Oxygen, compounds containing

Aliphatic carbonyl compounds, such as diacetyl, which has a butter-like odour, also may contribute to the aromas derived from the MaiUard reaction, and many of the Strecker aldehydes also have characteristic aromas (Table 12.1). 

Amino acid Strecker aldehyde Odom description 

Leucine 3-Methylbutanal Malty, fruity, toasted bread 

Methionine Methional, methane-thiol, 2-propenal Vegetable-hke aromas 

Proline Pyrrolidine, 1-pyrroline. No Strecker aldehyde Important intermediates for bread-like aromas 

Oxygen containing compounds are important industrially where they are used as solvents and feedstocks for catalytic processes ( 7.4.3). The interaction of methanol, ethanol, 1-propanol and 1-butanol with zeolites was studied [52]. The spectra of the solid alcohols are shown in Fig. 8.9. Alcohols readily form glasses and the lack of spectral detail in the external mode region of ethanol, propanol and butanol suggests that this has occurred in their spectra. DFT calculations of the spectra of dimers and trimers of the molecules gave reasonable agreement with the spectra. 

The simplest aromatic alcohol, phenol, has not been investigated by INS although the chloro derivative pentachlorophenol [53] has been studied. The molecule forms a number of unusually strongly hydrogen bonded complexes with substituted pyridines and this is undoubtedly the first step in the investigation of these complexes. 

Aldehydes, ketones and ethers have yet to be studied by INS spectroscopy. Formic acid, has been extensively investigated [54-56]. The low temperature phase consists of chains of hydrogen bonded molecules. Fig. 8.10 shows the power of selective deuteration to provide unequivocal assignments for the modes, which are given in Table 8.2. 

Sodium and potassium formate, together with copper formate (anhydrous and as the tetrahydrate) have been used as model compounds for surface formates [56] and 7.4.3. Copper formate tetrahydrate undergoes an antiferroelectric transition at 235.5 K. The INS spectra clearly show that above this temperature the water molecules are disordered and below it they are ordered [57]. 

Potassium oxalate monohydrate [58] forms chains of alternating oxalate and water moieties. INS of single crystals has been used to assign the water translational and librational modes. Fig. 9.5. 

Aliphatic Carboxylic Acids. Nagy and Bitz (1963) reported fatty acids from to Cjg in Orgueil. This work was substantially confirmed by Hayatsu (1965) and Smith and Kaplan (1970). The latter authors found 3 to 91 ppm fatty acids from Cj to Cjo in 7 carbonaceous chondrites. Smith and Kaplan believe that these acids are largely or entirely terrestrial contaminants, because unstable, unsaturated acids comprise about 30% of the total, and Cjg and Cjg acids are predominant. The case 

Extending this work. Lawless and Yuen (1979) made a quantitative study of monocarboxylic acids in Murchison. Eleven acids, ranging from to Cg, were identified. Of these, propanoic acid was the most abundant (1.83 pmol/g), exceeding the concentration of the most abundant amino acid, glycine, by a factor of 58. 

The Miller-Urey reaction fails qualitatively rather than quantitatively. It produces no detectable normal acids above Cg, even in the presence of an alkaline aqueous phase that is known to favor growth of linear chains by formation of a monolayer (Allen and Ponnamperuma, 1967). Given the fundamentally random nature of the Miller-Urey reaction, there is little hope that it will ever achieve the needed selectivity for normal isomers. 

Seven a-hydroxycarboxylic acids (Cj to Cj) and 17 aliphatic dicarboxylic acids (Cj to Cg) have been found in Murchison (Peltzer et al, 1978 Lawless et al, 1974). Eight of the latter also were produced in a Miller-Urey synthesis (Zeitman et al, 1974). None have been looked for in the FTT synthesis thus far. 

Synthesis. - Cycloadditions. A bis-heteroannelation approach to ( )-ligularone (90) from (89) has been reported. Other intramolecular cycloadditions include the conversions of (91) into (92) and the intramolecular addition to the benzyne (93), which is the key to the synthesis of ( )-mansonone (94).  

This section is dominated by cycloadditions involving furans and isobenzo-furans. The new dienophile ethyl (diethoxyphosphinyl)propynoate is highly 

Hagenburgh, P. Vogel, A. A. Pinkerton, and D. Schwarzenbach, Helv. Chim. Acta, 1981,64, 1818. 

Cycloaddition of diphenylisobenzofurans to (101), to sulphenes, to 2-phenyl-3-spirocyclopropylazirines, and to o-benzoquinonedi-imines have been reported. The preparation and trapping of 1-methoxy- and 1-benzyl-isobenzofuran have been described and a high degree of regio-and stereo-specificity is observed in the reactions of a range of 1-substituted isobenzofurans with quinone acetals, for example in the formation of 

As an example, 4-methyl-5-propyl oxazole has been characterized as having a green vegetable aroma. However, oxazoles which have a 4 or 5 carbon length chain on the oxazole ring and no alkyl group on carbon-2 or 4 have distinct bacon-fatty notes (e.g., 5-butyl oxazole). When a methyl or ethyl group is substituted on carbon-2 (e.g., 2-ethyl-5-butyl oxazole), the fatty aroma is reduced and sweet-floral aromas become more characteristic. The sweet-floral character is further enhanced by additional methyl or ethyl substitution on carbon-4 [69]. The oxazolines tend to have a wide variety of sensory properties. 2-isopropyl-4,5,5-trimethyl-3-oxazoline has a rum-like note while 2-isopropyl-4,5-diethyl-3-oxazoline has a typical cocoa aroma. 

