Low pressure rhodium catalyzed hydroformylation of olefins

A method for the hydroformylation an unsaturated compound to produce an aldehyde, wherein said unsaturated compound is selected from the group consisting of:

• C.sub.2 up to C.sub.20 mono olefins,
• non conjugated polyolefins, and substituted derivatives thereof, wherein the substituted derivatives contain one or more of the substituents selected from the group consisting of:
• OH,
• OR";
• wherein R" is a C.sub.1 up to C.sub.20 alkyl, aryl, alkaryl or aralkyl radical, ##STR13## wherein R'" is a C.sub.1 up to C.sub.20 alkyl, aryl, alkaryl or arakyl radical, ##STR14## wherein R' is independently selected. from H, C.sub.1 up to C.sub.12 alkyl radicals or substituted alkyl radicals, and C.sub.6 up to C.sub.12 aryl radical or substituted aryl radicals, and each R.sup.iv is independently selected from the members defined by R', where the R.sup.iv groups can be joined together to form a cyclic acetal or ketal,
• SR";
• wherein R" is as defined above, and ##STR15## wherein R'" is as defined above;
• said method comprising contacting at least one of said olefins with a mixture of hydrogen and carbon monoxide in a molar ratio falling in the range of 0.1:1 up to 20:1, and a catalyst comprising rhodium in chemical complex with at least one bidentate ligand having the structure:
• ##STR16## wherein Ar is selected from aromatic ring compounds having 6 up to 14 carbon atoms;
• the x bonds and the y bonds are attached to adjacent carbon atoms on the ring structure;
• each R, when present as a substituent, is independently selected from alkyl, alkoxy, aryloxy, aryl, aralkyl, alkaryl, alkoxyalkyl, cycloaliphatic, halogen, exclusive of (except Cl, Br or I on the aromatic nucleus on the carbon atom adjacent to the carbon atoms bearing the x or y bonds, alkanoyl, alkanoyloxy, alkoxycarbonyl, formyl, carboxylate moieties, sulfonic acid derivatives, or amino moieties;
• n is a whole number in the range of 0-4 where Ar is phenyl;
• 0-6 where Ar is naphthyl;
• and 0-8 where Ar is phenanthryl or anthracenyl;
• each R.sub.1 and R.sub.2 is independently selected from alkyl, aryl, aralkyl alkaryl, cycloaliphatic radicals and substituted derivatives thereof;
• each R.sub.3 and R.sub.4 is independently selected from hydrogen and the R.sub.1 substituents;
• each of the above alkyl groups or moieties is straight or branched chain of 1-20 carbons;
• each aryl group contains 6-10 ring carbons;
• each cycloaliphatic group contains from 4-8 ring carbons;
• and
• each Y is independently selected from the elements P, As, Sb and Bi;
• said contacting being carried out in a reaction zone at a temperature in the range of about 20.degree. up to 250.degree. C. and a pressure in the range of about 15 up to 800 psig for a time sufficient for said olefin to react with said synthesis gas to form aldehyde product.