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All 13 posts   Subject: Nitrostyrene Reduction to Amine Literature Search   Please login to post   Down

 
    Rhodium
(Chief Bee)
12-19-02 23:03
No 390917
User Picture  		      Nitrostyrene Reduction to Amine Literature Search     

This should be every reference in Beilstein concerning the reduction of nitrostyrenes to phenethylamines and amphetamines, using any reducing agent imaginable. Please post here if you find anything of interest in the pile, I haven't gone through the list myself yet.

https://www.rhodium.ws/chemistry/nitrostyrenes/index.html 		 
 
 
 
    roger2003
(Stranger)
12-29-02 16:20
No 393848
       Article found: http://nr.stic.gov.tw/ejournal/C...     

Article found:

http://nr.stic.gov.tw/ejournal/ChiChemSociety/qr_abs.cfm?UnionCode=2973:


JOURNAL OF THE CHINESE CHEMICAL SOCIETY
 
 
49(4), 2002, pp.505-508

--------------------------------------------------------------------------------
 
Low-valent Ruthenium Induced Simultaneous Reduction of Nitro Group and C-C Double Bond in Nitroolefin 1-Phenyl-2-nitropropene-1
 
Yanjun Li* and Taeko Izumi
Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata University, 3-16 Jonan 4-Chome, Yonezawa, 992-8510, Japan
 
Abstract.     The reduction of 1-phenyl-2-nitropropene-1 (1) on using ruthenium complexes was studied in detail in order to correlate this method with those previously recorded in the literature for the hydrogenation of nitroolefins. A variety of products was isolated by varying the reaction temperature and solvent. Among them was 1-phenyl-2-propylamine (4), completely reduced from the selective both double bond and nitro group. 1-Phenyl-2-propanol (5) was observed due to reduction of phenylacetone at 125 ¢XC in the presence of ruthenium catalyst. When reaction temperature was lower than 125 ¢XC, by employing RuCl2(PPh3)3 complex, 1-phenyl-2-nitropropane (2) and phenylacetone (3) were obtained, respectively. Ru-BINAP complexes were attempted to produce chiral amine from starting material 1-phenyl-2-nitropropene-1 (1). 

Complete article here:

http://nr.stic.gov.tw/ejournal/ChiChemSociety/2002/EJ52-2002-505.pdf:
roger2003 		 
 
 
 
    hypo
(Hive Addict)
01-16-03 00:29
No 398546
       electrolysis
(Rated as: excellent) 		    

i had a look at some of the electrolysis refs. i found one of the articles to be very interessting. the others were mostly known stuff. here's the interesting one:

Chem.Ber.;124;10;1991;2303-2306

a short, but highly interesting article. fortunately it is in english, so i don't have to translate it! i'll scan and post asap (if we don't have it already). as a teaser the abstract:

1-Nitroalkenes are reduced in high yields at -0.3 to -0.5V (vs.SCE) at a mercury or graphite electrode to oximes. At higher cathodic reduction potentials (-1.1V) primary amines are selectively obtained in fair yields. Nitroalkadienes are selectively reduced at the double bond conjugated with the nitro group to either the oxime or the amine.

yield given for P2Poxime: 91% with mercury electrode or 85% with graphite electrode
yield given for PMP2Poxime: 91% with mercury electrode
yield given for amphetamine: 66% with mercury electrode

we learn alot in this article! it might be better to do nitropropene => oxime and reduce that by conventional means! one of the side-reactions of the oxime electrolysis is formation of the ketone, so treatment of the electrolyte with hydroxylamine increases the yield. i don't know, but i like it!

ok, it can't hurt, so here a summary of the other articles:

Monatsh.Chem.;79;1948;72,77

german text: papaverine junkies on the search for a papaverine analog with displaced methoxy groups. for this they need phenethylamines.
the nitro->amine reduction is done with Al/Hg(!). i have no idea, why i fetched this one!? must have been sleepy...

a quick translation of the condensation of benzaldehyde with nitromethane (the known KOH method):

2,3-dimethoxy-w-nitrostyrene and beta-(2,3-dimethoxyphenyl)-alpha-ethanol.

