blondie (Stranger)
01-25-02 23:26
No 261028
      HCN, NaOH and BzCN  Bookmark   

swim is looking at the possibility of preparing an aqueous solution of KCN by bubbling HCN into NaOH (from H2SO4 + K ferrocyanide) ../rhodium/chemistry /nacn.txt

His question is how to obtain a neutral aqueous solution of NaCN? (risk of liberating free HCN)

alternatively if a still basic solution of NaCN (excess NaOH remaining) was used in the benzyl cyanide synth ../rhodium/chemistry /benzylcyanide.html, would this be a problem? if some of the benzyl chloride reacted (immediately?) with the NaOH this might only affect yields.

also see Post 76846 (Bwiti: "Sodium Cyanide", Chemistry Discourse) Bwiti asked a similar question.
 
 
 
 
    Osmium
(Stoni's sexual toy)
01-26-02 14:43
No 261235
      Re: HCN, NaOH and BzCN  Bookmark   

Before you try anything like that you have to learn the basics.
For example that NaCN dissolved in water isn't neutral, but always basic. Evaporating a neutral solution of NaCN will liberate HCN. Evaporating a basic solution won't.
 
 
 
 
    Elementary
(Hive Bee)
01-26-02 16:23
No 261267
      Re: HCN, NaOH and BzCN  Bookmark   

The way I dreamed of doing it was to excess on the HCN in the NaOH pot and then remove the excess of HCN but heating the solution in a fume cupboard.

The whole procedure should be done in a fume cupboard idealy or outside while wearing protective clothing and a gasmask.

Please please be carefull, you done get any second chances with cyanide !

One day I'll understand everything !
 
 
 
 
    PolytheneSam
(Master Searcher)
01-26-02 17:44
No 261297
      Re: HCN, NaOH and BzCN  Bookmark   

I think CO2 in the air can displace the CN-, ie.

CO2 + H2O --> H2CO3
NaCN + H2CO3 --> NaCO3 +HCN

BTW, one time when I made some sodium aluminate from Red Devil Lye and aluminum foil, after I filtered it and let it stand for a while (2 days?) a precipitate formed which I didn't expect.  I figured it was alumina which I was trying to make in the first place and it saved me the trouble of adding acid to precipitate the alumina.  After that I found something in a chemistry book in the library where it said (and showed equations) that CO2 in the air can displace the alumina.  Also, after that I heated the fine hydrated alumina ( Al(OH)3 ) powder I got in an evaporating dish on a hot plate (to get Al2O3 ) and noticed little bubbles coming up through the dry powder.  I left it out and it hardened and I broke it up into pieces.

http://www.geocities.com/dritte123/PSPF.html
 
 
 
 
    blondie
(Stranger)
01-26-02 18:12
No 261314
      Re: HCN, NaOH and BzCN  Bookmark   

Elementary,

you suggest excessing the HCN in the NaOH. Then heating the solution (to boiling) to rid all the dissolved HCN - obviously piping this into a second pot of NaOH. whats the best way to monitor the excess point - no more uptake from the HCN generator or by pH (what level?). I feel that the preparation on Rhodiums page is not complete without a few more details - particularly if excessing then the requirement of a second vessel of NaOH.

this is not for p2p otherwise id do a grignard or knoevenagel condensation. i dont see many other feasable routes to BzCN. both BzCN and alkali metal cyanide salts are impossible to buy here.

thanks to the bees for their help.
 
 
 
 
    PPyroReached600
(Stranger)
01-26-02 18:19
No 261321
      Re: HCN, NaOH and BzCN  Bookmark   

Didn't jim post the reaction of

CHCl3 + 4NaOH + NH3 ==H2O==> NaCN + 3NaCl + 4H2O

I believed he called it the (something) isonitrile synthesis. When chloroform is used with sodium hydroxide, the HCN produced reacts with the alkalai, forming the salt.

Hey, Elementary, wouldn't that be a candidate for your acetonitrile synthesis?

1,1,1-trichloroethane + ammonia + 3NaOH --> MeCN + 3NaCl + 3H2O

                                                    PrimoPyro

Guess who exceeded his alotted Hive bandwidth today?
 
 
 
 
    Elementary
(Hive Bee)
01-26-02 18:25
No 261327
      Re: HCN, NaOH and BzCN  Bookmark   

No the heat would drive off the HCN in the solution, leaving you with just NaCN and Water. I know the boiling point of HNC is 25.86c, not sure if it forms a constant boiling liquid with water ?

Polythenesam, the CO2 possibly entering the solution while the HCN is being driven out by warming will be very small if any.



One day I'll understand everything !
 
 
 
 
    halfapint
(Ubiquitous Precursor Medal Winner)
01-26-02 18:32
No 261334
      Re: HCN, NaOH and BzCN  Bookmark   

1,1,1-trichloroethane + ammonia + 3NaOH --> MeCN + 3NaCl + 3H2O

Gotta bee somethin wrong. Can't tell me it's that easy.

Pyro burnin up the data channels, yow.

turning science fact into <<science fiction>>
 
 
 
 
    PPyroReached600
(Stranger)
01-26-02 18:34
No 261336
      Re: HCN, NaOH and BzCN  Bookmark   

Dear god! I completely take back the 1,1,1-trichloroethane reaction! That is one fucking expensive material! Totally not worth the money if used for this reaction.

