Methane carboxylation

Synonyms Acetasol Acetic acid (aqueous solution) AcOH AI3-02394 BRN 0506007 CCRIS 5952 EINECS 200-580-7 Ethanoic acid Ethylic acid FEMA No. 2006 Glacial acetic acid HAc Methane-carboxylic acid NSC 132593 Pyroligneous acid UN 2789 UN 2790 Vinegar acid Vosol. 

Synonyms Ethanoic acid ethylic acid methane carboxylic acid vinegar (4-6% solution in water)... 

Synonyms Acid methane carboxylic, Ethanoic acid, Purified pyroligneous acid, Vinegar. Appearance Clear, colorless liquid strong pungent odor. 

E260 ethanoic acid ethylic acid methane carboxylic acid vinegar acid. 

METHANE CARBOXYLIC ACID (64-19-7) Vapor forms explosive mixture with air (above 103°F/39°C). Reacts violently with bases such as carbonates and hydroxides, giving... 

SYNONYMS ethanoic acid, methane carboxylic acid, vinegar acid... 

Table VIII.2. Methane carboxylation promoted by lanthanoid compounds ...

Although sulfur- and phosphorus-containing betaine derivatives are effective as amphoteric surfactants, only the carboxybetaines are widely used. They are internal salts. [Betaine is trimethylammonium acetate, (CH3)3N CH2COO"]. The most frequently encountered example is (alkyldimethylammonio)methane carboxylate (DAMC). These... 

A comparison of the electron impact (El) and chemical ionization (Cl-methane) mass spectra of 1//-azepine-1-carboxylates and l-(arylsulfonyl)-l//-azepines reveals that in the El spectra at low temperature the azepines retain their 8 -electron ring structure prior to fragmentation, whereas the Cl spectra are complicated by high temperature thermal decompositions.90 It has been concluded that Cl mass spectrometry is not an efficient technique for studying azepines, and that there is no apparent correlation between the thermal and photo-induced rearrangements of 1//-azepines and their mass spectral behavior. 

The photo-Kolbe reaction is the decarboxylation of carboxylic acids at tow voltage under irradiation at semiconductor anodes (TiO ), that are partially doped with metals, e.g. platinum [343, 344]. On semiconductor powders the dominant product is a hydrocarbon by substitution of the carboxylate group for hydrogen (Eq. 41), whereas on an n-TiOj single crystal in the oxidation of acetic acid the formation of ethane besides methane could be observed [345, 346]. Dependent on the kind of semiconductor, the adsorbed metal, and the pH of the solution the extent of alkyl coupling versus reduction to the hydrocarbon can be controlled to some extent [346]. The intermediacy of alkyl radicals has been demonstrated by ESR-spectroscopy [347], that of the alkyl anion by deuterium incorporation [344]. With vicinal diacids the mono- or bisdecarboxylation can be controlled by the light flux [348]. Adipic acid yielded butane [349] with levulinic acid the products of decarboxylation, methyl ethyl-... 

Figure 15. Disproved isokinetic relationship for the proton transfer from nitro-methane to various carboxylic acid anions (156). Symbols as in Figure 13.

Phenol is carboxylated by a defined obligate syntrophic consortinm to benzoate, which is then degraded to acetate, methane, and CO2 (Knoll and Winter 1989). 

An extremely pure product results, when difluorochloro methane or difluoro-dichloro methane are used as solvents (79). Dichlorophosphoric acid is a fluid, colourless, very hygroscopic liquid, which is easily soluble in CHCI3, CCI4, Ethanol and Ether (6). In the liquid phase it is stable for some time at room temperature, whereas at 12 Torr there is no sign of decomposition up to 250 °C (6). According to the Raman spectra in the liquid it is dimeric in analogy to the carboxylic acids (20) ... 

Fig. 4. Proposed catalytic cycle for the hydroxylation of methane by MMO. The reductase and B components may interact with the hydroxylase in one or more steps of the cycle. Protons are shown in the step in which intermediate Q is generated, but other possibilities exist (see Fig. 3 and the text). The curved line represents a bridging glutamate carboxylate ligand.

Metalloenzymes with non-heme di-iron centers in which the two irons are bridged by an oxide (or a hydroxide) and carboxylate ligands (glutamate or aspartate) constitute an important class of enzymes. Two of these enzymes, methane monooxygenase (MMO) and ribonucleotide reductase (RNR) have very similar di-iron active sites, located in the subunits MMOH and R2 respectively. Despite their structural similarity, these metal centers catalyze very different chemical reactions. We have studied the enzymatic mechanisms of these enzymes to understand what determines their catalytic activity [24, 25, 39-41]. 

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