Operator Ineos announced on Wednesday that it would shut the petrochemical arm of the central Scotland facility, with the potential loss of 800 jobs.
Staff at the site are waiting to hear if the firm will grant a reprieve to the closure-threatened operation after the Unite union reversed its opposition to a survival plan aimed at securing the site's future.
First Minister Alex Salmond said he believed people have been going the extra mile to reach a deal and he was now "very confident that we'll get a much better announcement" from the firm today.
"We have reason to be confident that we're looking at an infinitely better prospect than we were just 48 hours ago," he said.
He added: "My estimation is that I would now be very hopeful indeed that there will be a change in position from Ineos today and I'm absolutely certain there's a future for chemicals in Grangemouth."
Asked if he believed both the site's petrochemical plant and refinery have a future under Ineos, he said: "I believe there will be a change of position from Ineos today and that will be a favourable change in position.
"My reason for saying that is that everybody has been going that extra mile I've called for.
"Given that only 48 hours ago we were looking at a major industrial catastrophe in Scotland, I think we're in a much better position this Friday morning.
"We'll hear today, but I would be very hopeful indeed that there's a change in position from the company and I would be absolutely certain there's a future for the chemicals industry in Grangemouth."
Mr Salmond said the trade unions have now offered that there will be no industrial action for three years.
"That's an indication that however we got to this impasse two days ago, there has now been substantial movement of people anxious to save their jobs, their livelihoods and their plants," he told the programme.
Ineos has been considering a change in position by the Unite union whose members now say they will commit to a plan aimed at securing the plant's future.
The petrochemicals plant and adjoining oil refinery making up Scotland's largest industrial complex was shut down last week in advance of a planned walkout over pay and conditions.
Ineos did not restart the site after Unite called off the strike but wrote to staff asking them to sign up to changes such as a pay freeze and the closure of the final salary pension.
The company insisted on Wednesday that it had no alternative but to close the plant after it failed to persuade its staff to accept the survival plan but Unite general secretary Len McCluskey said yesterday that the union would embrace it "warts and all".
A statement is expected from Ineos today on the petrochemical business which employs 800 people directly and a further 2,000 sub-contractors.