04-19-00 13:35
No 122761
      propenyl benzenes -> amphetamines in one step -drone 342
(Rated as: good read)

Author  Topic:   propenyl benzenes -> amphetamines in one step 
drone 342
Member   posted 10-19-98 05:23 PM          
I haven't looked these ones up yet, but doesn't the concept capture the imagination?
-drone #342


Reaction ID 2023972
Reactant BRN 1911285 1,2-dimethoxy-4-trans-propenyl-benzene
Product BRN 1639698 2-<3,4-dimethoxy-phenyl>-1-methyl-ethylamine

Reaction Details 1 of 2

Reaction Classification Preparation
Reagent ammonia, 1,3,5-triphenylbenzene (TPB), m-dicyanobenzene (m-DCB)
Solvent acetonitrile
Yield 65. (BRN1639698)
Other conditions Irradiation
Ref. 1 5808890; Journal; Yamashita, Toshiaki; Yasuda, Masahide; Isami, Toshihiro; Nakano, Shozo; Tanabe, Kimiko; Shima, Kansuke; TELEAY; Tetrahedron Lett.; EN; 34; 32; 1993; 5131-5134;

Reaction Details 2 of 2

Reaction Classification Preparation
Reagent m-dicyanobenzene, NH3, 1,3,5-triphenylbenzene
Solvent acetonitrile
Time 18 hour(s)
Yield 65. (BRN1639698)
Other conditions Irradiation
Ref. 1 5903148; Journal; Yamashita, Toshiaki; Yasuda, Masahide; Isami, Toshihiro; Tanabe, Kimiko; Shima, Kensuke; TETRAB; Tetrahedron; EN; 50; 31; 1994; 9275-9286;

drone 342
Member   posted 10-19-98 07:27 PM          
GodDAMN, sometimes I impress myself!
I think everybody is able to see (or at least convice themselves with a little suspended disbelieve) the problem with direct amination across a double bond. Sure, thermodynamically its possible, but the energy barrier is pretty high, which means a big mess. Well, I have the ref's I listed in the last post sitting in front of me, and these wacky Japanese researchers have "DREAMED THE IMPOSSIBLE DREAM" - they managed to aminate IN A SINGLE STEP using:

1) propenyl benzenes as starting material(isosafrole should work)

2) acetonitrile:H2O (9:1) as solvent.

3) dicyanobenzne as a catalyst (cheap)

4) ammonia

5) a little light (high pressure mercury vapor lamp.)

Ambient temperature and pressure!!! Can you friggin' stand it?! I have an extensive list of similar reactions done by the same fellows, as well as the original articles themselves, with all their photoinduced nulceophilic addition reactions.


-drone #342

drone 342
Member   posted 10-19-98 07:47 PM          
Here's a little Current Contents search on photomamination: a word worth remembering.
Ovid Technologies, Inc. Email Service

Workentin MS. Parker VD. Morkin TL. Wayner DDM.
Journal of Physical Chemistry. 102(32):6503-6512, 1998 Aug 6.
Radical cations of 9-aryl- and 9,10-diarylanthracenes with substituents on
the 4 position of the aryl rings (PA-X.+ and DPA-X.+, respectively) have been
generated by photoionization in acetonitrile. Their reactivity with
n-butylamine (n-BuNH2) and 1,4-diazabicyclo[2.2.2]octane (DABCO) and a number
of anions (CH3CO2-, Br-, CN-, N-3(-)) has been studied using nanosecond laser
flash photolysis. Reactions proceed by electron transfer and/or nucleophilic
addition. Using PA-X and DPA-X as chemical probes, simple criteria are
established that allow one mechanistic pathway to be distinguished from
another. When electron transfer is thermodynamically feasible, this pathway
dominates (e.g., DABCO and azide). For endothermic electron transfer,
addition is not necessarily the preferred ultimate reaction pathway and an
inner sphere process (addition/homolysis) can compete. In these cases other,
criteria including steric factors and the strength of the incipient bond
become important. Simple kinetic criteria and an approach to estimate the
thermochemistry of the addition process are developed. It is clear from these
studies that reactivity trends in the radical cation chemistry cannot be
generalized as easily as those in carbocation chemistry. This has some
implications concerning the development and utility of ''clock'' reactions in
radical cation chemistry. [References: 79]

