Their efforts at a parallel investors conference got a boost when ministers announced negotiations on a free-trade area between six Arab Gulf nations - many of them rich in oil and gas - and a South American economic bloc that includes the continent's two largest economies.
The summit beginning on Tuesday is part of an effort by Brazilian President Luiz Inacio Lula da Silva to promote cooperation among developing countries.
It is also aimed at countering the dominance of the United States in the global areas of politics and trade.
The trade zone would link nations of the Gulf Cooperation Council - Saudi Arabia, the United Arab Emirates, Kuwait, Oman, Bahrain and Qatar - with the Mercosur bloc, whose fully-fledged members are Argentina, Brazil, Paraguay and Uruguay.
Abdulrahman al-Attiyah, secretary-general of the Gulf council, did not outline a timeline for the negotiations, but said clinching a deal "will not take long, because the common interest is there".
Business leaders trolling the vast convention centre for possible deals agreed.
Eduardo Gomez, CEO of an Uruguayan hi-tech consulting firm, said the two regions would make good partners. "They have the petrodollars and they want to go to the American markets, but they don't have the products," he said.
Representatives of Latin American countries were trying to inform Arab business leaders about their markets.
A few steps away at a stand promoting Bolivia, government officials offered a workshop to let the Arabs know that the troubled Andean country is looking for investments to improve its crumbling infrastructure, build mines and cut forests for furniture-quality wood.
"We want to make a big push to open up new markets and attract new investment," said Isaac Maidana, the country's vice-minister for international relations. "We have never had a tight relationship with the Arabs before, but these areas could be of big interest."
Brazil was pushing its defence industry, which in the 1980s was the world's eighth-largest based on strong demand for Brazilian armoured personnel carriers, reconnaissance and anti-aircraft vehicles, troop carriers and rocket launchers.