Bond distances acetic acid

Bond distances acetic acid, 742 acetylene, 341—342, 343 alkyl hahdes, 129 allene, 377... 

Likewise the experimentally measured pattern of carbon-oxygen bond lengths m acetic acid is different from that of acetate ion Acetic acid has a short C=0 and a long C—O distance In ammonium acetate though both carbon-oxygen distances are equal... 

One after the other, examine methanol dimer and acetic acid dimer. Do the hydrogen-bond lengths in these systems differ significantly from the optimum distance in water dimer Are the hydrogen-bond angles in these compounds significantly different from those in water dimer Rationalize your results. 

For acetic acid, CH3COOH, in which the bond from carbon to the OH group has about 35 per cent double-bond character and that to the oxygen atom about 65 per cent double-bond character, as determined from the interatomic distances, we would predict for the potential hump a value about one-third that in acetaldehyde. This prediction is borne out by experiment, the height of the barrier being 0.48 kcal/mole. 

Mercaptophenylacetic acid, acetic anhydride, and sodium nitrite yielded the first example (169, R = Ph) of a meso-ionic 1,3,2-oxathiazol-5-one this compound has a dipole moment of 4.5 D. An X-ray crystallographic investigation of the 4-phenyl-l,3,2-oxathiazol-5-one (169, R = Ph) has been reported. This compound is incorrectly described as a thiosydnone. The bond distances support the structure with tetracovalent sulfur, and on this evidence alone the compound 169, R = Ph, could be judged not to be meso-ionic because it can, on the basis of the X-ray evidence, be more satisfactorily represented by a covalent formulation. 

The value 2.70 A for the O—H- O distance in this substance is smaller than that in ice, 2.76 A, as expected for this stronger bond. From the enthalpy of dimerization, 14.12 kcal/mole, the O—H O bond energy is found to have the value 7.06 kcal/mole. The value 7.6 kcal/mole is similarly found for the hydrogen-bond energy in acetic acid. 4 These values are about 50 percent greater than those for ice. 

The distance from each hydrogen atom to the nearer of the two adjacent oxygen atoms in the dimer of acetic acid has been reported to be 1.075 0.015 A this is considerably greater than the value 1.01 A for ice, as is to be expected in consequence of the increased strength of the hydrogen bond. 

Acetic acid by itself acts as a monodentate neutral ligand in the hexakis complex [Ni(HOCOMe)6](BF4)2.1718,1748 The Ni—O bond distances are similar to those observed in the acetate complex indicating that MeC02H is as strong a donor as its conjugate base. The hexakis acetic add complex dissolves in MeN02 without appredable dissociation. 

The rapid fall in the reactivity of a CH bond, as its distance from the substituent X increases, indicates the importance of the inductive effect in hydrogen exchange with a base. This conclusion is reinforced by the fact that there is a linear relation (Fig. 3) between of and pKt for substituted acetic acids (CH2X.COOH) with the same substituent X... 

Figure 21.2 Four optimized candidates of acetic acid water dimer, denoted as lAlW-n, 1A and 1W stand for one acetic acid and one water, respectively, n from 1 to 4 denotes for different structures. The distance O H of hydrogen bond is shown on its side. The total energy (in HartreeJ/interaction energy (in kj mol-1) is listed below the corresponding candidate.

Figure 21.5 Selected and optimized structures of acetic acid di-, tri-, and tetra-hydrate are denoted as lAmW-n. 1A stands for the one acetic acid molecule, W for water, m for the number of water molecules, and n from 1 to 4 or 5 for different structures. The hydrogen bond is represented as the dashed line, the distance of the hydrogen bond O H is given on its side. The total energy/interaction energy below each corresponding structure is given in Hartree/kJ mol-1.

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