set from being collected, however a direct comparison was possible between compounds 1 and 3, for which ll NMR titrations which could be titrated under the same solvent (CD3CN). The comparison of the binding data revealed a significant reduction in the stability constants for oxo-anions of the mono-amide relative to the bis-amide (stability constants for dihydrogen phosphate and benzoate for 1 [3.6 x 102 M 1 and 2.5 x 103 M"1] whilst association constants for 3 with the same anions [8.9 x 101 M 1 and 2.0 x 102 M 1]). This important... 

The first reaction of aminals with sulfur ylides to afford aziridines has been reported <070L2099>. The Ellman /er/-butylsulfinyl auxiliary group provided up to greater than 95 5 dr for trans and always greater than 95 5 dr for cis when allyl-, aryl-, and amide-stabilized ylides were employed. 

An ethoxylated alkyl sulfate with small amounts of amide stabilizers was used at concentrations (in the aqueous phase) of 0.5, 1.0, and 1.5%. The air-to-aqueous phase ratio (at reservoir pressure) was 10 1. Two types of tests were performed (1) alternate injections of surfactant solution and air, as in WAG (water alternating with gas) cycles and (2) simultaneous injections of air and surfactant solution, using the foam generator. Diagnostic chemical tracer injections were used before and after the tests. 

A. M. Heras-Lopez, M. S. Pino-Gonzalez, F. Sarabia-Garcia, and F. J. Lopez-Herrera, Reaction of O-benzyl- and 4,6-benzylidene-D-gluco- and D-galactopyranose derivatives with amide-stabilized sulfur ylides, J. Org. Chem., 63 (1998) 9630-9634. 

How shall we represent the stabilization Comparing again with the amide stabilization, you might think about how to represent it with curly arrows this is straightforward with the amide and you have seen it many times. But it looks odd with our heterocycle electron density moves... 

Sodium phthalate stearyl amide stabilizer, emulsion mousses PVM/MA copolymer, isopropyl ester stabilizer, emulsion nonalcoholic beverage flavoring oils... 

Foam also has been tested as a way to modify the permeability profile in injection wells in a waterflood. More than 100 surfactants were tested for this purpose, and it was found that certain ethoxylated alkyl sulfates containing amide stabilizers were efficient foaming agents. For the field test, a modified ammonium lauiyl sulfate called O.K. Liquid was used. 

Sodium phthalate stearyl amide Stabilizer, emulsions emulsion conditioners... 

Sodium phthalate stearyl amide stabilizer, emulsions moisturizing sunscreens... 

Emalex GWS-310 Emalex GWS-320 Stabilizer, emulsions o/w creams TEGO Carbomer 134 Stabilizer, emulsions o/w emulsions LInoleamIde DEA Schercomid SLE Sodium phthalate stearyl amide Stabilizer, emulsions o/w lotions TEGO Carbomer 141 Stabilizer, emulsions oil gels Cera Beilina ... 

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