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All 3 posts Subject: Synthesis of dl-Ephedrine Please login to post Down

Rhodium
(Chief Bee)
01-22-03 04:21
No 400342
User Picture       Synthesis of dl-Ephedrine
(Rated as: good read)

dl-Ephedrine^[1]

A mixture of 50 cc. of absolute ethyl alcohol, 7.4 g. of methylphenyl diketone (1/20 mole) and an alcoholic solution of methylamine containing 1.6g (1/20 mole) was reduced catalytically with hydrogen in the presence of 0.1 g. of platinum oxide^[3]. In some experiments there was a long induction period and then the yield was low. This behavior could be obviated by reducing the catalyst first and then adding the reactants. When reduction no longer proceeded, the catalyst was removed by filtration and about half the alcohol removed under reduced pressure. By this means any excess of methylamine was removed. The solution was made just acid with alcoholic hydrogen chloride and evaporated to dryness. The solid hydrochloride was washed with cold acetone and dried. A small amount of pseudoephedrine hydrochloride could be extracted from this by means of hot chloroform and by working up a number of extractions sufficient was obtained for definite identification (mp 164°C; free base, mp 118°C)^[2,3].

The dl-ephedrine hydrochloride was purified by recrystallizing once from alcohol-acetone and melted at 189°C^[2]. The free base was recrystallized from chloroform-petroleum ether and melted at 75°C. The yield was 2.5-4.0 g.

References:
[1] JACS 51, 580 (1929)
[2] Monatsheft 41, 319 (1920)
[3] JACS 45, 2171 (1923)

Organikum
(Hive Addict)
01-22-03 05:20
No 400357
User Picture       See also

Ephedrine:
Patent US1799110 reductive alkylation with platin etc.
Patent GB338412 same with activated aluminium (Al/Hg)
Patent CH146264 same but also with Zn/H2SO4 (no yields named)

dione = diketone

ORG

Post 399486 (goiterjoe: "Maybe in real life, but not here", The Couch)

lugh
(Moderator)
11-03-04 01:29
No 539301
      Acetylbenzoyl
(Rated as: excellent)

Acetylbenzoyl, methylphenylglyoxal and methylphenyl diketone are different names for the same compound, which has a boiling point of 222°C. The above experimental was drawn from JACS 29 580-2 (1929); which was the first of a three part series which included JACS 29 1906-9 & 2269-72 as well wink

The methodology of the synthesis of acetylbenzoyl was discussed in JACS 50 3341-8 (1928):

and Organic Synthesis 23 1-2 (1943)

Two other articles in German of relevance in this matter are Ber 40 737-44 (1907):

and Ber 62 1142-51 (1929):

cool

Chemistry is our Covalent Bond

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	All 3 posts		Subject: Synthesis of dl-Ephedrine		Please login to post		Down


		Rhodium (Chief Bee) 01-22-03 04:21 No 400342				Synthesis of dl-Ephedrine (Rated as: good read)
						dl-Ephedrine^[1] A mixture of 50 cc. of absolute ethyl alcohol, 7.4 g. of methylphenyl diketone (1/20 mole) and an alcoholic solution of methylamine containing 1.6g (1/20 mole) was reduced catalytically with hydrogen in the presence of 0.1 g. of platinum oxide^[3]. In some experiments there was a long induction period and then the yield was low. This behavior could be obviated by reducing the catalyst first and then adding the reactants. When reduction no longer proceeded, the catalyst was removed by filtration and about half the alcohol removed under reduced pressure. By this means any excess of methylamine was removed. The solution was made just acid with alcoholic hydrogen chloride and evaporated to dryness. The solid hydrochloride was washed with cold acetone and dried. A small amount of pseudoephedrine hydrochloride could be extracted from this by means of hot chloroform and by working up a number of extractions sufficient was obtained for definite identification (mp 164°C; free base, mp 118°C)^[2,3]. The dl-ephedrine hydrochloride was purified by recrystallizing once from alcohol-acetone and melted at 189°C^[2]. The free base was recrystallized from chloroform-petroleum ether and melted at 75°C. The yield was 2.5-4.0 g. References: [1] JACS 51, 580 (1929) [2] Monatsheft 41, 319 (1920) [3] JACS 45, 2171 (1923)



		Organikum (Hive Addict) 01-22-03 05:20 No 400357				See also
						Ephedrine: Patent US1799110 reductive alkylation with platin etc. Patent GB338412 same with activated aluminium (Al/Hg) Patent CH146264 same but also with Zn/H2SO4 (no yields named) dione = diketone ORG Post 399486 (goiterjoe: "Maybe in real life, but not here", The Couch)



		lugh (Moderator) 11-03-04 01:29 No 539301				Acetylbenzoyl (Rated as: excellent)
						Acetylbenzoyl, methylphenylglyoxal and methylphenyl diketone are different names for the same compound, which has a boiling point of 222°C. The above experimental was drawn from JACS 29 580-2 (1929); which was the first of a three part series which included JACS 29 1906-9 & 2269-72 as well The methodology of the synthesis of acetylbenzoyl was discussed in JACS 50 3341-8 (1928): and Organic Synthesis 23 1-2 (1943) Two other articles in German of relevance in this matter are Ber 40 737-44 (1907): and Ber 62 1142-51 (1929): Chemistry is our Covalent Bond

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