CAC - Large Scale Continuous Use

Ligands

Substrates

Solvents

Anchored
Precursors

Large Scale
Continuous Use

Most of the reactions discussed in the other sections have used rather small amounts of substrate in order to acquire a good amount of reaction data in a reasonable length of time. For the most part, these reactions used substrate/catalyst ratios of 50 to 100. Since these low ratios are not indicative of any potential commercial use of these catalysts, several anchored homogeneous catalysts have been used in either larger scale multiple batch reactions or in a continuous reaction using a Continuous Stirred Tank Reactor (CSTR).

One of the large scale reactions was the hydrogenation of 5 mL portions of 1-hexene over an anchored Rh(dppb) catalyst prepared by treating the anchored precursor with the dppb ligand. The overall S/C ratio was about 10,000. Analysis of the reaction mixture showed that Rh was present in less than 1ppm. Another example of a large scale multiple batch reaction was the use of an anchored Rh(Me-DuPhos) to hydrogenate 10mL portions of DMIT. Only 5mL of the solvent EtOH was used. The amount of Rh(Me-DuPhos) used was 28 moles while the total amount of DMIT was 0.28 mmoles giving a S/C ratio of 10,000. The TOF for the reaction was 11 mmoles H2 / mmole Rh / min. and the product ee was 97% - 98%.

Figure 1

Fig. 1 shows the comparison between the hydrogen uptake curves between a single batch reaction in which the S/C ratio was about 3,500 and the use of CSTR for the same reaction, again with a S/C ratio of about 3,000. The reaction was the hydrogenation of DMIT over anchored Rh(Me-DuPhos) run at R.T. and 100 psig. The product ee's were 90% in both reactions and the amount of Rh in the product mixtures was less than 2.5 ppm.

Figure 2

Fig. 2 Shows a more detailed analysis of a continuous DMIT hydrogenation over anchored Rh(Me-DuPhos) at R.T. and 50 psig. The slight break in the data curve at about 120 hours was the result of a change in the DMIT. The original material was used up and replaced by some obtained from another source. No color was seen in the reaction mixture at any time indicating that little if any complex was leached from the catalyst.



	400 South Orange Ave South Orange, NJ 07079 United States

	Contact CAC
	Robert L. Augustine
	Setrak K. Tanielyan