Yasuda M. Kojima R. Ohira R. Shiragami T. Shima K.
Bulletin of the Chemical Society of Japan. 71(7):1655-1660, 1998 Jul.
The photoamination of 1-(2-methyl-1-propenyl)naphthalene
(1a) with ammonia in the presence of p-dicyanobenzene (p-DCB) occurred
selectively at the alkenyl group but not at the naphthyl group to give
1-(2-amino-2-methylpropyl)naphthalene (2a). Similarly, the
photoamination of several kinds of alkenylnaphthalenes (1)
proceeded selectively at the alkenyl group. The
photoamination proceeded via the nucleophilic addition of
ammonia to the cation radical of 1 generated by the photoinduced electron
transfer to p-DCB to give the aminated radical after deprotonation.
Distribution of the positive charge in 1(+.) and the stabilities of the
aminated radicals were calculated by the PM3-UHF method. The stabilities of
the aminated radicals agreed with the regioselectivity. [References: 43]

Kojima R. Shiragami T. Shima K. Yasuda M. Majima T.
Chemistry Letters. (12):1241-1242, 1997.
Photoamination of 1,2-distyrylbenzene (la) with NH3 in the
presence of p-dicyanobenzene has been investigated.
1-Benzyl-3-phenyl-1,2,3,4-tetrahydroisoquinoline (2a) and
1-amino-3-benzyl-2-phenylindan (3a) were formed as a consequence of the
nucluophilic additions of NH3 to 1a(+.) and indan-type cation radical (4(+.))
generated by transformation of 1a(+.). [References: 18]

Kojima R. Yamashita T. Tanabe K. Shiragami T. Yasuda M. Shima K.
Journal of the Chemical Society. Perkin Transactions 1. (3):217-222, 1997
Feb 7.
The photoamination of 1-arylalka-1,3-dienes 1a-f and
1-aryl-4-phenylbuta-1,3-dienes 1g-k with NH3 in the presence of
p-dicyanobenzene (DCB) gives 4-amino-1-arylalk-2-enes 2a-f and
1-amino-1,4-diarylbut-2-enes 2g-k, respectively, The
photoamination proceeds by nucleophilic addition of NH3 to
the cation radicals of 1(+.) generated by photoinduced electron transfer to
DCB, The regiochemistry of 2 is related to the distribution of the positive
charge in 1(+.) calculated by the PM3-UHF/RHF method, the stability of the
aminated radicals formed by the addition of NH3 to 1(+.) and the stability of
the aminated anion formed by the reduction of the aminated radicals by DCB-..
The stabilities of these intermediates are estimated by the calculation of
the heat of formation by the PM3-UHF/RHF method, Distributions of the
positive charge in 1(+.) and the stabilities of the aminated anion show a
good agreement with the product analysis. [References: 24]

Yasuda M. Yamashita T. Kojima R. Shima K.
Heterocycles. 43(11):2513-2522, 1996 Nov 1.
This paper reviews the recent author's studies on the
photoamination via electron transfer which were applied to
the introduction of the amino group to C-C double bonds of several kinds of
the substrates involving arenes, stilbenes, and benzo[a,d]cycloalkenes. The
aminated products were used as the precursors for the synthesis of the
heterocyclic compounds involving benzylisoquinolines, aporphines, isopavines,
dibenzo[a,d]cycloheptenimines, and oxazepines. [References: 55]

Yasuda M. Wakisaka T. Kojima R. Tanabe K. Shima K.
Bulletin of the Chemical Society of Japan. 68(11):3169-3173, 1995 Nov.
The photoadditions of ammonia and alkylamines (RNH(2)) to 5-hydroxy- and
5-alkoxy-5H-dibenzo[a, d] cycloheptene derivatives (2) occurred at the
C10-C11 double bond upon the irradiation of 2 with RNH(2) in the presence of
p-dicyanobenzene. The resulting 5-substituted
10-alkylamino-10,11-dihydro-5H-dibenzo[a, d]cycloheptenes were converted to
5-substituted N-alkyl-10,11-dihydro-5H-dibenzo[a, d]cyclohepten-5,10-imines
by a treatment with AcOH. [References: 17]

Shishkina RP. Sergienko NV.
Russian Chemical Bulletin. 43(12):2083-2086, 1994 Dec.
5- and 8-Amino-2-phenylnaphtho[2,3-d]-1,3-thiazole-4,9-diones were obtained
by treatment of 3,5-diamino-2-chloro- and 2,5
-diamino-3-chloro-1,4-naphthoquinones with sodium sulfide followed by
condensation with benzaldehyde. Thermal and photochemical butylamination and
CoCl2-promoted arylamination of 5-amino-2-phenylnaphthothiazole-4,9-dione in
position 8 was carried out. [References: 15]