10g 2,3-dimethoxybenzaldehyde and 4g nitromethane are dissolved in warm EtOH and cooled to -10°C using a freezing mixture. There was no precipitate. To this solution is added a strongly cooled KOH solution in EtOH (4.5g KOH, 13ccm EtOH and 8ccm H2O) in small aliquots. The temperature was kept below 0°C and the reaction strongly stirred. Mostly the condensation to the aci-compound was finished after a short while (complete dissolution of the reaction product in water). The nitrostyrene was precipitated by pouring the reaction in 200cm icecooled n-H2SO4. The nitrostyrene was easily recrystallised from EtOH, but the raw product was well suited for further reactions. Raw yield: 11.7g (93% of theory). mp 87-88°C.

If the decomposition of the potassium salt of the pseudo acid is done with acetic acid (10ccm 50% for the above reaction) instead of H2SO4 then the corresponding nitro-alcohol precipitates. It can be recrystalised from pet. ether gived fantastic crystals and melts at 66-68°C. Raw yield: 10.3g

then there's a reduction of the nitrostyrene to the oxime with zinc and a reduction of the oxime to the amine with Na/Hg. (400g amalgam/5g oxime, wtf!?)

a quickie of the reduction of the nitrostyrene to the amine:

1g 2,3-dimethoxy-w-nitrostyrene is dissolved in 10ccm AcOH, 10ccm EtOH and 10ccm H2O with heat and 2g Al-turnings were added. The reduction started after addition of a small amount of HgCl2. After standing for 2h at 20°C, the reaction was finished on a warm waterbath. The workup was done in the same way as with the oxime. [A/B, then distillation] Distillation gave 0.58g freebase, which gave 0.67g of the picrate.

the rest of the text is on isochinolines and stuff...

J.Amer.Chem.Soc.;54;1932;271,273

synthesis of dl-beta-phenylisopropylamines. quote: "In a previous paper it was demonstrated that the introduction of a methyl group into the side chain of beta-phenylethylamine furnishes a compound differing from the latter with regard to certain of its effects when administered as drug compound." no, really? anyway, they prepare plain, para-methoxy, and 3,4-dimethoxy amphetamines. condensation of the aldehyde with nitroethane and n-amylamine, then electroreduction:

0.1 Mole of phenylnitropropylene dissolved in catholyte of 100cc of ethanol, 50cc of acetic acid and 50cc of 12N sulfuric acid was placed above a 40-sq cm mercury cathode in a porous cell surrounded by a 3N sulfuric acid anolyte with a water cooled lead anode. Four amperes was passed for twenty hours and the temperature in the catholyte was kept between 80 and 40°.

The resultant catholyte was partially evaporated, then made strongly alkaline and the separated basic layer taken up with benzene. The desired amine was then extracted from the benzene by neutralising with dilute hydrochloric acid and separating the aqueous layer. This was evaporated and then the product crystallized. From phenylnitropropene, 0.02 mole of dl-beta-phenylisopropylamine hydrochloride, melting at 144-145° was obtained. The melting point of this compound has been reported as 145-147°C.

From 4-methoxyphenylnitropropene, 0.02 mole of dl-beta-4-methoxyphenylisopropylamine hydrochloride melting at 208-209° was obtained. The melting point of this compound has been reported as 210°.

From 3,4-dimethoxyphenylnitropropene, 0.02 mole of dl-beta-3,4-dimethoxyphenylisopropylamine hydrochloride melting at 151-152° was obtained. The melting point of this compound has been reported as 144°.

(the interesting thing to note: electro reduction works for amphetamines too)

J.Prakt.Chem.;137;1933;339,349

this is the famous mescaline electro synthesis, found on rhodium's (even in russian!) with diagram and everything. the benzaldehyde + nitromethane condensation is done with KOH.

Chem.Ber.;74;1941;459,462

now this is a strange paper (imho). again they are interested in papaverine chemistry (isochinoline formation). they do electroreduction of the nitrostyrene, they also make the benzylcyanide via the rhodanine method found on rhodium's site. (a highly strange syntheses! rhodium: maybe you should mention that there is H2S evolution in the oximation step (yeah obviously so, but still...))

anyways, here the electroreduction (translation from german):

beta-(2,5-dimethoxy-phenyl)-ethylamine

9g of the w-nitrostyrene was suspended in a mixture of 200ccm EtOH, 100ccm AcOH, and 30ccm conc. HCl and reduced at a lead cathode for 4h at 30-35°C (current density: 0.07A/cm^2 of cathode). The thus obtained colourless solution was worked up in the usual manner and 4g beta-[2,5-dimethoxy-phenyl]-ethylamine was obtained, distilling at 148°/8mmHg. The hydrochloride gave colourless needles, mp 139°, corresponding to the literature.


