Acetophenone, selective hydrogenation

Acetophenone can be selectively hydrogenated to several products, depending on the ability of the catalyst to hydrogenate the aromatic ring or the carbonyl moiety... 

This section presents results from the selective hydrogenation of acetophenone and benzophenone. In the two cases studied, Pt-based (1 wt% Pt) and tin-modified Pt catalysts with a Sn/Pt = 1 ratio were used. These catalysts are solids that have the characteristics given in Table 6.9. 

Figure 6.16 Hydrogenation of acetophenone. Selectivity measured at 60% conversion in three hydrogenation cycles (a) Pt/SiOj (1 = PE, 2 = CHMK, 3 = CHE) (b) PtSn-BM ...

SELECTIVE HYDROGENATION OF ACETOPHENONE ON UNPHOMOTlO RANEY NICKEL INFLUtNCE OF THE REACTION CONDITIONS... 

In the presence of molten SbCls, anthracene and naphthacene are selectively hydrogenated by tetralin to give 9,10-dihydroanthracene and 5,12-dihydronaphtha-cene, respectively [31]. Both SbCls-Al and SbCls-Zn binary systems reduce a variety of aldehydes to the corresponding primary alcohols in DMF-H2O (Scheme 14.10) [32]. In the presence of a catalytic amount of SbCl3, acetophenones are reduced to 1-arylethanols by an electrochemical method [33]. Nitroarenes are reduced by Sb-NaBH4 in MeOH [34], and by Sb(.l, -Nal H4 in EtOH [35] to afford N-arylhydroxylamines (Scheme 14.11) and anilines (Scheme 14.12), respectively. 

Surface Organometallic Chemistry on Metals Selective Hydrogenation of Acetophenone on Modified Rhodium Catalyst. 

Kinetic investigation of the Pd/carbon-(S)-proline system in reduction of isophorone and acetophenone and comparison with known enantioselective hydrogenations were carried out. An addition reaction of (S)-proline with the substrates, and the selective hydrogenation of this adduct results in the optically active products, the kinetic analysis verified this mode of action these are rather diastereoselective reactions. 

Acetophenone is separated for hydrogenation to 1-phenylethanol, which is sent to the dehydrator to produce styrene. Hydrogenation is done over a fixed-bed copper-containing catalyst at 115—120°C and pressure of 8100 kPa (80 atm), a 3 1 hydrogen-to-acetophenone ratio, and using a solvent such as ethylbenzene, to give 95% conversion of the acetophenone and 95% selectivity to 1-phenylethanol (186,187). 

Another recent patent (22) and related patent application (31) cover incorporation and use of many active metals into Si-TUD-1. Some active materials were incorporated simultaneously (e.g., NiW, NiMo, and Ga/Zn/Sn). The various catalysts have been used for many organic reactions [TUD-1 variants are shown in brackets] Alkylation of naphthalene with 1-hexadecene [Al-Si] Friedel-Crafts benzylation of benzene [Fe-Si, Ga-Si, Sn-Si and Ti-Si, see apphcation 2 above] oligomerization of 1-decene [Al-Si] selective oxidation of ethylbenzene to acetophenone [Cr-Si, Mo-Si] and selective oxidation of cyclohexanol to cyclohexanone [Mo-Si], A dehydrogenation process (32) has been described using an immobilized pincer catalyst on a TUD-1 substrate. Previously these catalysts were homogeneous, which often caused problems in separation and recycle. Several other reactions were described, including acylation, hydrogenation, and ammoxidation. 

A competition between stoichiometric hydrogenation of acetone and acetophenone resulted in hydrogenation of the acetone [42]. Competitions of this type could be influenced by both the basicity of the ketone, as well as by the kinetics of hydride transfer to the protonated ketone. An intramolecular competition between an aliphatic and aromatic ketone resulted in preferential hydrogenation of the aliphatic ketone, with the product shown in Eq. (24) being isolated and fully characterized by spectroscopy and crystallography. Selective ionic hydrogenation of an aldehyde over a ketone was also found with HOTf and [Cp(CO)3WH],... 

The dimer of chloro(l,5-hexadiene)rhodium is an excellent catalyst for the room temperature hydrogenation of aromatic hydrocarbons at atmospheric pressure. The reaction is selective for the arene ring in the presence of ester, amide, ether and ketone functionalities (except acetophenone). The most useful phase transfer agents are tetrabutylammonium hydrogen sulfate and cetyltrimethylammonium bromide. The aqueous phase is a buffer of pH 7.6 (the constituents of the buffer are not critical). In all but one case the reaction is stereospecific giving cis products... 

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