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.
One of the health benefits of regularly drinking a mixture of honey and apple cider vinegar is that it can assist in losing weight. In my article on using apple cider vinegar for weight loss, you can find out how ACV helps to suppress appetite, control blood sugar levels, and prevent fat accumulation.