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The influence of zinc and its salts on the oxo process

V. Macho

Research Institute for Petrochemistry, Nov√°ky

 

Abstract: The reaction of MeCH:CH2 (I) with a mixt. (II) of equal vols. of CO and H to give butyraldehydes (III) by the oxo synthesis, catalyzed by Co2(CO)8 (IV) was inhibited by Zn or Zn stearate (V). The conversion of I (%) depended on the molar ratio (Zn:Co) as follows: 90 (0.5), 73(1.0), 9 (3.0). Attaining reaction equil. was retarded by Zn from 1.25 hrs. to 5.5 hrs. The expts. were run in a 0.5 l. stainless-steel rotating autoclave, contg. 25 g. of solvent (PhMe or a mixt. of hydrogenated Oxo products, b20 80-200°, d20 0.8575, n20D 1.437), 0.05 g. Co (as IV or Co stearate), a known amt. Zn (as powd. metal or V), and 25-6 g. I. The autoclave was charged with II up to 145 atm., heated up to 150°, and held at this temp. until there was no further pressure drop. It was suggested that inhibition was due to formation of the catalytically inactive Zn[Co(CO)4]2 (VI), the structure of which was discussed. At a const. wt. ratio (1.45) of Zn: Co, the thermal instability of VI was demonstrated by the following effect of temp. on conversion of I (%) and reaction time (hrs.): 140° (56.3, 4.0), 150° (57.3, 6.15), 170° (91.0, 4.75), and 184° (100, 3.30). A secondary formation of 2-ethyl-4-methylpent-2-enal (VII), and esp. 2-ethylhex-2-enal (VIII) from the primary product III under catalysis of Zn was demonstrated by a series of isochronic expts. In these, 50 g. I, 15 g. PhMe, 0.05 g. Co (as Co stearate), and a known amt. V were made to react at 150 ± 3° with excess II at the const. pressure of 200 ± 10 atm. for exctly 90 min. The results (wt. ratio Zn-Co, conversion of I in %, content of III in %, wt. ratio PrCHO-iso-PrCHO, content of VII in %, and content of VIII in %) were as follows: (no Zn) 94.5, 68.4, 1.446, 0.83, 2.5; 0.092, 85.1, 58.5, 1.49, 0.5, 2.41; 0.183, 78.0, 58.5, 1.26, 0.8, 3.18; 0.92, 71.1, 58.0, 1.02, 3.2, 13.9; and 1.464, 46.6, 53.9, 1.04, 2.4, 14.9. Under the above conditions, the presence of Zn afforded no advantage over the conventional oxo process.

Full paper in Portable Document Format: 178a525.pdf (in Slovak)

 

Chemical Papers 17 (8) 525–532 (1963)

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