Asymmetric hydrogenation on metal-quartz catalysts

The asymmetric adsorption of some organic and complex compounds on quartz crystals was described in Chapter 1.2. In 1932 Schwab and cowoikers were first to show that chiral quartz crystals can be used as chiral supports for metal catalysts Seven years later Stankiewicz, in his dissertation 

400-500°C and atmospheric pressure with catalysts composed of Cu, Ni, or Pt deposited in thin layers on d- or /-quartz. 

At high reaction temperatures (400-500°C) the rate of racemization of the optically active butan-2-ol becomes fast enough that the optical rotation of the product goes through a maximum as a function of reaction time. Results received with a 0.10% Ni-t/-quartz catalyst at 550-560°C are shown below in Table 2.1. 

In 1938 Stankiewicz reproduced the asymmetric 2-butanol decomposition experiments of Schwab (1932) at a higher temperature and atmospheric pressure and extended studies to the asymmetric decomposition of racemic menthol and 3-methylheptan-3-ol. Over a Cu-r/-quartz catalyst the latter substrate produced a maximal optical rotation of -0.26° and the decomposition of 2-butanol gave a reaction mixture with a rotation of +0.25°. 

1) by high vacuiun cathodic scattering of Pt on quartz powder with periodic shaking to obtain imiform layers 

---