Yasuda M. Sone T. Tanabe K. Shima K.
Journal of the Chemical Society. Perkin Transactions 1. (4):459-464, 1995
Feb 21.
Irradiation of o-alkenylphenols 1a-e and 2a-e in the presence of alkylamines
gave o-(1-alkylaminoalkyl)phenols 4a-n and 5a-e in relatively good yields.
Deprotonation of these o-alkenylphenols by the amines occurs in the excited
singlet state to give the excited singlet state of the phenolate anion 7 and
the ammonium ion. The proton transfer from the ammonium ion to the alkenyl
group of 7 generates the zwitterion 8 that allows the nucleophilic addition
of the amine at the benzylic cation centre. Similar
photoamination of 1-(2-methylpropenyl)-2-naphthol 3 with
alkylamines occurred to give 1-(1-alkylamino-2-methylpropyl)-2-naphthols
6a-b. [References: 11]

Workentin MS. Johnston LJ. Wayner DDM. Parker VD.
Journal of the American Chemical Society. 116(18):8279-8287, 1994 Sep 7.
Rate constants were measured for the reactions of 9-phenylanthracene (PA) and
9,10-diphenylanthracene (DPA) radical cations with a number of primary,
secondary, and tertiary amines in acetonitrile using nanosecond laser flash
photolysis (NLFP), Generation of the radical cations of PA and DPA (PA(.+)
and DPA(.+)) was accomplished by 266- or 355-nm photoionization of the parent
compound. Primary amines react with PA(.+) with second-order rate constants
in the range 8 X 10(6) to 2 X 10(9) M(-1) s(-1), and rate constants for
reaction of DPA(.+) with the same amines are 60-250 times lower. For both
radical cations, Bronsted-type plots of log(k(amine)(RNH(2))) versus
pK(a)(RNH(3)(+)) serve to illustrate that the rates of reaction with primary
amines increase with increasing amine basicity and decrease as the steric
requirement of the amine increases. Transient absorption studies complement
the kinetic data and demonstrate that primary amines react with both radical
cation species by nucleophilic addition to generate the expected radical
intermediates. The observed difference in reactivity between PA(.+) and
DPA(.+) with these nucleophiles can be accounted for by the lack of steric
hindrance toward nucleophilic attack at the 10 position in the former. In
acetonitrile/water (9:1) solution, rates of reaction with the primary amines
are retarded compared to those in acetonitrile and the extent to which the
rates are slowed is largest for the more basic amines. It is suggested that
the rate differences observed in the mixed solvent system are a result of the
equilibrium between free and hydrated amine. Interestingly, the reactivity
patterns for the addition of primary amines to these radical cations parallel
those observed in carbocation chemistry. Tertiary amines and anilines were
found to react with both radical cation species with similar rate constants,
exclusively by electron transfer, regenerating PA or DPA concomitant with
formation of the radical cation of the corresponding amine. Rate constants
for reaction with tertiary amines range from 1.5 X 10(9) M(-1) s(-1) to rates
approaching the diffusion-controlled limit in this solvent (2 X 10(10) M(-1)
s(-1)) and correlate with the oxidation potential of the amines. Secondary
amines exhibit rate constants that do not reflect their basicity. For PA(.+),
electron transfer occurs competitively with nucleophilic addition and, thus,
the rate constants measured reflect the relative contribution from each of
these two processes. Nucleophilic addition to DPA(.+) is in most cases slow
enough that electron transfer dominates. [References: 82]

