Hydrogen HCOOH

Costain C C and Srivastava G P 1961 Study of hydrogen bonding miorowave speotra of CF3COOH-HCOOH J. Chem. Phys. 35 1903-4... 

Glycohc acid also undergoes reduction or hydrogenation with certain metals to form acetic acid, and oxidation by hydrogen peroxide ia the presence of ferrous salts to form glyoxylic acid [298-12A], HCOCOOH, and ia the presence of ferric salts ia neutral solution to form oxaHc acid, HOOCCOOH formic acid, HCOOH and Hberate CO2 and H2O. These reduction and oxidation reactions are not commercially significant. 

Another oxidation product can be obtained from the reaction of an acidic aqueous solution of potassium permanganate with methanol. The product has the formula HCOOH, and is called formic acid. The structural formula of formic acid is shown in Figure 18-7. The structure of formic acid is also related to the structure of formaldehyde. If one of the hydrogen atoms of formaldehyde is replaced by an OH group, the... 

The hydride phase may be present in a catalyst as a result of the method of its preparation (e.g. hydrogen pretreatment), or it may be formed during the course of a given reaction, when a metal catalyst is absorbing hydrogen (substrate—e.g. in H atom recombination product—e.g. in HCOOH decomposition). The spontaneous in situ transformation of a metal catalyst (at least in its superficial layer) into a hydride phase is to be expected particularly when the thermodynamic conditions are favorable. 

In the majority of the known examples, the donor of hydrogen equivalents is isopropanol HCOO" or HCOOH/EtjN azeotrope are less successful. Aromatic ketones (mainly acetophenone and benzophenone) were the easiest to reduce even under mild conditions and low catalyst loadings. 

Gdowski GE, Farr JA, Madix RJ. 1983. Reactive scattering of small molecules from platinum crystal surfaces D2CO, CH3OH, HCOOH and the nonanomalous kinetics of hydrogen atom recombination. Surf Sci 127 541. 

Ans. The electrons in the OH bond are attracted away from the hydrogen atom more by the Cl atom in CICOOH than by the H atom in HCOOH, since Cl is more electronegative than H. The H atom on the O atom in CICOOH is therefore easier to remove that is, it is more acidic. 

Thermal degradation of these amino acids yield such end products as hydrogen sulfide (H2S), ammonia (NH3), and methane (CH4), and organic acids such as acetic acid (CH3COOH) and formic acid (HCOOH). 

Unfortunately, the noise on the m/e = 2 signal was too high to allow accurate detection of molecular hydrogen in order to prove the existence of reaction (3.41). However, the existence of this process was supported by DEMS results on the same system at open circuit where HCOOH was one of the two major products along with H2CO. 

The results of these studies are tabulated in Table IV. This table lists the surfaces studied, the intermediates observed, the products, the adsorption temperature (T ds). the initial sticking probability of HCOOH (Sq), the peak temperature for product evolution (7J,), and the activation energy (E i) and the preexponential factor (v) determined by methods discussed earlier (see Section I,D). Data for HCOOD is given where available in order to distinguish the two hydrogens in the acid. 

A robust and highly active catalyst for water-phase, acid-catalyzed THs of carbonyl compounds at pH 2.0-3.0 at 70 °C was disclosed by Ogo and coworkers [60]. The water-soluble hydride complex [Cp lr(bipy)H] (72, Cp = Tl -CsMes, bipy = 2,2 -bipyridine) was synthesized from the reaction of [Cp lr(bipy)(H20)] (73) with HCOOX (X = H or Na) in H2O under controlled pH conditions (2.0 < pH < 6.0, 25 °C). The pH control is pivotal in avoiding protonation of the hydrido ligand of 72 below pH ca. 1.0 and deprotonation of the aquo ligand of 73 above pH ca. 6.0. The rate of the reaction is heavily dependent on the pH of the solution, the reaction temperature, and the concentration of HCOOH. High TOFs of the acid-catalyzed transfer hydrogenations at pH 2.0-3.0, ranging from 150 to 525 h, were observed for a variety of linear and cyclic ketones, as summarized in Table 4.5. 

Table 4.5 Transfer hydrogenation of various ketones in water, catalyzed by 73 using HCOOH at pH 2.0.

A series of chiral N,S-chelates was synthesized as ligands for the iridium(l)-catalyzed reduction of ketones using either HCOOH/NEtj or isopropanol as hydrogen sources. The ligands were obtained by sulfoxidation of an (R)-cysteine-based aminosulfide, providing a diastereomeric ligand family containing a chiral sulfur... 

Figure 1.18 The three high-field signals, C1-C3, in the C h, H NMR spectrum of the product obtained by transfer hydrogenation of PhCH=C(COOH) —CH2COOH with HCOOH/NEt3, a1 about 25% conversion. The chemical shifts for the undeuterated isotopomer 90a are d Cl 44.3, i5 C2 38.6 and d C3 35.9, respectively.

While treatment with aqueous sulfuric acid hydrolyzes hydrogen cyanide to formic acid, HCOOH, its reaction with concentrated sulfuric acid is violent forming an adduct HCN H2S04. The adduct is unstable, decomposing to carbon dioxide, sulfur dioxide and ammonia ... 

Other model reactants are simple organic molecules, for example, formic acid [381, 382]. Pt(lll) exerts lower catalytic influence on HCOOH oxidation than do Pt(lOO) and Pt(llO) faces. However, in the presence of Pb adatoms on Pt(lll) a strong catalytic influence has been observed [383]. The poisonous species production in HCOOH oxidation is then inhibited. Electrochemical reduction of CO2 to glycolate/glyoxylate and oxalic acid has been studied [384]. Other products such as formic acid accompanied by CO and methane have also been detected [385]. In the latter case, the efficiency of the competing process of hydrogen evolution has been suppressed to less than 3.5%. 

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