Antioch College managed to stave of bankruptcy yesterday at least for the immediate future, when a trustee bailed the college out of its financial straits with a $700,000 contribution from his own pocket.

Antioch President William Birenbaum, speaking to reporters after a marathon closed-door meeting here, refused to name the $700,000 donor. But Birenbaum said that hefty donation - plus smaller contributions from other trustees made during the nine-hour meeting - will carry Antioch through the summer, "with some hardship."

Birenbaum said the anonymous donor, identified only as a member of the trustees' finance committee, attached a single condition to his last-minute donation - that "an allout fight for this institution's survival is worth fighting for."

The gift was truly an 11th-hour reprieve for the small liberal college, which had been given a Monday-morning deadline to come up with at least enough cash to pay the overdraft and the interest rates on all its defaulted loans. Still, the donation was only a temporary reprieve, and Birenbaum stressed that the trustees also approved a number of belt-tightening measures.

Specifically, the president said that two of Antioch's 10 branch campuses would be either dropped or consolidated as part of a general reorganization. He declined to name the two, but said the board did decide that the Baltimore campus would remain open.

The trustees also formed a committee with Antioch lawyers "for the exploration and further adoption of corporate legal restructuring." That means, Birenbaum said, deciding how Antioch can "pay back its debt in a reasonable way and remain solvent."

To keep Antioch operating during the summer months, the trustees decided that some branch units that would not break even financially would not offer summer programs. The decision, he said, was up to the individual administrators of those branches, based on their own budget estimates.

Also during the meeting, from which the press and Antioch students were barred, the trustees voted for a reorganization plan that essentially embodied all the elements of Birenbaum's 15-point plan presented at Friday's opening session. The plan centers on:

A constitutional convention on the future of higher education at Antioch, scheduled for January.

Inclusion in the fall curriculum of a number of courses on the governance of a university, to "enable the technical problems" of Antioch's finances and administration to be studied, in a classroom setting, before the January convention.

The trustees voted "no" on whether Antioch should declare bankruptcy, Birenbaum said.

There had also been speculation that the trustees would vote for greater decentralization among Antioch's branch colleges - a sort of "every branch for itself" approach. Birenbaum said that, after much discussion, the trustees voted to "uphold" the integrity of the university."

In mid-May, the school could not meet the payroll for its 862 employes, including the president. Teachers, administrators and staff have been working without pay since then, but Birenbaum said yesterday the normal June pay schedule should resume.