Yamashita T. Yasuda M. Isami T. Tanabe K. Shima K.
Tetrahedron. 50(31):9275-9286, 1994 Aug 1.
The photoaminations of trans-1-arylpropenes (aryl =
2-methoxyphenyl (1), 3-methoxyphenyl (2), 3,4-dimethoxyphenyl (3), and
4-methoxyphenyl (4)) with NH3, i-PrNH2, and t-BuNH(2) (RNH(2)) in the
presence of p-dicyanobenzene (p-DCB) gave 2-alkylamino-1-arylpropanes (9)
and/or 2-alkylamino-1-aryl-1-(4-cyanophenyl)propanes (10). The
photoaminations of 1,2-dihydro-7-methoxynaphthalenes (6-8)
with RNH(2) in the presence of p-DCB gave mainly
2-alkylamino-1-(4-cyanophenyl)-6-methoxy-1,2,3,4-tetrahydronaphthalenes (13).
The photoamination of trans-1-(3,5-dimethoxyphenyl)propene
(5) with i-PrNH2 occurred at aromatic ring to give
trans-1-(2-isopropylamino-3,5-dimethoxyphenyl)propene (11). The
photoaminations of 1-4 and 6-8 with NH3 in the presence of
m-dicyanobenzene gave the aminated products without incorporation of
cyanophenyl group. Furthermore, the addition of 1,3,5-triphenylbenzene and
m-terphenyl for these reactions improved the yields of the photoaminated
products. [References: 46]

Yasuda M. Watanabe Y. Tanabe K. Shima K.
Journal of Photochemistry & Photobiology A-Chemistry. 79(1-2):61-65, 1994
Apr 10.
Photoaminations of several methoxy-substituted phenanthrenes
(ArH) with ammonia in the presence of m-dicyanobenzene (A) were investigated.
The photoamination of 2-methoxyphenanthrene (1a) and
3-methoxyphenanthrene (1b) gave 1-amino-2-methoxy-1,4-dihydrophenanthrene
(2a) and 9-amino-3-methoxy-9,10-dihydrophenanthrene (2b) respectively. The
photoamination of 3,6-dimethoxyphenanthrene (1c) gave
9-amino-3,6-dimethoxy-9,10-dihydrophenanthrene (2c), while no
photoamination of 2,3-dimethoxyphenanthrene (1d) and
2,3,4-trimethoxyphenanthrene (1e) occurred. The
photoamination proceeds via the nucleophilic addition of
ammonia to the cation radicals of ArH (ArH.+) generated by the photochemical
electron transfer to A. Therefore the regiochemistry on
photoamination is related to the distribution of the
positive charge in ArH.+. In order to compare the reactivity of the cation
radical of 9-methoxyphenanthrene (1f) with that of parent phenanthrene, the
rate constant for nucleophilic addition to the cation radical of If was
determined by kinetic analysis. [References: 22]

Yamashita T. Tanabe K. Yamano K. Yasuda M. Shima K.
Bulletin of the Chemical Society of Japan. 67(1):246-250, 1994 Jan.
Photoaminations of 2-alkoxynaphthalenes (1) with ammonia and
primary alkylamines were performed by irradiating an acetonitrile-water
solution containing 1, an amine, and m-dicyanobenzene to give
1-alkylamino-2-alkoxy-1,4-dihydronaphthalene (2) in relatively good yields.
The conversion of 2 to N-acetyl-1-alkylamino-2-tetralones was performed by
acetylation with Ac2O followed by a treatment with BF3.OEt(2). [References:

Member   posted 10-20-98 09:54 AM          
Once again brought to you by Drone 342! Thanks! Lr/
drone 342
Member   posted 10-20-98 06:58 PM          
Simply out of sheer saltiness (due to the most recent snubbing that my contribution has endured), I wish to report that the apparatii used in Tet 50,31,9275-9286(1994), and in Tet. Lett. 34,32,5131-5134(1993), both implement high-presure mercury bulbs as their light source -- thus further establishing this method's general usefulness to clandestine chemistry.
still quite indignant over the whole matter,

-drone #342

drone 342
Member   posted 10-20-98 07:24 PM          
A couple people have e-mailed me, requesting information on the specifics of the lamp used in these experiments. Its an Eikosha PIH-300 high-pressure mercury lamp.
-drone #342

Member   posted 10-22-98 10:53 AM          
Drone, can you tell me which wavelength of light this lamp will emit? That's very important for the reaction, since the light is a "reagent" here.
And what do they mean with "a pyrex filter under water cooling"? Do they simply put a pyrex bowl full of water between the lamp and the reaction flask or something? That's how we did the watercooling when doing photochemistry. Lr/

drone 342
Member   posted 10-22-98 12:38 PM          
Exactly. "Pyrex Filter" refers to the fact that the light emitd from the mercury vapor traveled through the reactor vessel, thus fitlered by the pyrex. This means all wavelengths abosrbed by borosilicate glass (not too many), were eliminated.

