SketchUp can export its own drawings (.skp) to several 2D graphics image formats including the JPEG (.jpg, .jpeg). You can find the function at File ► Export, which will essentially achieve skp to jpg conversion (or export).
Just be advised that this export function will only export one 2D view of the 3D model, so in case you would import this file back to SketchUp you wouldn't get the original model back. If you want to convert whole mode, use one of the 3D formats instead.