PrimoPyro (Hive Prodigy)
05-08-02 02:56
No 305989
      p-Dicyanobenzene: Photoamination Catalyst....  Bookmark   

.....synthesis revisited. smile

Awhile back, I myself, among others past, had wondered if over the counter p-dichlorobenzene, found in mothballs, could be used to synthesize p-dicyanobenzene, a noted photoamination catalyst, as presented long ago by Drone 342.

The answer was not favorable. The dichloride is very inert to many reagents, and the truth of that matter is that these particular variety of bastard halogens just won't let go of that ring, greedy fucks as they are.

So, it seems that my old thought of using the traditional sodium cyanide halogen swap used for aliphatic chlorides, won't work here. Well, that appeared to be the end of it for some time.

Look what I saw today:
http://themerckindex.chemfinder.com/TheMerckIndex/NameReactions/ONR345.htm

Well, it appears that although sodium cyanide will not swap with aromatic chlorine, but perhaps cuprous cyanide might. I don't know hoew hard it is to prepare this compound (cuprous chloride and sodium cyanide???? extremely doubtful) but maybe CuCN will add on the -CN groups to those positions occupied by the chlorine atoms. 'twoud be neato if it did. smile

p-Dichlorobenzene is dirt cheap and available. I am still pushing the incentive to look hard into this, this catalyst is used to go directly from safrole --> MDMA with zero intermediates! This is but one application! Styrene --> PEA with ammonia's use. The list goes on forever.

                                                PrimoPyro

Vivent Longtemps La Ruche!
 
 
 
 
    Rhodium
(Chief Bee)
05-08-02 08:35
No 306104
      p-dicyanobenzene  Bookmark   

Terephtaldehyde treated with hydroxylamine to form the dioxime, followed by dehydration with acetic anhydride or microwave heating should produce p-dicyanobenzene.
 
 
 
 
    slappy
(Hive Bee)
05-08-02 09:56
No 306133
      Not quite  Bookmark   

CuCN will not substitue aromatic Chlorines. To do that, you would need a homogenous Palladium catalyst or the like. I have talked before about using Zn(CN)2 with Pd(dppf)Cl2 in MeCN/THF or DMF. You can also use KCN, Pd(OAc)2, PPh3and TMEDA in DMF; CuCN and a phase transfer catalyst in MeCN; KCN, NiCl2, PPh3, and Zn powder in THF; CuCN in sulpholane at >200C.

I am still pushing the incentive to look hard into this, this catalyst is used to go directly from safrole --> MDMA with zero intermediates! This is but one application! Styrene --> PEA with ammonia's use. The list goes on forever.

Not quite. I have looked into the matter, and Drone was(like always) full of shit. The yields are not good, and the only reference on the photoamination used 1,1-Diphenylethylene, to give 1,1-Diphenylethylamine, a far cry from our beloved secondary amine. The yields were not good either. There is no compelling reason (yet) to believe that you could go from safrole -hv-> MDMA.

But please, I emplore you to keep trying. Dig up some references, find some good stuff for us, I know you can.
 
 
 
 
    halfapint
(Ubiquitous Precursor Medal Winner)
05-08-02 10:55
No 306155
      Literary Archaeology  Bookmark   

I looked up some old-Hive threads appertaining thereunto, earliest available being a thread Post 102375 (CHEM GUY: "Photo-amination.  A shortcut please!", Chemistry Discourse) marked by discussion of the syntheses of the poisons cyanide, fentanyl, and 3 different nerve gases. Excerpts:

Torch
(Member)
06-25-99 15:28
No 102379
         Re: Photo-amination. A shortcut please!   Reply     

I have no clue about photo-amination but, p-dichlorobenzene is what those toilet mints you aim for in the urinal are mainly comprised of... OTC 'Outta The Commode'




  
    yellium
(Member)
07-24-99 15:52
No 102397
         Re: Photo-amination. A shortcut please!   Reply     

Chemguy: If you would have taken the time to actually go to the library and *READ* the fscking article that's mentioned, you would have noticed that para-dicyanobenzene does catalyze the rx, but also forms unwanted adducts, thus reducing yields & making xtalization more troublesome. m-DCB doesn't have this disadvantage.


and Rev. Drone backed up this assertion, in Post 102391 (rev drone: "Re: Photo-amination.  A shortcut please!", Chemistry Discourse)