Mercury vapor bulbs emit a wide spectrum of wavelengths, and there's really nothing too special about them -- I'm sure even MH should work, probobly better since it doesn't get as hot. Check out the hydroponic web pages to get a full description of the spectra of these lights. Essentially, all these guys used was a mere marijuana grow light (at least, that's what we use 300 W mercury vapor lamps for in my neighborhood!) I'm sure there are more than a few people on The Hive that have one or two of those laying around.

Though I don't know off the top of my head what discrete bands of wavelengths are needed, this could be quickly figured out by looking at the absorption spectra for m-DCB. Something readily obtainable for anyone with library access and a understanding of how to use it. Regardless, all that's needed is a good strong lightbuld with a spectrum roughly covering the needed band -- any number of differnt bulbs and different styles of bulbs should do the job.

The other place to look might in the list of references I gave, specifically Journal of Physical Chemistry. 102(32):6503-6512, 1998 Aug 6. There's an article that describes the use of a nanosecond puls laser. Since this reaction did what were're interested in, and since lasers emit s discrete wavelength of coherent light, from there one can deduce the wavelength requirements of this reaction.

Watercooling is exactly how you describe it. Really, there's absolutely nothing fancy about this reaction, except how terribly stylish it is!

-drone #342

Member   posted 10-23-98 10:01 AM          
I have to admit, this is one classy reaction! Dr. Shulgin speculated in PIHKAL on a theoretical addition of ammonia on certain essential oil components, but he probably had no idea how to do this in practice. Well, some Japanese guys came and did it! With light! This is such exciting stuff!
But there are a couple of things that need some attention. For example, how are we going to recycle that m-DCB and 1,3,5-TPB? The authors acetylate the reaction products and then chromatograph it. This is not practical on a preparative scale. m-DCB can probably be distilled under reduced pressure, but 1,3,5-TPB will have a very high boiling point. Luckily it's a stable molecule. If you some good ideas on how to recycle these components, let me know.

Working with nanosecond puls-lasers? Interesting, but that's in my opinion a little to professional! Let's keep it simple, shall we! I like the mercury vapor lamp idea.

You still use mercury lamps for maryjane farming? In Holland we use high-pressure sodium lamps for that (400 or 1000 W). The mercury vapor lamps give off more blue light, which is better for growing the maryjane, but not for the flowering. You need more red light to get the biggest buds. The sodium lamps emit much red light and some blue light to make'em grow. So the sodium lamps are the best choice for ganja farming.

Next week the topic is indoor hydroponic systems. Lr/

04-19-00 13:38
No 122762
      Re: propenyl benzenes -> amphetamines in one step -drone 342  Bookmark   

drone 342
Member   posted 10-23-98 10:45 AM          
We currently use MH as well; but the mercury vapor lamps are readily available. Say, do you think you might be able to find a comparative spectral-output-diagram-thingie for the various types of bulbs? I've just gotten done with about four days of mad library strip-mining, and if I have to look up another thing today, I swear I will go nuts.
Speaking of which, I need to make a correction or two. m-DCB is not as good a catalyst as p-DCB, and the energy needed to excite the electrons in a cyano group is 10.14 eV -- which if I remeber correctly is pretty high (meaning a rather short wavelength.) This number can be readily converted into the wavelength of light required somehow, but I can remember exactly the formula. I want to say DeBroglie, but I could be wrong. Its been a while since I studied quantum mechanics, so if you could be so kind, Lr, I'm sure you've studied it as well -- you just have that aura about you.

The way I forsee separation is quite simple -- acid-base extraction. DCB and TPB are both very hydrophobic, and MDMA is quite hydrophilic in the right circumstances. Simply strip off the acetonitrile in vacuo, then extract the residue with DCM, and extract the DCM solution with a few washings of diluted HCl. From there, the DCB and TPB can be purified by fractional distillation under reduced pressure, and the MDMA by means of acid-base extraction and subsequent distillation. I've never used the term before, but I think its safe enough to use in this case: badda-bing, badda boom.

Sure, TPB has a high bp, but its not too unmanagably high at, say, 30 torr. You're absolutely right in saying its a stable compound. If you want, I can send you a Beistein review of all the basic chemical properties of all the components avaiable. Actually, if you visit my web page, I'm workingon an informational page about this reaction.

Let me know if you have any more good thoughts on this stuff, and how I might be able to help out. I think this is one of the most exciting discoveries by any Hive bee yet (if I do say so myself), and I think that I'd be great if its developement was an international effort.

