The First Minister praised everyone for "pulling together" to pin down an agreement, including the UK and Scottish governments.
But he said it was ridiculous for anyone to suggest the heft of the UK Government had brought about the resolution and warned no-one should use the drama of the past 72 hours to score political points in the referendum debate.
He said: "People who attempt to play constitutional politics in this will end up with egg right over their face."
Prime Minister David Cameron praised those who worked to preserve the plant, a key part of the Scottish and UK economy.
The reversal by Swiss-based Ineos of its initial decision to close the plant followed acceptance by the Unite union of a survival plan for the business. This includes a three-year pay freeze, an end to the final salary pension scheme and a promise of no strike action for three years.
Just 48 hours before, the owners made clear that they would shut down the petrochemical plant, on which the jobs of 800 employees and 2000 contractors depended, because the site workers had refused to sign up to the proposed changes. Jim Ratcliffe, the chairman of Ineos, said that the union's about-turn was a "victory for common sense" and that a multimillion-pound investment would now be made into the site.
But he decried the personal attacks made against him, saying: "At the end of the day, I am going to have to write a cheque for £300 million.
"I don't think it's very bright of the unions to abuse the person who is going to commit £300m, which is what Grangemouth needs to survive."
Earlier in the day, staff cheered loudly when they were told news of the turnaround at a mass meeting with managers.