Letter: Silver Mediated Ester Bond Formation in the Gas Phase: Substrate Structure is Important

2007 ◽  
Vol 13 (5) ◽  
pp. 367-372 ◽  
Author(s):  
George N. Khairallah ◽  
Tom Waters ◽  
Richard A.J. O'Hair
Keyword(s):  
Gas Phase ◽  
Bond Formation ◽  
Adduct Formation ◽  
Ester Bond ◽  
Silver Acetate ◽  
Allyl Acetate ◽  
Substrate Structure ◽  
Allyl Iodide ◽  
Multiple Interactions ◽  
Silver Atoms

The silver acetate cation CH3CO2Ag2+ reacted with allyl iodide via C–O bond coupling to produce Ag2I+ and allyl acetate, but only underwent adduct formation with methyl iodide, highlighting the importance of substrate on reactivity. DFT calculations predicted the reaction with allyl iodide to be exothermic by 0.48 eV and suggested that intermediates in the reaction benefit from multiple interactions between the allyl and iodide moieties of allyl iodide and the two silver atoms in CH3CO2Ag2+.

Synthesis of para-olivetol depsides

1974 ◽  
Vol 27 (8) ◽  
pp. 1767 ◽  
Author(s):  
JA Elix
Keyword(s):  
Bond Formation ◽  
Trifluoroacetic Anhydride ◽  
Ester Bond ◽  
Catalytic Hydrogenolysis

The unambiguous synthesis of the lichen depsides, anziaic, perlatolic, 2'-O-methylanziaic, 2-O- methylperlatolic, 2'-O-methylperlatolic, 4-O-demethylplanaic, planaic, imbricaric and stenosporic acids is reported. Where necessary the phenolic and carboxy groups of the intermediate phenols were protected by O-benzylation until after the depside-ester bond formation had been achieved by treatment with trifluoroacetic anhydride. Catalytic hydrogenolysis of the depside esters so formed subsequently gave the natural acids.

scholarly journals Decarboxylation versus Acetonitrile Loss in Silver Acetate and Silver Propiolate Complexes, [RCO2Ag2(CH3CN)n]+ (where R = CH3 and CH3C≡C; n = 1 and 2)

2015 ◽  
Vol 68 (9) ◽  
pp. 1385 ◽  
Author(s):  
Jiawei Li ◽  
George N. Khairallah ◽  
Richard A. J. O'Hair
Keyword(s):  
Dft Calculations ◽  
Gas Phase ◽  
Density Functional ◽  
Ion Trap ◽  
Fragmentation Pathway ◽  
Binding Energies ◽  
Silver Acetate ◽  
Bond Forming ◽  
Fragmentation Reactions ◽  
A Minor

Gas-phase experiments using collision-induced dissociation in an ion trap mass spectrometer have been used in combination with density functional theory (DFT) calculations (at the B3LYP/SDD6–31+G(d) level of theory) to examine the competition between decarboxylation and loss of a coordinated acetonitrile in the unimolecular fragmentation reactions of the silver acetate and silver propiolate complexes, [RCO2Ag2(CH3CN)n]+ (where R = CH3 and CH3C≡C; n = 1 and 2), introduced into the gas-phase via electrospray ionisation. When R = CH3, loss of acetonitrile is the sole reaction channel observed for both complexes (n = 1 and 2), consistent with DFT calculations, which highlight that the barriers for decarboxylation 2.18 eV (n = 2) and 1.96 eV (n = 1) are greater than the binding energies of the coordinated acetonitriles (1.60 eV for n = 2; 1.64 eV for n = 1). In contrast, when R = CH3C≡C, decarboxylation is the main fragmentation pathway observed for both complexes (n = 1 and 2), with loss of acetonitrile only being a minor product channel. This is consistent with DFT calculations, which reveal that the barriers for decarboxylation are 1.17 eV (n = 2) and 1.16 eV (n = 1), which are both below the binding energies of the coordinated acetonitriles (1.55 eV for n = 2; 1.56 eV for n = 1). The barrier for decarboxylation of [CH3C≡CCO2Ag2]+ is 1.22 eV, which is less than the 2.06 eV reported for decarboxylation of [CH3CO2Ag2]+ (Al Sharif et al. Organometallics, 2013, 32, 5416). The observed ease of decarboxylation of silver propiolate complexes in the gas-phase is consistent with the recently reported use of silver salts in metal catalysed decarboxylative C–C and C–X bond forming reactions of propiolic acids.

Thermodynamics of metal-ligand bond formation. XXV. Addition of bases to Bis[O,O'-diethyl thiomalonato]nickel(II) in various solvents

1977 ◽  
Vol 30 (3) ◽  
pp. 495 ◽  
Author(s):  
L Ang ◽  
DP Graddon ◽  
VAK Ng
Keyword(s):  
Thermodynamic Data ◽  
Driving Force ◽  
Bond Formation ◽  
Adduct Formation ◽  
Calorimetric Measurements ◽  
Carbon Tetra ◽  
Metal Ligand ◽  
Ligand Bond

Thermodynamic data have been obtained from spectroscopic and calorimetric measurements for the addition of pyridine and 4- methylpyridine to bis(O,O?-diethyl thiomalonato)nickel(II), Ni(etm)2, in solution in cyclohexane, benzene, 1,2-dichloroethane, acetonitrile, butan-2-one and carbon tetra-chloride. In each solvent two base molecules add successively, giving Ni(etm)2B then Ni(etm)2B2. There are only small variations in K1 and K2 in different solvents; typically K1 ≈ 200, K2 ≈ 100 l. mol-1, ΔH�1+2 ≈ -65, ΔH�2 ≈ 0 kJ mol-1 at 30�C, but in benzene and cyclohexane ΔH�2 ≈ -25 and in cyclohexane ΔH�1+2 ≈ -100 kJ mol-1. The main driving force for adduct formation is apparently the formation of the first Ni-N bond, which is accompanied by a spin change.

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