Describir: Chemoselective preparation of 1,1-diacetates from aldehydes, mediated by a Keggin heteropolyacid under solvent free conditions at room temperature

 __   __    _____    _    _    _    _    _    _    __   __    ______  
 \ \\/ //  |  ___|| | || | || | || | || | \  / ||  \ \\/ //  /_   _// 
  \   //   | ||__   | || | || | || | || |  \/  ||   \ ` //     | ||   
  / . \\   | ||__   | \\_/ || | \\_/ || | .  . ||    | ||     _| ||   
 /_//\_\\  |_____||  \____//   \____//  |_|\/|_||    |_||    /__//    
 `-`  --`  `-----`    `---`     `---`   `-`  `-`     `-`'    `--`     
                                                                      
   ___    
  / _ \\  
 | / \ || 
 | \_/ || 
  \___//  
  `---`