Chem.Ber.;66;1933;450

german text on the constitution of laurotetanine. first of all, a strange way of making phenyl-acetic acids. it's the hippuric acid method found on rhodium's site (yeah, as usual tongue)

electroreduction of 3,4-dimethoxy-benzaldehyde (quick and dirty translation from german):

The reduction of the latter compound [the styrene] was performed under conditions given by Prof. R. Robinson in a private message, for which we are very grateful. A heavily stirred suspension of 14g nitrostyrene in a mixture of 200ccm EtOH, 200ccm AcOH and 80ccm conc HCl was reduced by electrolysis with a current density of 0.07A/cm^2 of cathode surface. The temperature was kept below 15°C. The reduced solution was filtered and the volume concentrated to 1/4th under vacuum. Then it was diluted with the same volume of water, washed with ether to remove non basic compounds, basified with NaOH and extracted with chloroform. After drying with potash and evaporation of the chloroform, the base is vacuum distilled. (bp 147°).

The cell used for the reduction was standing in a 2L beaker and consisted of an exterior anode chamber with 600cm volume. The anode was a rectangular piece of lead of about 2mm thickness, 27cm length, and 10cm height which cylindrically enclosed the cathode chamber. The latter consisted of a porous porcelain container with 15cm height and 7.5cm diameter. The cathode was made out of a 2mm thick lead sheet (13x2) and had 40 little holes with 5mm diameter each. The anode abutted tightly to the inside of the porcelain container so that there was enough place for the stirrer. The whole container was standing in ice water during the reduction. The electrolyte in the anode chamber was 20% sulfuric acid.

ps: sorry for the quick & dirty job, i can't motivate myself right now... tongue 		 
 
 
 
    moo
(Hive Bee)
01-16-03 00:48
No 398553
       tee-hee     

Post 265592 (moo: "Re: Nitrostyrene or Nitropropene electrochem reduction", Chemistry Discourse) wink 		 
 
 
 
    Rhodium
(Chief Bee)
01-16-03 01:09
No 398557
User Picture  		      electrochem is too little used     

Hypo: I have added that H2S warning to rhodanine.html. Thanks for posting all these abstracts/highlights.
I'm very interested in hearing about that first electrochem reduction article you posted a teaser from.

Could you (or any other french-speaking bee) translate https://www.rhodium.ws/pdf/archive/benzodioxole.deriviatives.pdf - it seems like it contains loads of useful material. 		 
 
 
 
    hypo
(Hive Addict)
01-16-03 10:07
No 398659
       oh :)     

moo: i guess i should learn to utfse blush

rhodium: article is on the way, i'll have a look at the benzodioxole thingy... 		 
 
 
 
    GC_MS
(Hive Bee)
01-16-03 12:08
No 398674
User Picture  		      looks     

Looks a good article indeed, especially since it contains good explanations about how the reactions have to be conducted. SWiM is not a native French speaker, but his knowledge of the language goes further then "voulez-vous jouer ma flute?" wink
The safrole synthesis looks very easy... and so does the synthesis of piperonal.
Ave Hive, synthetisandi te salutant! 		 
 
 
 
    Rhodium
(Chief Bee)
01-16-03 16:09
No 398713
User Picture  		      Ber 124, 2303-2306 (1991) submitted in email to me     

https://www.rhodium.ws/pdf/nitroalkene.electroreduction.pdf 		 
 
 
 
    Rhodium
(Chief Bee)
01-18-03 23:29
No 399504
User Picture  		      Ber 124, 2303-2306 (1991)     

I have now uploaded a much cleaner scan of Ber 124, 2303-2306 (1991) (https://www.rhodium.ws/pdf/nitroalkene.electroreduction.pdf) 		 
 
 
 
    hypo
(Hive Addict)
01-23-03 19:46
No 400894
       transl. of benzodioxole organo-magnesium article
(Rated as: excellent) 		    

there's one sentence, i don't know what they're talking about (marked with [XXX]):
wtf is "une ampoule а chlorure de vinyle"? ampoule is a lightbulb or an ampoule (doh!),
chlorure de vinyle is vinylchloride. but together?


N°314-Synthesis of methylenedioxy-1,2-benzenes.