What can be used instead of meta-dicyanobenzene (not para, as people continually insist)?


and in Post 102399 (rev drone: "Re: Photo-amination.  A shortcut please!", Chemistry Discourse)


Re: Photo-amination. A shortcut please!   Reply     

Yellium,
Its true enough that p-dicyanobenzene promotes some side reactions (as I've said repeatedly after I wrote that article on Rhodium's page)
...
Also, it doesn't mention anything about Pyrex killing the reaction for a very specific reason: the reaction was performed in a Pyrex vessel, and, to quote a phrase "If you would have taken the time to actually go to the library and *READ* the fscking article that's mentioned", I believe the abstract specifically mentions that the light used was borosilicate (Pyrex) filtered.




In another later thread:


CHEM GUY
(Member)
10-30-99 19:11
No 104616
         Re: Isomerizing dicyanobenzene (phthalodinitrile) from 1,2 to 1,3   Reply     

Forget the DiCynoBenzene route.  Read the patent # 4483757. 
I listed all the parts I thought important in the thread called:-  Homogeneous catalyzed amination of olefins - in the novel discourse forum. 

The advantages for this patent are :
NO DCB
The catalyst is NH4I or NH4Br, or if used in stochimetric amounts, NH4Cl or NH4F
Uses UV light, with a wavelength about 160 nm.
Takes about 4 hours
Uses only the catalyst, olefin, and aminating agent.
Aminating agent is just about anything with minor restrictions that are listed.
MOST OF ALL, IT'S SIMPLE!

Read it, understand it, love it,...

Right rev drone,



rev drone
(Member)
10-31-99 05:50
No 104618
         Re: Isomerizing dicyanobenzene (phthalodinitrile) from 1,2 to 1,3   Reply     

CHEM GUY,
Likewise, I have to say, it sounds just too good to be true. There's got to be a reason M. Yasuda and company chose to use DCB as the catalyst for their reactions, and I'm pretty sure its not because it was on sale.



    Slappy
(Moderator)
11-01-99 22:11
No 104621
         Re: Isomerizing dicyanobenzene (phthalodinitrile) from 1,2 to 1,3   Reply     

Yes. m-DCB is your best bet. Just like Drone said, "meta, meta, meta!".




The only real synthetic contribution for the catalyst is for the debunked para isomer:


Wizard X
(Moderator)
07-07-99 00:23
No 102382
         Re: Photo-amination. A shortcut please!   Reply     

p-dicyanobenzene : start with this compound,
2HNCH2-C6H4-CH2NH2  + P2O5 ==dehydration===>>

NC-C6H4-CN  or C6H4(CN)2




and though I don't believe in the existence of P2O5, never having seen any, there may bee some agency which could perform such a dehydrogenation. If so, I can contribute that m-xylene is the predominant isomer in the can of solvent at the hardware. Dichlorination, by tacking a single chlorine on each of m-xylene's methyl groups, gives m-dichlorodimethyl benzene, or dichloro-m-xylene. These chloromethyl groups could both bee aminated, giving you the preferred meta isomer of WizardX's starting compound above.

Now Slappy sounds discouraging. I was hoping this photocatalyst would prove the magic bullet. I got unsatisfactory results using ammonium bromide catalyst, though my test rxn conditions were not very rigorous, and the mercury-catalyzed photoamination isn't very appealing. It's still up in the air, far as I'm concerned.


a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.
 
 
 
 
    Antoncho
(Official Hive Translator)
05-08-02 11:27
No 306160
      !!!  Bookmark   

Excellent, Half-A-Pint, was very interesting to read.

Personally i believe there must bee some hidden diamond in one of these routes....someday....


Antoncho
 
 
 
 
    Osmium
(Stoni's sexual toy)
05-08-02 13:24
No 306199
      > p-dicyanobenzene : start with this compound, ...  Bookmark   

> p-dicyanobenzene : start with this compound,
> 2HNCH2-C6H4-CH2NH2  + P2O5 ==dehydration===>>
> NC-C6H4-CN  or C6H4(CN)2

There's a typo, it should be:

2HNCO-C6H4-CONH2 + P2O5 ==dehydration===>>

P2O5 is a very common chemical. This reaction is a dehydration, not a dehydrogenation!


I'm not fat just horizontally disproportionate.