* U.S. rains boost corn, soybean yield prospects

* Wartime loadings in Ukraine, record Russian crop pressure wheat

* Economic uncertainty also curbs grain markets

CHICAGO, Aug 18 (Reuters) - Chicago wheat futures slid for a fifth session on Thursday, pressured by soft export sales, a stronger dollar and continued exports from Ukraine, analysts said.

Soybeans firmed after better-than-expected export sales last week indicated strong demand as U.S. harvest nears, while corn traded near even.

Economic uncertainty also hung over grain markets, as investors assessed recession risks and analysed minutes from the U.S. Federal Reserve's July policy meeting.

The most-active wheat contract on the Chicago Board of Trade (CBOT) 31-1/2 cents to $7.49 a bushel, reaching the lowest on a continuous basis since Feb. 3, 2022.

CBOT soybeans gained 15-1/4 cents to $14.05-1/4 a bushel, while CBOT corn ended 3-3/4 cents higher at$6.15-3/4 a bushel.

Export sales of U.S. wheat during the week ended Aug. 11 were just 207,200, a marketing year low and down 46% from the prior 4-week average.

Demand for U.S. wheat is further muted by a firmer U.S. dollar.

Meanwhile, shipments of Ukrainian wheat continue to leave Black Sea ports, easing global demand. 25 vessels have left under a U.N.-brokered grain export deal.

"All of this is coming to a head," said Mike Zuzolo, president at Global Commodity Analytics. "We’re really in some dangerous areas, technically."

Meanwhile, soybean export sales lent strength to soybean futures, with new crop sales to China boosting demand. U.S. exporters sold nearly 1.4 million tonnes of soybeans last week, surpassing analyst expectations.

Expectations of rain and cooler temperatures in the coming week across parts of the U.S. Midwest muted gains in soybeans and corn.

"We’ve got weather coming at us over the next couple days. That keeps things in check. It’ll be interesting to see how much moisture comes with this system," said Tom Fritz, commodity broker at EFG Group.

U.S. corn export sales reached 849,300 tonnes last week, in line with analyst expectations. (Reporting by Christopher Walljasper; Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; editing by Grant McCool)