Direct Preparation of Alcohols by Hydroformylation

Aldehydes and alcohols may resemble each other in their odor characteristics. However, in several cases (e.g., Cg-enals in relation to their corresponding alcohols) the odor strength of alcohols is 100-1000 times lower, which might be important for achieving certain odor impression [190]. 

Alcohols can be derived from aldehydes by hydrogenation or by a modified hydroformylation process, which gives directly the desired alcohol from the olefinic substrate (see Section 5.2). The linear and branched long-chain alcohols frequently obtained can be separated by dissolving the mixture in liquid hydrocarbons (butane, iso-pentane, -pentane) or methyl ferf-butyl ether (MTBE) and cooling to -20 to -52 C [191]. From the liquid, preferentially the linear alcohol recrystallizes. 

A herbaceous, strong green leafy, pepper and spicy aroma profile with herbaceous peppery olibanum and diffusive amber undertones 

With the assistance of an electron-rich bidentate ligand, one-pot hydroformylation-hydrogenation of -decene was possible in order to directly produce 1-undecanol [194]. In the reaction, almost double the H2 partial pressure was chosen in comparison to the partial pressure of CO. The formation of the desired alcohol could be improved further through reaction in an aqueous alcoholic solution and using Xantphos or P( -Bu)3 as ligands [195]. 

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