A New Method for the Synthesis of Ephedrine.pdf

No.

11.E

147

37.

A New Method

for the

Synthesis

of Ephedrine.

By Shinsuke MURAHASHI

and Nobue HAGIHARA.

Instituteof Scientific

andIndustrialResearch,OsakaUniversity.

OsakaDaigakuSangyoKagakuKenkyujo,

Dec.12,1947.)

The synthetic method of acetylene alcohol by the condensation of

acetylene and aldehyde in presence of catalysts under pressure was

studied by I. G. in Germany (W. Reppe Brit. 508062). Later the con-

densation of acetylene formalin developed into many interesting pro-

blems of industrial chemistry (Modern Plastic : Feb. 169, 1946).

Investigating along this line since 1942, Murahashi and Ryutani

made related researches leading up to the study of nylon (Gosei Sen-

i-Kenkyu, Synthetic Fibre, Vol. II, Oct. 1944) and also the study of

higher alcohol (a glycerine substitute) in the war time. In the course

of the investigations, new important observations were made upon the

property and preparation of the catalyst involved. Such studies which

have not hitherto been made by other investigators in this country are

being continued by the present authors. Recently, they made investi-

gations on the condensation of acetylene, acetaldehyde, and formalin,

succeedingint he preparation of pentin-(2)-diol-(1.4) (Material for the

preparation of Atebrin, Plasmochin).

It so happened that the authors, in face of the current shortage

of ephedrine wished to try out the application of the foregoing method

for its synthesis. The following new course for the synthesis of

ephedrine was proposed and carried out. Namely, under the presence

of catalytic copper, acetylene and benzaldehyde were condensedunder

high pressure (14-45 atm. pressure) to form acetylene alcohol.

(Comm.

by R.MAMMA,

M.I.A.,

•CanCH (the first step)

Next, in the presence of a mercury salt as catalyst, water was

added to form the following ketonic alcohol. From the latter, it is

proposed to synthesize ephedrine.

CgHSCH(OH)C-CH(I)H~2C6HSCH(OH)COCH3

C6H5CHO

+ HC= CH --~ C5H5CH(OH)

(the second step)

The above acetylene alcohol (I) gives diketon (II) by copper oxide

oxidation.

-° C5HSCOCOCH3(II)

(I) and (II) are hitherto important material for the synthesis of ephedrine.

It is well known that they give by catalytic reduction in presence of

methyl amine dl-ephedrine.

As the result of studies of the first step in foregoing process as

regards catalyst, pressure, pH. and fatigue of catalyst, the authors

can now make successful reaction with good yield. For the second

step also, various conditions to bring about good yield have been also

discovered. Moreover, a favourable condition under which the second

C6HSCH(OH)COCH3(I)

148

S. MURAHA.SIII

and N. HAGIHARA.

[vol. 23,

step can be smoothly proceeded

from

the first, only by the elimination

of the catalyst

by filtration

have

been determined.

Thus from acetyl-

ene, the ketonic alcohol is obtained

directly

in the yield of 82-850

benzaldehyde

used.

CsH5CHOc1x~ ' >

C6H5CH(OH)000H3

As to the third

step, it is still desirable to make further

investigations,

however,

by this new method

of synthesis,

production

of ephedrine

an industrially

large

scale has become

evidently

possible.

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