(Safrole, piperonal, piperine, ...).

by Claude Feugas.
Bull. Soc. Chim. France 1892-1895 (1964) (https://www.rhodium.ws/pdf/benzodioxole.deriviatives.pdf)


(Laboratorium for organic synthesis, 1, rue Victor-Cousin, Paris, 5e.)

(Paper received 11-Apr-1964)


Reacting 4-bromo-1,2-methylenedioxy-benzene or its higher homologue 2,2-bis-ethyl-5-bromo-benzodioxole with magnesium in tetrahydrofurane gives organo-magnesium compounds [XXX]. These new compounds allow to introduce the methylenedioxy-benzene heterocycle into numerous [XXX] compounds in a single step. The piperine derivates safrole, isosafrole, piperonal, piperonylic acid and alcohol, 4-methyl-1,2-methylenedioxy-benzene, alpha-ethyl-piperonylic alcohol, piperonylacroleine, piperic acid and finally piperine have thus been synthesised.

Many natural or biological active compounds contain in their structure the 1,2-methylenedioxy (1,3-benzodioxole) group. These alkaloids and flavones have been extensively researched and some of them have interesting pharmaco-dynamic applications. Right now there is a renewed interest in these compounds due to the recent discovery of their insecticide and fungicide properties (1-9), and especially their antimitotic properties in certain forms of cancer (10-17). A big number of structural derivates were prepared and systematically explored (3, 10, 15, 16, 17). One limiting factor in these studies has been the difficulty in synthesis, because the acetalisation of a substituted diphenol already in place is nearly impossible (18). The importance of an organo-metallic derivate of 1,2-methylenedioxy benzene became quickly apparent; it would allow the addition of the heterocycle during any part of the synthesis by various reactions with reaction conditions favourable for the stability of complex molecules. Nevertheless, until now all attempts at the synthesis of organo-magnesium compounds were failures (10-19a). The same was true for attempts to prepare organo-lithium compounds by direct action of 4-bromo-1,2-benzene on lithium, exchange reagents under common temperature and dilution conditions, or reaction between butyl-lithium and 4-bromo-1,2-methylenedioxy benzene (10). Lithium reagents destroy the dioxole cycle (10, 20, 21, 22). Concerning 4-bromo-1,2-methylenedioxy-benzene we have now discovered a solvent effect analogous to the one already noted during the study of the reaction of halogenated ketals with magnesium (24-26). Contrary to the situation in ether, in which most of the mentioned experiments took place, in tetrahydrofurane, the reaction between 4-bromo-1,2-methylenedioxy-benzene and magnesium proceeds "normally", giving the organo-magnesium compound with good yields. The utilisation of this new Grignard reagent permitted new syntheses of a certain amount of natural piperine derivates.

Safrole was obtained by condensation of 4-bromo-1,2-phenyl-magnesium with allyl bromide:


Piperonal (heliotropine) by condensation with n-methylformanilide:


Piperonylic acid by carbonatation of 4-bromo-1,2-methylenedioxy-phenyl-magnesium:


Piperonylic alcohol by condensation of 4-bromo-1,2-methylenedioxy-phenyl-magnesium with trioxymethylene:


alpha-ethylpiperonylic alcohol by condensation of the organo-magnesium compound with propanal:


The simple dehydration of alpha--ethylpiperonylic alcohol gives isosafrole:


4-methyl-1,2-methylenedioxy-benzene was prepared by condensation of 4-bromo-1,2-methylenedioxy-phenyl-magnesium with dimethylsulfate:


Piperonylacroleine by condensation of the organo-magnesium compound with 1-(N-phenylmethylamino)-prop-1-ene-3-al:


The yield of the condensation with the higher vinyl-derivate [original: vinyloge] 1-(N-phenylmethylamino)-penta-1,3-diene-5-al was very low.

Piperic acid is synthesised by Doebner reaction with piperonylacroleine followed by decarboxylation:


Piperine, the alkaloid of black pepper, by reaction of piperic acid chloride with piperidine


It is equally possible to prepare an organo-magnesium compound using 2,2-bis-ethyl-5-bromo-1,3-benzodioxole. Like in the previous case, this reaction behaves "normally" only in THF. The condensation with dimethylsulfate gives the expected product:


The structure of 2,2-bis-ethyl-5-methyl-1,3-benzodioxole was verified by acid hydrolysis, which gave 4-methyl-pyrocatechol. 		 
 
