Uemura has a question. In older times cinnamin acids have been reduced with sodium-amalgane.
Now, can you reduced the double bound using NaBH4? Under standard conditions (i.e. MeOH 0-20DegC)?
Thanks for attention.

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Carpe Diem

I would also be very interested in this. I have also never seen any references to cinnamic acid to hydrocinammic acid using anything else than Na/Hg or catalytic hydrogenation.

Hydrocinnamates are very good starting materials for phenethylamines, using at least three different reaction schemes.

Hi Rhod,
thats why I was asking    Already beesy so early in the morning?

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Carpe Diem

I have also never seen any references to cinnamic acid to hydrocinammic acid using anything else than Na/Hg or catalytic hydrogenation.
Catalytic hydrogenation is so simple and easy that there is no need to look farther - 10% solution of cinnamic acid in ethanol, 1% Adam's catalyst by weight relative to cinnamic acid, room temperature and pressure, hydrogen uptake complete in 8 hours.

adam's catalyst, composition?

Adam's Catalyst (Platinum(IV)Oxide, PtO2)

In a fume cupboard, dissolve chloroplatinic acid (H2PtCl6.6H2O, 0.10 g) in water (ca. 0.5 ml) in a porcelain crucible (3-4 cm diameter). Add sodium nitrate (1 g) and evaporate the mixture to dryness, over a low flame, with continuous stirring. Turn the Bunsen burner full on and stir the contents of the crucible vigorously until the mass has melted completely and the initial decomposition has subsided. Keep the bottom of the crucible at a dull red heat for a further 30 min. (too strong a heat decomposes the oxide to the metal). Allow the crucible to cool and wash the contents into a 250 ml. beaker with hot water from a wash bottle. Filter off the brown platinum oxide with a small ('Hirsch') funnel (Whatman paper No. 541) and wash the oxide with hot water (about 200 ml) until the washings are free from nitrate ion. Dry the catalyst over calcium chloride in a vacuum desiccator.

terbium
Catalytic hydrogenation is so simple and easy that there is no need to look farther
may be fine and efficient. But what if SWIm doesn't have a hydrogen tank or doesn't want to fiddle around with filled hydrogen ballons and if SWIM doesn't have the adam's catalyst and so on. BUT! SWIM may have dozens of grams of NaBH4. Couldn't he use it. Would it bee worth a try?

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Carpe Diem

NaBH4 together with a transition metal catalyst such as CoCl2 or NiCl2 might do the trick if one does some literature digging, but I have no actual references for this handy.

Catalytic transfer hydrogenation of cinnamic acid to hydrocinnamic acid using 10% Pd/C and ammonium formate:

https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000238610-file_utks.gif" title="View this image">

http://www.gac.edu/~ghofmeis/chem51/laboratory/transH.html

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Hydrocinnamates are very good starting materials for phenethylamines, using at least three different reaction schemes.

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Would you care to expound upon this statement, Rhod?

z

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"And if we don't get some cool rules ourselves, pronto, then we'll just be bogus too!"

Check Scheme #9 in

https://www.thevespiary.org/rhodium/Rhodium/chemistry/mda.dalcason.html

If the alpha-methyl group in the cinnamic acid derivative at the top is replaced with a hydrogen (as in standard cinnamic acid), the products of the Schmidt, Curtius or Hofmann reactions will be regular phenethylamines, and not amphetamine derivatives.

Aha, this sounds already better  Thank you Rhod.
Uemura will check next time in the Houben-Weyl and see what he can find in there.

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Carpe Diem

This is a little bit off-topic, but, since you brought it up... are you familiar w/this?:
i found it in another russian book scanned and uploaded by our renowned bibliophil Garin

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"...Addition of nitrogen dioxide dimer to a double bond runs smoothly, if the latter is activated w/a phenylic ring and a carboxyl. E. g., N2O4 adds to cinnamic acid, forming a,b-dinitrohydrocinnamic acid, which upon subsequent detachment of nitrous acid and decarboxylation gives beta-nitrostyrene w/a preparative yield."
https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000238610-file_n9rs.gif" title="View this image">

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Unfortunately, no details or refs were given. Can someone suggest approximate conditions or search in the literature (PolytheneSam, Foxy2, Megamole? ) One more worrisome thing for me is if the ring-subst'd things would survive decarboxylation.

