Aldehydes propanal

The reaction of [Mn(salpn)H20] and [Mn(salpn)] (salpn = NA -disalicyl-aldehyde-propane-1,3-diamine) with oxygen has been studied under various... 

However for the formation of optically active a-alkyl aldehydes, the imine or hydrazone routes have proved of considerable value.122 In the preparative example123 the aldehydes propanal and octanal are converted with (S)-( — )-2-amino-l-methoxy-3-phenylpropane (14) into the imines (15) and (16) respectively. Treatment with lithium diisopropylamide then yields the corresponding lithioenamines [only the (fs)-isomers are formulated, since the (Z)-isomers would be less stable]. These intermediates have a topography which determines the subsequent direction of attack by the alkyl halide (see also Section 5.11.7, p. 688). In the formulation below, this stereoselection is from above the plane of the paper and leads to the (/ )- and (S)-2-methyloctanals respectively. 

Fig. 8.4 (a) shows the response of the oxygenate sensor-1 (Sn02 sensitized with Ti02) towards an alcohol (1-propanol), aldehyde (propanal), ketone (acetone), carbon monoxide (CO) and propane. The sensor is sensitive to the alcohol, aldehyde and ketone but not to CO and propane. Conversely, oxygenate sensor 2 (Sn02 sensitized with 13 wt% Si02/Al203) is less sensitive to the alcohol than aldehyde (Fig. 8.4b). Alcohol formation can thus be estimated from a comparison of the output signals of oxygenate sensors 1 and 2.

Similarly, aldehydes and ketones can have the same overall molecular formula but different structures. Each series contains a carbonyl group (C=0) but in each compound they are attached to different groups. The ketone has always got a C-CO-C chain, whereas the aldehyde has a CHO group which is always at the end of the molecule. The first member of the ketone series, propanone, is isomeric with the aldehyde propanal (Figure 6.4.11). 

The structure of aldehydes and ketones, (a) The general structure of an aldehyde and a ball-and-stick model of the aldehyde propanal. (b) The general structure of a ketone and a ball-and-stick model of the ketone propanone. 

Reaction I sequence results in the alcohol shown above (Compound A). The alcohol formed is oxidized by pyridinium dichromate. The product formed is an aldehyde (propanal). 

In this experiment, the addition of a nucleophflic Grignard reagent (1-methylbutyl-magnesium bromide), to the electrophilic carbonyl carbon of an aldehyde (propanal) is described. The product obtained is a 2° alcohol, 4-methyl-3-heptanol. Because it is possible to vary the structure of both the Grignard... 

In this case, the aldehyde, propanal, can be isolated in moderate yield because it is relatively volatile and can be removed from the reaction mixture by distillation as it is formed. If not removed, the aldehyde, which is in equilibrium with the corresponding hydrate (geminal diol), is oxidized further to the carboxylic acid ... 

The same group also investigated a self-Mannich reaction of aliphatic aldehyde (propanal) with p-anisidine under ultrasonic conditions (1 h) [54]. After subsequent reduction with sodium borohydride the corresponding aminoalcohol was obtained with good yield (80%) and selectivity (95 5 dr, 91% ee). In this case it is difficult to evaluate the effect of ultrasound because no comparative studies under conventional conditions were reported. 

The secondary alcohol can be made via a Grignard reaction between ethyl magnesium bromide and an aldehyde (propanal). 

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