 
 
    hypo
(Hive Addict)
01-23-03 19:47
No 400895
       pah... > 10k chars :/
(Rated as: excellent) 		    

Experimental part


The melting points were determined using a Kofler apparatus. The pure products were analysed and infrared (Perkin-Elmer "Infracord" spectrophotometer) and UV (Perkin-Elmer 137 U.V. spectrophotometer) spectra were recorded. The analyses and the absorption spectra were in accordance with the structures; being already published in most cases, they are only detailed in some cases. All encountered 1,2-methylenedioxy-benzenes derivates had IR-absorption peaks at v=1480 cm-1, 1250 cm-1, 1040 cm-1, 920 cm-1. The micro-analyses were done by the Microanalysis Service of the "Faculté des Sciences de Paris"

1,2-Methylenedioxy-benzene

Different methods (27, 28, 29, 30) were tried for the synthesis of this compound. None gave very satisfactory results. The same is true for many other attempts, either by direct acetalisation in benzene or chloroform, with or without catalyst (tosic acid, ferric chloride), or by exchange between pyrocatechol and bispropoxymethane, or by condensation of the disodium derivate of pyrocatechol (by sodium hydride) with dibromomethane in THF or dimethylformamide. The yields were below 20%

bp17=68°; nD21=1.5390

4-Bromo-1,2-methylenedioxy-benzene

This compound is prepared by direct action of bromine vapours on 1,2-methylenedioxy-benzene in acetic acid (31).
Yield = 89%

bp17=114°; nD21=1,5838
Analysis C7H5O2Br: Calc. %: C 41.83 H 2.51
                   Found  :   42.11   2.68

Reaction with magnesium

I. In tetrahydrofurane

The Gilman test was performed using the following procedure: 0.5ml organo-magnesium compound solution, obtained by reaction of the halogen derivate with some magnesium turnings, cleaned by a drop of dibromoethane, are added to 1ml of 0.5% Mischler ketone solution in benzene. The mixture is brought to boil, cooled and hydrolysed (2 ml H2O), shaken, and some drops of 0.5% iodine solution in acetic acid are added. A deep blue colour appears, corresponding to a positive test.

The organo-magnesium compound was prepared in a 250ml flask with multiple necks equipped with a stirrer, a cooler, a thermometer, a vinylchloride bulb and possibly a nitrogen connection. The reaction was moisture protected with calcium chloride drying tubes. The magnesium turnings (1.2g) were covered with 20ml anhydrous THF (the commercial THF, after long standing on potassium, is distilled twice over potassium, then over sodium and finally stored over sodium wires). The reaction is started by adding two drops of 1,2-dibromoethane, then 4-bromo-1,2-methylenedioxy-benzene (0.05 mol in an equal volume of solvent) is added drop wise to the flask such that the temperature is kept below 55°. The reaction becomes more or less yellow-green. After the addition is finished, the same temperature is maintained for 45m.

Hydrolysis in alkali conditions is done by pouring the organo-magnesium solution in a mixture of ice (100g), ammonium chloride (10g) and ammonia (5 ml of 10N solution) while stirring; the organic phase is decanted, the aqueous phase extracted with ether (3x50ml), the combined organic phases are washed with water (20ml), dried over potassium carbonate or sodium sulfate; the solvents are evaporated, the residue is distilled then fractionated on oil bath. One thus obtains 1,2-methylenedioxy-benzene identical (constants, spectrography) to the previous compound. Yield = 77%

II. In ether

The Gilman test gives various results, more often than not positive.
If one attempts to prepare the organo-magnesium compound, one notes the apparition of a persistent whitish cloudiness and the reaction stops despite long heating (7h). After hydrolysis one obtains basically the unchanged starting product, 4-bromo-1,2-methylenedioxy-benzene.

