A- acetaldehydes

To a solution of 0.50 g of (-)-3a,5a-dihydroxy-2p-[(3RS)-3-hydroxy-3-methyl-trans-octenyl]cyclopentane-la-acetic acid - lactone 3-benzoate in 15 ml of tetrahydrofuran at -78°C under nitrogen was added 10 ml of 10% diisobutylaluminum hydride in toluene. After a gas evolution was ceased, the reaction was quenched by addition of 10 ml of saturated aqueous ammonium chloride. The resulting mixture was stirred at room temperature, filtered through Celite, and extracted with ethyl acetate. Extract was evaporated to give 0.48 g of (-)-3a,5a-dihydroxy-2p-[3-(RS)-3-hydroxy-3-methyl-trans-octenyl]cyclopentane-l-a-acetaldehyde y-lactol 3-benzoate as an oil. 

Fig. 2. Pressure—time plots for acid-washed and KCl coated vessels [44]. (a) Acetaldehyde (b) propionaldehyde aldehyde and oxygen pressures, 208 torr temperature, 143 °C uncoated vessel. Inset acetaldehyde and oxygen pressures, 100 torr temperature, 126 C (c) KCl coated and (d) uncoated vessels.

Fig. 4. Variation of the gradient of the eqn. (VI) plots with initial aldehyde pressure at 62.5 °C [43]. (a) Acetaldehyde (b) propionaldehyde (abs. x,2) (c) iso-butyraldehyde.

Figure 7.13. Cross sections through the T, (n,jr ) and T, ( r, r ) triplet surfaces for the a cleavage of a) acetaldehyde, b) acrolein, and c) benzaldehyde, leading to the bent acyl radicals. In a) and b), the surface crossing that is avoided for nonplanar geometries determines the barrier height and the location of the transition state (by permission from Reinsch et al., 1988).

Figure 7.1.2. Chromatogram for the pyrolysate of fructose obtained by on-line Py-GC/MS. The peak assignments are the same as in Figure 7.1.1. Peak 21 is missing. In addition, the following peaks were identified 1 a acetaldehyde, 2a propanone, 5a 2,3-butandione, 7a 5-methyl-2(3H)-furanone, 12a furanmethanol, 16a methyl 2-furoate, 16b 2,5-dimethyl-4-hydroxy-3(2H)-furanone, 19a 1,3,5-benzenetriol.

In the single-stage process (Figure 2) a mixture of ethylene and oxygen is passed through an aqueous solution of copper chloride and palladium chloride placed in a towerlike reactor (a). Acetaldehyde is formed according to eq. (6). 

Figure 6. Effect of AgA SZ catalyst potential and work function on the rates of formation of ethylene oxide (A), acetaldehyde (B) and CO2 ( ) T = 260°C P=500 kPa, Pq2= 17.5 kPa ...

Figure 5.8. The GC/MS-positive ion chemical ionization mass spectra of (a) acetaldehyde, (b) diacetyl monooxime, (c) acetoin, and (d) o-chlorobenzaldehyde PFBOA derivatives. The analytical conditions are reported in Table 5.12. (Reprinted from Journal of Mass Spectrometry 40, Flamini et al., Monitoring of the principal carbonyl compounds involved in malolactic fermentation of wine by synthesis of 0-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine derivatives and solid-phase-micro-extraction positive-ion-chemical-ionization mass spectrometry analysis, p. 1560, Copyright 2005, with permission from John Wiley Sons, Ltd.)...

Processes of this sort have been classified under the general name of pyrogenic decomposition and may be differentiated into two types (1) those which take place under the action of heat alone, and (2) those which take place under the action of heat in the presence of a catalyst. Tn the former case the product of the reaction frequently consists of a very complex mixture, the character of which is determined by the temperature, pressure and time of contact.8 In the latter case, the course of the reaction may in certain instances be so controlled as to favor the formation of a single product. The procedure may be varied by passing the vapor of the substance through a tube or chamber the walls of which arc themselves inactive but into which an appropriate catalyst has been introduced. This latter modification of the reaction has been made the. subject of careful investigation by Ipatiew, who was indeed the first to call attention to the definite quantitative differences in the amounts of (a) acetaldehyde and (b) ethylene which resulted from the pyrogenic decomposition of ethanol under the action of specific catalysts. 

Figure 3.1. Ultra-violet absorption spectra of (a) acetaldehyde and (b) methyl /-propyl ketone in different media I, gas phase II, heptane III, alcohol and IV, water...

The same principal products were detected in the photolysis of an alcohol and its corresponding ether. For example, ethanol and ethyl ether gave ethylene (process a), acetaldehyde (process b), and formaldehyde (process b). In an attempt to find out whether the formaldehyde and... 

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