-drone #342

drone 342
Member   posted 10-23-98 10:49 AM          
< A HREF = "" > This is a break-down of some useful data on p-DCB.< /A > If the link I tried to insert didn't work, the url is:

-drone #342

drone 342
Member   posted 10-23-98 02:11 PM          
I did the calculations, and I came up with a wavelength of around 123 nm from that 10.14eV, which puts it squarely into the far end of the UV spectrum (if that's not an oxymoron.) Here's how I came up with it:
If E = 10.14 eV,


1 eV = 1.6022 E(-19) J

h = 6.62608 E(-34) J s

c = 2.99792 E(8) m/s

E = h v (that should be a "nu", but I think you get the idea)

c = l v (that should read "lambda nu", but again, y'know what I mean; the speed of light equals the frequency times the wavelength)

v = E / h
l = c / v


l = c h / E

...Which I got to be 123 nm, which is right in the ballpark for a quantum transition of bonding electrons (what's happeining in our little reaction.)

Anywho, gettin' back to the matter at hand, aside from being really confusing, this really doesn't mean a whole lot (though I'm sure everybody figured that out for themselves.) Other frequencies should work, including frequencies a little lower and a little higher than 123 nm (this due to the Doppler effect, etc.), not to mention frequencies that might activate it to other equally useful excited states.

What this *does* tell us is a confirmation of what I said before. For maximum results, we want a light source with a spectrum on the high-end of energy -- more blue than red. Acordinf to waht you said, mercury vapor lamps may be more preferable to sodium, but what of other light sources? And what of the whole heat vs. intensity of useable photons deal? I'll leave the rest up to you.

-drone #342

Junior Member   posted 10-23-98 03:47 PM          
Alright! For the past couple of months I have been researching methods for direct amination of alkenes. I found a bunch of promising routes. The one that seems most promising is... photoamination (in my humble opinion)!
Most first exposure to the process came in the form of US patents #4483757 and 4459191. They used actinic light(UV) and a photococatalyst, an amine and an alkene. Their yields were only 20% and I kind of last faith in the possibility of photoamination of isosafrole. But in steps the Japenese researchers and their amazing advances in photoamination.

Now regarding the source of light...Drone you calcaulated around 128nm. I don't think this is right, it wouldn't make it through the glass. The patent the discuss the ideal types of lamps and glass to conduct the reactions in. It seems that conventional quartz glass(Pyrex) has a cut off around 180nm. Silica glass lets +160nm through.
I wonder what the absorbing properties of plastic are? I think that the absorb short-wave length radiation very well.

Of course the wavelength that is required to excite the catalysts we are talking about is different. It seems that is a higher wavelength since mercury lamps are used very effectively.

Anyway, deuterium lamps, low pressure mercury argon lamps, and high energy xenon flash lamps emit in the range of 160-200nm. High pressure mercury lamps produce emissions in the higher spectrum, 200 to 1400nm.

I feel that this reaction has a huge potential to scale up. One would have to have a lot more catalyst, longer stirring times (who cares!) and possibily a stronger output (more watts).

Oh,by the way, there have been aminations of methylene dioxy derivatives. See JOC vol 57, no 5, 1992, p. 1351. The yields for these compunds sucked (20%). But, the improvements in Tet, vol 50, no 31 pp.9275 using better catalysts,to similar compounds were up to 65-91% I would expect our friend to be around 65%. What do you think Drone?

Now where can I get that m-DCB and some yummy TPB?


Member   posted 10-24-98 08:48 AM          
You want a spectral energy distribution of the lamps? I could only find one for the sodium lamp. It's in "Marihuana binnen" by Jorge Cervantes (Dutch version, how do you like that for a ref?!). I can send it to ya if you like.
The separation of m-DCB and TPB you're giving looks good and is certainly workable. You're composing a whole web-page on this subject? I'll go check it out as soon as it's ready!

The calculation you did was correct, but I agree with Icculus that normal glass will absorb all of the light in the frequency you gave. Maybe we need the ionisation potential
of yet another transition. I reread the TET article and found the authors found 300 nm important, since they did measuremeants in at this wavelength. This seems more logical to me, since the high-pressure mercury lamp will emit in this range. Lr/

drone 342
Member   posted 10-24-98 11:08 AM          
...And that's the confusing part! Obviusly, there's something missing here.
The amount of energy required for electron dissociation from DCB (photoionization) has been measured at 10.14 eV by several different ref's. Doing all the caluculations as shown, you get 123 nm, which I agree is a very high-energy wave, and if borosilicate (Pyrex(tm)) glass (which incidentally is a different animal than quartz), will absorb that frequency, then how is is that this reaction takes place with pyrex-filtered light? What's going on, and can anyone explain why 300nm works?

