Let us discuss this together please. I have included a description and a pdf containing different methods of removal of the methyl group from codeine.

Here is one I am having trouble finding information on.

It is the demethylation of aryl methyl ether using Beryllium Chloride (BeCl2) in toluene as the solvent with stirring and gentle heating for 5 hours. I think that xylene or benzene can be used as well.
Yield was 95%.

I do not know what the yield will be with codeine/3-methylmorphine.

Reference:

Tetrahedron
Volume 52, Issue 43, 21 October 1996, Pages 13623-13640
doi:10.1016/0040-4020(96)00815-0

BeCl2 as a new highly selective reagent for dealkylation of aryl-methyl ethers

Hashem Sharghi* and Fatemeh Tamaddon
Department of Chemistry, Shiraz University, Shiraz 71454, Iran.

Abstract

An efficient and simple method is introduced for the selective removal of methyl group from poly aryl-methyl ethers, in some important derivatives of benzophenones, xanthones, anthraquinones, aryl esters, benzamides and nitroanisoles with BeCl2.
An efficient and simple method of selective demethylation of polyaryl-methyl ethers with BeCl2 is described.



From the pdf:

SnO2

"SnO2 in CH2Cl2 was used in selective
demethylation of compound 1 to efficiently give
compound 2 under mild conditions in high yield
(95%) (Scheme 5). As a semiconductor, SnO2 is
particularly useful from an environmental
viewpoint, because it is almost nontoxic, stable,
and inexpensive[5]."


Reference:
[5]TETSUYA T, TSUYAHO O, IWAO O ,et al.
Semiconductor-mediated oxidative dimerization of
1-naphthols with dioxygen and O-demethylation of
the enol-ethers by SnO2 without dioxygen[J].
Trahedron Letter 2004 60:10681-10693.

Tetrahedron
Volume 60, Issue 47, 15 November 2004, Pages 10681-10693
doi:10.1016/j.tet.2004.09.003 | How to Cite or Link Using DOI

Semiconductor-mediated oxidative dimerization of 1-naphthols with dioxygen and O-demethylation of the enol-ethers by SnO2 without dioxygen

Tetsuya TakeyaCorresponding Author Contact Information, a, E-mail The Corresponding Author, Tsuyoshi Otsukaa, Iwao Okamotoa and Eiichi Kotania

Showa Pharmaceutical University, 3-3165 Higashi-tamagawagakuen, Machida, Tokyo 194-8543, Japan

Abstract

Oxidative dimerization of 1-naphthols 1 with dioxygen in the presence of a semiconductor, such as SnO2, ZrO2, or activated charcoal, as a catalytic mediator takes place selectively to give the corresponding 2,2?-binaphthols 2 or 2,2?-binaphthyl-1,1?-quinones 3 in excellent yields without light irradiation. The catalytic activity of SnO2 could be fully restored by appropriate reactivation treatment after the oxidation. In addition, SnO2 without dioxygen catalyzes selective O-demethylation of the enol-ethers 3 to 4.

Thank you Slash. I meant to make this general discussion of methods for everyone. If you want to share more it would be good for all bees.

This article is from Rhodium's collection 

An Improved Method for O-Demethylation of Codeine

Other better mothods exist :

- Lithium iodide with a activated pyridine such as collidine
- BBr3 and other lewis acid
- Thiophenolate salt
- MsOH / Methionine

Has anyone here ever tried to demethylate an opiate

Here is a patent on dealkylation of opioid ethers, but one's time would be much better spent using the info from the second article below to N-demethylate so that one could turn their nor-whatever into N-phenethyl-whatever.  Much bigger jump in potency.  I also have an article on making the N-furan-2-ylethyl opiate from the nor-material but it's a lot more trouble than making the N-phenethyl