Almost all the boronic acids and esters are soluble in water, thus its storage should be avoided in humid environments. The common industrial production of boronic acids is the reaction between borax and sulfuric acid (Na2B4O7+H2SO4+5H2O→4H3BO3+Na2SO4). https://buildingblock.bocsci.com/products/boronic-acids-and-esters-3223.html