300 nm is a number I could come to believe; its still pairly short, but why would it work? How does this work? According to the Japanese research aforementioned, the mechanism for this clearly involves photoionization, but 300 nm, in theory, *shouldn't* do it.

Icculus, many thanks for the new ref's and the added background. What are the conditions used in those ref's you described? What catalysts have worked/failed for this?

Obviosly, you've done some homework in this subject. Have you any comparative literature with hard data on the spectral energy distribution of various possibly useful lamps?

DCB is used extensively, I am told, in semiconductors and other electronics. The stuf is cheap and readily available -- Acros sells the stuff for around 77 USD/kg. TPB is a little harder to come by; the stuff is rather carcinogenic, though still it ain't too pricey. Many other (cheaper) sources exist for both, but that the only one to come to mind right now.

-drone #342

drone 342
Member   posted 10-26-98 05:44 PM          
I looked up those ref's, but one of them was one of the original articles I cited.

The other one was more interesting though. In JOC vol 57, no 5, 1992, p. 1351, they do indeed describe the use of a methyledioxy-containing material, and they do get bad yeilds, but there are some discrepancies here. First, they use the same catalyst here as they did in the Tetrahedron article, so that isn't what accounts for the low yield. Secondly, they use stilbenes instead of methylstyrenes, getting lower yields consistantly, with a couple exceptions. The thing that seems to be a big factor in that reaction is the solvent ratios; they got the best yeilds with a 7:2:1 ratio of acetonitrile, benzene, and water ( actually, a mixture of 9:0:1 seemed to work well too.)

Anyways, what we really need some hard data on spectral output of incandescent lights.

-drone #342

Junior Member   posted 10-30-98 02:22 PM          
Photoamination of Isosafrole:
Mechanism of reaction : The photoamination of isosafrole is initiated by electron transfer from the excited singlet state of isosafrole to DCB. The Isosafrole (I) is excited by the light much more than the DCB; the molar excitation coefficient at 300 nm for the styrene derivative is 7x10^3 versus 43 for p-DCB. So, this forms cation radicals of I and anion radicals of DCB. Addition of RNH2 to I gives the aminated radical after deprotonation. The one electron reduction of the I aminated radical with the DCB anion radical followed by protonation gives the aminated products.

The wavelength calculated for exciting DCB was right, but we aren't trying to excite the DCB. Photocatalysis is so effective because molecules are excited at different wavelengths. Using light filters (like Pyrex, which lets 90% of 360nm, 50% of 300nm and 20% of 290 nm light through) allows one to selectively excite certain molecules.

Light Source:
In the original articles (see above) a high pressure mercury lamp is used because it has a high discharge around 300nm through about 450 nm. By using Pyrex and acetonitrile as the solvent ( which transmits 100% of 313nm and 10% 190nm) the light that reaches the solution is high in 300nm radiation, which effectively excites our molecule.

Metal Halide lights are the same as Mercury lamps except that they also conatin a halide (of course!), This broadens the specturm of light to make it more like sunlight. Therefore a Metal Halide would work just as well, if not better. Most hardware stores sell mercury lamps and metal halides.

Methodology for Photoamination:

Degassing of Solvent:
It is very important that the solvent is free of impurities such as air and peroxides. This is easily accomplished by bubbling an inert gas, such as nitrogen, argon or helium through the solvent. Nitrogen is readily available but still contains some water and oxygen. Helium is readily available and is the best choice.

Aparatus for Reaction.

In classical organic photchemistry, an immersion well is used, where the reaction solution surrounds the lamp or an external radiation method where the reaction solution is surrounded by a battery of lamps.

To see an imersion well click here:

An immersion well would be ideal, they can range in size from 100ml to a few litres. It may be possible to obtain one but the exteranl-irradiation method is more applicable:

The solution is in a Pyrex flask and placed in the center of a battery of lamps. Typically a quartz flask is used, which allows 200 nm and above through. For our purposes, the flask itself acts as the filter. Fans can be used to control the temperature. One lamp with mirrors surrounding the flask may be sufficient for
our purposes.