4-Allyl-1,2-methylenedioxy-benzene (safrole)

The organo-magnesium solution obtained using the previously given method is added to refluxing allyl bromide. After alkaline hydrolysis, one isolates safrole. Yield = 87%

bp0.2 = 62-63° nD = 1.5389 (32a)

3,4-Methylenedioxy-benzaldehyde (piperonal)

The organo-magnesium solution is added at low temperature (-20°) to methylformanilide. After return to room temperature (12h), one observes formation of 2 phases, the lower one being brown. After hydrolysis under acidic conditions (5N SO4 + 200g ice) and usual work up, one obtains piperonal: Yield = 65%.

bp0.5 = 88°; DN24PH mp(acetic acid) = 269° (32b)
Semicarbazone mp (75% ethanol-25% water) = 241°.
Analysis C9H9O3N3: Calc. %: N 20.30
                   Found  :   20.68

3,4-Methylenedioxy-benzoic acid (piperonylic acid)

The carbonation of the magnesium compound is done by adding the latter to crushed dry ice in ether (Dewar). After return to room temperature (12h), the mixture is poured on hydrochloric acid + ice (1/5). After usual work up, the solvents are evaporated and the residue recrystallised in ethanol to give piperonylic acid. Yield = 85%.

mp(ethanol) = 229° (32c)

3,4-methylenedioxy-benzyl alcohol (piperonylic alcohol)

The condensation of the magnesium reagent with trioxymethylene is performed by addition at 40°C. The mixture, kept 2h at this temperature is then heated to reflux and then half of the solvent evaporated. After hydrolysis in alkali conditions and usual work up, piperonylic alcohol (32d) is distilled under nitrogen atmosphere. Yield = 70%
bp0.5 = 98°; mp(petroleum ether) = 55°

1-(3',4'-Methylenedioxy-phenyl)-propan-1-ol (alpha-ethylpiperonylic alcohol)

Prepared by condensation of the magnesium reactant with propanal at 15°. After return to room temperature the solution is refluxed (30min). After hydrolysis under alkali conditions and usual work up, one obtains alpha-ethylpiperonylic acid (32e). Yield = 81%.

bp0.07 = 114°;  nD18 = 1.5413. 		 
 
 
 
    hypo
(Hive Addict)
01-23-03 19:49
No 400896
       part 3/3     

1-(3',4'-Methylenedioxy-phenyl)-prop-1-ene (Isosafrole).

A solution of alpha-ethylpiperonylic alcohol in benzene is heated to reflux with tosic acid (100mg). The water formed is azeotropically removed. After washing with diluted soda solution (5%), followed by usual work up, one obtains isosafrole (32f). Yield = 79%.
bp17=131°; nD20 = 1.5784

4-Methyl-1,2-methylenedioxy-benzene

The organo-magnesium solution is added to boiling dimethyl sulfate. Alkaline hydrolysis and usual treatment gives 4-methyl-1,2-methylenedioxy-benzene (Yield = 78%) (32k):
bp15 = 85°C; nD20 = 1.5314

1-(3'-4'-methylenedioxy-phenyl)-prop-1-ene-3-al (piperonylacroleine)

The organo-magnesium solution is added at -20° to 1-(N-methylphenylamino)-prop-1-ene-3-al (33). A white precipitate forms which quickly turns brown. The mixture is left standing for 1h then heated to 45° (15min). After alkaline hydrolysis, washing the red organic phases with diluted hydrochloric acid and usual work up, one distills and fractionates under nitrogen to obtain piperonylacroleinic acid (32g). Yield = 52%.

bp0.05 = 148°; mp(petroleum ether) = 87°
DN24PH mp(ethanol) = 238° Rf(DMF/Decaline) = 0.21

1-(3',4'-Methylenedioxy-phenyl)-5-carboxy-penta-1,3-diene (piperic acid).

Recrystallised and vacuum dried malonic acid (0,048mol) is added to piperonylacroleine (0.025mol) in dry pyridine (20ml) with a few drops of piperidine; the mixture is heated (1h) on boiling water bath then to reflux. A big amount of yellow precipitate forms which turns red after being poured on a hydrochloric acid / ice mixture (1:8). The precipitate is filtered, sucked dry and recrystallised from alcohol (mp = 248°) then dissolved in acetic anhydride (40ml) and heated to reflux for 30min.  Treatment with cold dilute hydrochloric acid gives a brown precipitate. The latter is redissolved in concentrated ammonia, the solution filtered and piperic acid (32h) precipitated as voluminous yellow precipitate by addition of hydrochloric acid.

Yield = 55%, mp(ethanol) = 218°;
Analysis C12H10O4: Calc. %: C 66.09 H 4.62
                   Found  :   65.80   4.92

Piperine.