$138/500mL or $377/4L

Holy shit!

                                                PrimoPyro

Guess who exceeded his alotted Hive bandwidth today?
 
 
 
 
    blondie
(Stranger)
01-26-02 18:36
No 261337
      Re: HCN, NaOH and BzCN  Bookmark   

PrimoPyro made a couple of posts last night before i went home - ive just got out of bed and hes still onlinetongue. ill see if i can find a write up of the chloroform, lye and ammonia prep.

Elementary, i understand that you drive off disolved HCN gas leaving the desired NaCN and water. The second pot is just to avoid the unwanted HCN venting outside the system. i hadnt considered the possibility of an azeotrope though.
 
 
 
 
    jim
(Hive Bee)
01-26-02 20:03
No 261375
      Re: HCN, NaOH and BzCN  Bookmark   

The Hoffman isonitrile synthesis...  Only works with primary amines, like NH3
 
 
 
 
    Aurelius
(Hive Bee)
01-27-02 14:39
No 261556
      Re: HCN, NaOH and BzCN  Bookmark   

Jim, have you tried running the Hoffman isonitrile synthesis?  (the one above in particular)  if so, do you have exact numbers for it?  do you think it could be run in a "kitchen chemistry" style, or will it have to be more exact?  (kitchen chemistry does not denote lack of safety precautions, just want to avoid the task of measuring everything exactly)
 
 
 
 
    halfapint
(Ubiquitous Precursor Medal Winner)
01-27-02 16:41
No 261573
      Re: HCN, NaOH and BzCN  Bookmark   

Hm, the Hofmann isonitrile synthesis corresponding to aceto(iso)nitrile would bee methylamine + chloroform + NaOH; for benzyl (iso)cyanide, it should come from benzylamine, chloroform, and NaOH.

~ ~ ~ ~ ~ C U N D C ~ ~ ~ ~ ~ ~
~ ~ four twenty oh oh three ~ ~
 
 
 
 
    PrimoPyro
(Hive Prodigy)
01-27-02 16:59
No 261578
      Re: HCN, NaOH and BzCN  Bookmark   

What the hell is an isocyanide? HNC=? HNC=H2? HNCH-CH3?

benzonitrile would be PhCN. What would be benzoisonitrile? PhNC=? The bonds don't add up. Ph-N=C=?

Vivent Longtemps la Ruche!
 
 
 
 
    blondie
(Stranger)
01-27-02 20:20
No 261675
      Re: HCN, NaOH and BzCN  Bookmark   

Uemura dreamed about the isonitrile synth with ammonia some time ago and did a write up Post 57287 (uemura: "Dreams of a KCN synthesis", Methods Discourse). seems to be a lot of unknown variables still - and not just in the workup. without a good prep or ref to follow blondie thinks this is outside her comfort zone <edit>.
 
 
 
 
    uemura
(Hive Photographer)
01-28-02 07:35
No 261830
      Re: HCN, NaOH and BzCN  Bookmark   


Uemura dreamed about the isonitrile synth with ammonia some time ago




Yes he did, but no comments nor good nor bad.

Just jim did once refer to this isonitril synthesis....


Carpe Diem
 
 
 
 
    Rhodium
(Chief Bee)
01-29-02 16:11
No 262472
      Re: HCN, NaOH and BzCN  Bookmark   

Benzoisonitrile is indeed Ph-NC with a tetravalent nitrogen and a trivalent carbon (and all the resonance forms you can think of).
 
 
 
 
    PrimoPyro
(Hive Prodigy)
01-29-02 17:44
No 262518
      Re: HCN, NaOH and BzCN  Bookmark   

That can't be stable! crazy

So do all isonitriles rearrange to nitriles with heating? If not, they should either decompose, or polymerize somehow. This is not stable without special conditions.

                                                     PrimoPyro

P.S. Rhodium: I had looked at a lot of chemfinder data and reached the same conclusion, but didnt want to post about it, as everyone seems to understand it while I dont. blush

Vivent Longtemps la Ruche!
 
 
 
 
    Rhodium
(Chief Bee)
01-29-02 19:14
No 262564
      Re: HCN, NaOH and BzCN  Bookmark   

NO (nitric oxide) and CO (carbon monoxide) is also of this type of bond, so it can be relatively stable.

However, isonitriles are very reactive, forming carbamates with alcohols, and is hydrolyzed by anything acid.
And yes, isonitriles are prone to polymerize, forming urethanes with polyhydric alcohols for example.
 
 
 
 
    PrimoPyro
(Hive Prodigy)
01-29-02 19:29
No 262572
      Re: HCN, NaOH and BzCN  Bookmark   

Thanks Rhodium. Good to know, and very interesting. I dont see a use for these two complxes it forms yet, but Im sure in time, they will resurface as the key feature of a new idea. All in good time...

                                                   PrimoPyro

Vivent Longtemps la Ruche!
 
 
 
 
    Greensnake
(Newbee)
01-30-02 08:26
No 262763
      Re: HCN, NaOH and BzCN  Bookmark   

Just random comments:
1. Isonitriles stink. No, they really stink. They stink ROYALLY. Don't be suprised, when you succeed to make one.

2. Hoffman isonitrile synthesis is generally low or medium yielding. If you get 50% of final product, consider yourself lucky.

Greensnake