Amine source:

Ammonia or methylamie can be bubbled into the acetonitrile. Or methylamine gas can be produced and liquified by venting into a flask in a ice/salt bath. This can then be directly added to the solution.


Into a Pyrex vessel is introduced an MeCN (70 ml) solution containing isosafrole (3.5 mmol) , m-DCB(3.5 mmol), TPB(0.75 mol), bubbled with helium gas, and then an amine (17.5 mmol) was added to the solution. Solution is irradiated for an appropriate time (18 hr) with a high-pressure mercury lamp or metal halide (300W or more). Solvent is evaporated and products are seperated by column chromatography or most likely extracted with HCL solution, washed with DCM, basified and extracted with DCM.

This reaction can be scaled up, the key is getting sufficient irradiation of the solution.

I hope this information is helpful in answering some questions reagarding this amazing reaction.

Information on the spectrum of lights and techniques of photocatalysis can be found in the book Best Synthetic Methods: Photochemical Synthesis by I. Ninomiya and T.Naito.,1989

Other good reading:
W.M. Horspool , Synthetic Organic Photochemistry, 1984

A.Schonberg, Preparative Oranic Photochemistry, 1968

drone 342
Member   posted 11-03-98 09:42 AM          
Many thanks for the in-depth information on this reaction. However, I do still have a couple questions. What is meant by "pyrex and actenitrile transmits 100% at 313 nm, and 10% at 190nm"? The 100% I can understand, but how does this 10% number fit in with Beer's law, where transmission is dictated by A=Ebc?
Another question is regarding procedure. If one looks at the molar concentration, one has to think that this must be boostable, but to what degree? If it could be raised by an order of magnitude, this would be an extremely amazing procedure.

This is obviously a minor question, since you've really done a swell job of collecting a ungodly amount of good, hard data. This really looks like a winner. Great job, Icculus!

-drone #342

Junior Member   posted 11-03-98 05:21 PM          
Thanks. I'm trying my hardest to perfect this reaction. Maybe I should call those original researchers; we could all do lunch and talk about the miracles of photoinduced electron transfer.
When light hits an object/surface/liquid/gas it can do a number of things. Scattered, defracted, absroberd, transmitted,etc. So light can be transmitted at varying degrees, like most things, nothing is always a hundred percent. So when 290nm hits pyrex only 20% of it makes it through. The rest is abosrbed or reflected.

Early you said that p-DCB was a better catalyst than m-DCB. Why? I don't think so, from what I've read.

Scaling. That is the biggest question right now. The problem with using external irradiation, like we are proposing, is that light isn't transmitted as well as using an immersion-well. I thnik that using a large flask, with a large surface area and possibly multiple lights, it can easliy be scaled up to industrial quantities.

I found a reference on scaling photocatalized reactions, but we don't have the book at my library. It is in Ullmann's Encylopedia of Industrial Chemistry. There is a section on photoreactions, reactos and such. Should be very helpful. Maybe you can find it. I think we would all appreciate it in the long run!

Oh yeah, I also found an old article: J. Assoc. Off. Anal. Chem, vol.61, no. 4, 1978 , p.951. They were analyzing a horrible, naughty illegal manufacturing lab. Anyway, the max UV absorbance of isosafrole is 260-304nm. What a coincidence! And we have a readily avalible source of light with great output in that range. In fact I think I'll go buy one at the Depot, right now>


Member   posted 11-04-98 05:24 AM          
Give me that Ullmann ref. I think I can get it.
Junior Member   posted 11-04-98 09:04 AM          
Go to the Wiley-Vch web and look under photochemistry and reactor types.
It has the entire table of contents but that's it.
The full title is Ullmann's Encylopedia of Industrial Chemistry, 6th Ed., 1998, Electronic Release. The whole thing is on CDRom now. My library doesn't have a copy. Earlier paper editions may have the info, but I don't know.

drone 342
Member   posted 11-04-98 03:31 PM          
I'm sitting here with a copy of Ullmann's Encyclopedia of Industrial Chemistry, volume A 19 in front of me. Nice. Very nice. The photochemistry section is 24 pages of rockem'-sockem' chemistry excitement, complete with schematics of industrial-scale reactors. Have no fear, oh less-priveledged chemists; drone #342 will scan a copy of everything onto his website soon.
-drone #342