The whole pre-ban containing 10% 3-mmc I think originated from this post on another forum. Whether it's true or not I have no idea so don't jump on my back if it's a load of bollocks.
China banned production of the meph pre cursor
4-methylpropiophenone which contains up to 10% 3-methylpropiophenone (technical grade reagent). Separation of 3-methylmethcathinone from 4-methylmethcathinone is difficult. On large scale, multiple recrystallizations are required which I doubt most RC manufacturers would do because of lost material and thus lost profit - hence the impurity. Thats why chinese meph was different as it contained 3-mmc as a by product which happened to give you a better buzz,although bad for your health.They were losing too much product in washing it out.China was main world producer of 4-methylpropiophenone so when it dried up i presume thats when india started producing meph but were unable to get the banned pre cursors so used probably one of these methods,both produce mephedrone but none of them contain 3-mmc in the final product.Cleaner yes but the buzz is not as intense as the 3-mmc was helpin the chink gears potency.
----------
India synth option
It can also be produced by oxidising the ephedrine analogue (4-methylephedrine) using potassium permanganate dissolved in sulfuric acid. Because 4-methylephedrine can be obtained in a specific enantiomeric form it is possible to produce mephedrone consisting of only one enantiomer. There is a danger associated with this method as it may cause manganese poisoning if the product is not correctly purified.[1]:17
----------
india synth option
A stereospecific form of (S)-mephedrone could be prepared via Friedel–Crafts acylation. The first step in the synthesis would react toluene and (S)-N-trifluoroacetylalanoyl chloride in the presence of aluminium chloride, then deprotect the intermediate with hydrochloric acid-propyl alcohol . This would produce (S)-4-methylcathinone, which could then be methylated to produce mephedrone
There are more synth recipies about but none contain 3-mmc in the final product unless 4-methylpropiophenone was used as the pre cursor.