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Solvation increases solubility above predicted values. When the components of a solution possess an abnormally large attraction for each other, solvates are formed. Thus certain oxygen-containing compounds have a great tendency to form hydrates, thus contributing to increased water solubility hydrogen bondir also plays an important role. 

Concentrated sulphuric acid. The paraffin hydrocarbons, cych-paraffins, the less readily sulphonated aromatic hydrocarbons (benzene, toluene, xylenes, etc.) and their halogen derivatives, and the diaryl ethers are generally insoluble in cold concentrated sulphuric acid. Unsaturated hydrocarbons, certain polyalkylated aromatic hydrocarbons (such as mesitylene) and most oxygen-containing compounds are soluble in the cold acid. 

Many oxygen-containing compounds dissolve because of the formation of oxonium salts the latter are readily decomposed (hydrolysed) by pouring the acid into ice water. 

The production of both an alcohol and the sodium salt of an acid might easily be confused with the hydrolysis products of an ester (in the above instance benzyl benzoate). Such an error would soon be discovered (e.g., by reference to the b.p. and other physical properties), but it would lead to an unnecessary expenditure of time and energy. The above example, however, emphasises the importance of conducting the class reactions of neutral oxygen-containing compounds in the proper order, viz., (1) aldehydes and ketones, (2) esters and anhydrides, (3) alcohols, and (4) ethers. 

If the unknown neutral, oxygen-containing compound does not give the class reactions for aldehydes, ketones, esters and anhydrides, it is probably... 

Neutral oxygen-containing compounds in Solubility Groups I, II and V which either contain the CHjCO— group attached to H, alkyl, aryl, or ester H R... 

Salts are formed as with oxygen-containing compounds. For example, C2H5 — S—Na is named either sodium ethanethiolate or sodium ethyl sulfide. If mercapto- has been used as a prefix, the salt is named by use of the prefix sulfido- for —S . 

Table 4. Boron Trifluoride Adducts with Oxygen-Containing Compounds...

At high temperatures, aluminum reduces many oxygen-containing compounds, particularly metal oxides. These reactions, of the type shown in equation 6, are used in the manufacture of certain metals and alloys, as well as in the thermite welding process. ... 

Final Purification. Oxygen containing compounds (CO, CO2, H2O) poison the ammonia synthesis catalyst and must be effectively removed or converted to inert species before entering the synthesis loop. Additionally, the presence of carbon dioxide in the synthesis gas can lead to the formation of ammonium carbamate, which can cause fouHng and stress-corrosion cracking in the compressor. Most plants use methanation to convert carbon oxides to methane. Cryogenic processes that are suitable for purification of synthesis gas have also been developed. 

Typical isobutylene, as suppHed to the butyl mbber process, has a purity in the range of 95—99%, and includes varying amounts of propene, 1-butene, 2-butene, isobutylene dimer, and tert-huty alcohol, and trace quantities of a variety of oxygen-containing compounds, depending on the process employed. 

Oxidation of Hydrocarbons. Ethanol is one of a variety of oxygen-containing compounds produced by the oxidation of hydrocarbons. Ethanol is reported to be obtained in a yield of 51% by the slow combustion of ethane (158,159). When propane is oxidi2ed at 350°C under a pressure of 17.2 MPa (170 atm) (160,161), 8% of the oxygen is converted to ethanol. Lower conversions to ethanol are obtained by oxidi2ing butane. Other oxidation systems used to produce ethanol and acetaldehyde (162—164) and methods for separating the products have been described in the patent Hterature. 

The Diels-Alder reaction of nitroalkenes with Danishefsky s dienes is applied to synthesis of truncated carbocyclic analogues of a potent neuraminidase inhibitor 4-guanidino-NemAc en fsee Scheme 8.5. Carbocyclic analogs are found to retain interesting levels of antiviral activity comparable to those shovm by their oxygen-containing compounds in Scheme 8.5. 

Note. The addition of a chlorohydrocarbon vapour to the carrier gas is found to enhance the decomposition of the oxygen-containing compounds. 

Of the many tests which have been submitted, the determination of active oxygen or peroxide content seems to give rather good correlation of data. During the oxidation of fat, certain oxygen-containing compounds are formed which are active in the sense that they are capable of liberating iodine from potassium iodide (19). The liberated iodine may be determined quantitatively and it thus becomes a measure of rancidity. 

The peak representing the loss of water from the molecular ion can easily be mistaken for the molecular ion. The spectrum is similar to an olefin below the [M - H20]+ peak except that the peaks at m/z 31, 45, and 59 indicate an oxygen-containing compound. 

Catalysis by metalloporphyrins of reactions involving oxidation by molecular oxygen and oxygen-containing compounds. N. S. Enikolopyan, K. A. Bogdanova, L. V. Karmilova and K. A. Askarov, Russ. Chem. Rev. (Engl. Transl.), 1985,54,215 (188). 

Ozone forms in the stratosphere in two steps. First, 02 molecules or other oxygen-containing compounds are broken apart into atoms by sunlight, a process called photodissociation ... 

The bonding pattern of the oxygen atoms in acetic acid repeats in most other oxygen-containing compounds. Outer oxygen atoms frequently have some n character in their bonding. Inner oxygen atoms, on the other hand, do not... 

To illustrate the first remark, no reported accident has ever involved an oxygen-containing compound of zirconium with a high oxidation state. 

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