Piperic acid (2g) is added under cooling to thionyl chloride (8.5g). It rapidly dissolves, giving a deep red solution. After 45min, the excess thionyl chloride is removed under vacuum. (T < 40°). A small fraction (0.5g) of the red crystals such obtained is recrystallised from benzene and gives piperic acid chloride:

mp(benzene) = 180° (32j).

Piperidine (6ml in 20ml anhydrous benzene) is added to the rest of the crystals dissolved in anhydrous benzene (40ml). The temperature climbs to about 50°C; the solution is left standing for 48h, the formed precipitate filtered off, the solution washed with dilute hydrochloric acid, water, a 10% sodium bicarbonate solution, and finally water. After drying (SO4Na2) the benzene is removed under vacuum, the obtained piperine (32i) crystals recrystallised in alcohol then ether. Yield = 64%.

mp(ether) = 129°

The piperine hydrobromide precipitates quantitatively after addition of benzene saturated with dry hydrobromic acid to a solution of piperine in benzene.

mp(benzene) = 170° (34)

2,2-bis-ethyl-1,3-benzodioxole

Prepared by heating pentan-3-one (0.2mol) in benzene and pyrocatechol (0.2mol) in presence of tosic acid (0.5g) for 24h. The formed water is azeotropically removed. The cooled solution is poured into cold dilute soda solution then extracted using the usual method. Yield = 92%

bp0.1 = 50°; nD19 = 1.5050.
Analysis C11H14O2: Calc. %: C 74.22 H 7.93
                   Found  :   74.73   8.37

DN24PH; mp(ethanol) = 156°; Rf(DMF/Decaline) = 0.8

2,2-bis-ethyl-5-bromo-1,3-benzodioxole

Prepared by reacting N-bromosuccinimide (0.12mol) with 2,2-bis-ethyl-1,3-benzodioxole (0.1mol) in tetrachloromethane at reflux (18h) under UV irradiation in presence of perbenzoic acid. The dark red solution is washed with dilute soda (10%) and after extraction with ether and the usual work up gives 2,2-bis-ethyl-5-bromo-1,3-benzodioxole. Yield = 52%.

bp0.07 = 79°; nD20 = 1.5358
Analysis C11H13O2Br: Calc. %: C 51.40 H 5.10
                     Found  :   51.72   5.40

Reaction with magnesium:

Gilman test: in ether the reaction is violent, but the test turns out negative.
In THF: test positive (violet coloration).
The formation of the organo-magnesium compound is performed in THF using the procedure mentioned before. The reaction proceeds quickly and completely.

2,2-bis-ethyl-5-methyl-1,3-dioxole

The organo-magnesium solution formed using 2,2-bis-ethyl-5-bromo-1,3-benzodioxole in THF is condensed with diethylsulfate with heat. After alkaline hydrolysis and extraction with ether one obtains 2,2-bis-ethyl-5-methyl-1,3-dioxole with a yield of 85%:

bp0.5 = 70°; nD22 = 1.5010.
Analysis C12H16O2: Calc. %: C 75.06 H 8.40
                   Found  :   75.41   8.68
DN24PH mp(ethanol) = 156° Rf (DMF/Decaline) = 0.8

The hydrolysis, performed by refluxing in an equal amount of 20% sulfuric acid for 5h, gives, after extraction with ether 4-methyl-1,2-pyrocatechol. Yield=65%.
bp0.7 = 95°; mp = 64° (32l)

Distillation of the residue at atmospheric pressure allows the isolation of pentan-2-one (32m).

bp760 = 102°; nD20 = 1.3920;

DN24PH mp(ethanol) = 156°.



  
 
 
 
    Rhodium
(Chief Bee)
09-14-03 15:10
No 459028
User Picture  		      Nitrostyrenes to phenethylamines using Al/Hg
(Rated as: good read) 		    

This german article has been partly translated in Post 398546 (hypo: "electrolysis", Novel Discourse) and Post 108476 (dormouse: "Nitrostyrene reduction with Al/Hg...again!  -Sonson", Novel Discourse).

It is very interesting, as it concerns the reduction of nitrostyrenes to phenethylamines using something as simple as aluminum amalgam in acidic solution.

Synthese des 1-(2,3-Dimethoxybenzyl)-5,6-Dimethoxyisochinolins
E. Späth; K. Riedl; G. Kubiczek
Monatsheft 79, 72 (1948) (https://www.rhodium.ws/pdf/ns2pea.acidic.alhg.pdf) 		 
 

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