NOVELTY - Minimizing production of at least one phosphonium ion ligand degradation product during reaction of a polyolefin compound involves conducting the reaction with a triorganophosphine ligand having a steric and/or electronic property; and/or conducting the reaction process under selected conditions of conversion temperature and/or pressure.    USE - Minimizing production of phosphonium ion ligand degradation products in a reaction process of polyunsaturated olefin or unconjugated functionalized olefin (claimed).    ADVANTAGE - The process is effective in minimizing the phosphonium ion ligand degradation products and can be implemented easily at a reasonable cost. The process reduces loss of the catalytic metal and the need for make-up ligand. It also provides a more consistent catalytic activity and reduces the production of heavies and associated. The polyunsaturated olefin conversion using this process is 80-95 wt.%.    DETAILED DESCRIPTION - Minimizing (m1) production of at least one phosphonium ion ligand degradation products in a reaction process of polyunsaturated olefin or unconjugated functionalized olefin, in presence of a transitional metal-triorganophosphine ligand complex catalyst to form as a product, by-product or intermediate product a conjugated functionalized olefin having carbon-carbon double bond conjugated to an alpha-electron-withdrawing group, involves conducting the reaction process with a triorganophosphine ligand having a steric and/or electronic property; and/or conducting the reaction process to a polyunsaturated olefin conversion or unconjugated functionalized olefin, respectively. The electron withdrawing group is selected from formyl, keto, ester, acid and nitrile functionalities.    INDEPENDENT CLAIMS are included for:    (1) method (m2) of reverting a phosphonium ion ligand degradation product or its mixture back to triorganophosphine ligands involving treating the reaction product fluid containing the phosphonium ion ligand degradation product or its mixture with an inert gas, hydrogen, and/or synthesis gas, where the phosphonium ion ligand degradation product or its mixture reverts to useful triorganophosphine ligand and comprises an adduct of a triorganophosphine ligand and a conjugated functionalized olefin having a carbon-carbon double bond conjugated to an alpha-electron-withdrawing group;    (2) an integrated process (m3) for carbonylation of a polyunsaturated olefin or its mixture involving a) contacting a polyunsaturated olefin or its mixture with carbon monoxide, optionally in the presence of hydrogen, alcohol or water and in the presence of a transition metal-triorganophosphine ligand complex catalyst and free triorganophosphine ligand to prepare a reaction product containing a transition metal-triorganophosphine ligand complex catalyst, optionally free triorganophoshine ligand, at least one reaction product, by-product and/or intermediate products containing an alpha,beta-unsaturated aldehyde, ketone, ester or acid and at least one phosphonium ion ligand degradation products; b) treating the reaction product fluid from the step (a) with an inert gas, hydrogen, and/or synthesis gas to revert the phosphonium ligand degradation product back to triorganophosphine ligand; c) feeding the reaction product fluid from step (b), containing reduced amounts of phosphonium ion ligand degradation products to a vaporizer or an extractor for separation into a first phase containing reaction products, by-products and/or intermediate products and a second phase containing transition metal-triorganophosphine ligand complex catalyst and optionally free triorganophosphine ligand; and d) recycling the second phase from step (c) containing the transition metal-triorganophosphine ligand complex catalyst and optionally free triorganophosphine ligand back to reaction process step (a).