If the chromic acid oxidation is performed with stoichiometric oxidant in the presence of diethyl ether as co-solvent (a method introduced by H.C. Brown), the epimerization of l-menthone to d-isomenthone is largely avoided.
Apple cider vinegar isn't likely to be effective for weight loss. Proponents of the apple cider vinegar diet claim that drinking a small amount of apple cider vinegar before meals or taking an apple cider vinegar supplement helps curb appetite and burn fat. However, there's little scientific support for these claims.
Apple cider vinegar is also good for diabetics. To answer your question, apple cider vinegar may help in general weight loss, which would also include reducing your stomach. However, studies have shown that by just doing an apple cider vinegar diet alone, one only loses an average of two pounds per month.