I'm not sure if it's of use - are there any other routes to cinnamic acids then via benzaldehydes?

Antoncho

Antocho,

are there any other routes to cinnamic acids then via benzaldehydes?

The classical way is the Perkinsche Synthesis : benzaldehyde + Acet-anhydride (+ Na-acetate) -> cinnamic acid

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Carpe Diem

Dihydrocinnamic acid can also be formed by condensation of benzyl chloride with diethyl malonate, followed by ester hydrolysis and decarboxylation. Ordinary malonic ester synthesis reaction conditions apply.

Example references: Korean J Med Chem 3, 142 (1993) and Arch Pharm Res 20, 659 (1997)

Check the references in these posts for hydrocinammic acids. 

Post 238027

(PolytheneSam: "Re: Piperonal ---> MDA", Chemistry Discourse)

Post 222968

(PolytheneSam: "Re: The Meerwein Reaction", Serious Chemistry)

>Dimebagoxy......

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http://www.geocities.com/dritte123/PSPF.html

another way from benzaldehydes is to go via the benzalacetones formed from benzaldehyde and aceton by condensation:

Ar-CHO + CH3COCH3 --> Ar-CH=CHCOCH3

next step would be haloform-degradation:

Ar-CH=CHCOCH3 + Hal2 + OH- --> Ar-CH=CHCOO^-
(sorry, no stochiometrics)

hydrogenation can be done already w/ the benzalacetones or with the cinnamic acids. if one uses MEK instead of acetone, one gets upon acidic(!) condensation and after haloform reaction the methylcinnamic acids leading to amphetamines.

otto

otto, you're such a decent bee!

as for my question - yes, i know the main route to cinnanic acids is through the BA's, but are there any other (simpler, possibly) ways? Just curious, though.

Antoncho

Organic Reactions vol. 1 has an amazing overview of the Perkin Reaction including numerous examples of different preparations of cinnamic acid derivatives.  The highest yields reported (80-95%)are generated by reacting a substituted benzaldehyde with an equivalent of malonic acid and an equivalent of pyridine as the base catalyst. 

Malonic acid produces superior yields when compared to acetic anhydride.  The only problem is it's somewhat watched because of its use as a barbiturate precursor.

Example:
3,4-Methylenedioxycinnamic acid
45g. of piperonal(0.3 mole), 60g. of malonic acid (.576mol), 120cc. dry pyridine and 3cc morpholine [Note 1]are heated to the reflux point over a 1 hr period then refluxed an additional 20 minutes.  Rxn. mass is cooled and poured with stirring into a mixture of 175cc conc HCl and 300g chopped ice.  The ppt. is collected via vacuum filtration and washed with 25cc portions of HCl and water.  After drying the ppt. melts at 227-230'C and weighs 49-53g (85-90%)

Note 1:  The original procedure calls for the use of  piperidine.  Morpholine was substituted for this carefully watched amine and yields were identical to those in the citation.

The Willgerodt reaction is also a route to Hydrocinnamic acids:

Reflux a mixture of 53.5 g of propiophenone, 20.5 g. of sulfur and 46 g (46 ml) of morpholine for 6 hours. Pour the reaction product into 400 ml. of 10% alcoholic sodium hydroxide solution and reflux for 7 hours. Distill off the alcohol, dilute with water, acidify with hydrochloric acid, and extract three times with ether. Wash the ether extracts with water, dry, remove the ether and distil. Collect the hydrocinnamic acid at 125-129°C/6 mmHg, it solidifies completely on cooling, mp 46-47°C. The yield is 39 g.

Ref: Vogel, "Practical Organic Chemistry" 3rd Ed, p925