psyloxy
(Hive Addict)
09-09-03 21:55
No 458067
      novel synthesis of O-Acetyl-Mandelonitrile
(Rated as: good idea!)
    

Synthesis of 3,4,5-trimethoxybenzaldehyde cyanohydrin acetate and subsequent reduction thereof with Pd/H2 @ 1atm is described in ../rhodium /mescalyptus.html

Yield of acetylated mandelonitrile is only ~66% from the benzaldehyde. It involves the use of KCN.

In Ref[1] O-acetyl-mandelonitrile is prepared in 90% yield at ambient temp in 1 hour from benzaldehyde, 2-oxo-propionitrile and aq. K2CO3 soln. in acetonitrile.

No, I have not read the article. Yes, I want to know what it says,too.

Now, what is 2-oxo-propionitrile and how is it made ?

I hope you can guess it's structure from the following little ascii drawing:
             
H3C-C=O
     \
      CN



There must be a hundred ways to make it.

[2] Wacker oxidation of acrylonitrile @ 30°C
[3] from KCN and acetylbromide

Dehydration of 2-oxo-propionaldehyde oxime
[4] with P2O5 in CS2
[5] with acetylchloride

Of these I think 2-oxo-propionaldehyde oxime holds the most promise for it can be prepared from acetone and

[6]ethylnitrite (74% - 45°C - 60min) [looks somewhat familiar,eh ?]
[7]methylnitrite / HCl
[8]AcOH / NaNO2 at 0°C
[9]N2CO3 / Na2[Fe(CN)5NO] (sodium nitroprusside)

There are tons more ways out there but one thing sticks out especially: in Patent US2980708 they describe the thermal rearrangement of easily made oxime-acetate
to nitrile by dry distillation. They use the corresponding epoxialdoximes(and produce the epoxinitriles which,in turn, can also be used to make the oxonitriles) but it might as well work on the oxy-aldoxime, too.

comments eagerly awaited laugh

BTW: you may encounter the use of Ac2O here and there if you're doing research into this topic, besides it's quite useful generally, may it be for the production of AcBr from Ac2O and HBr, which may sound like the wrong way but have a look at Patent US1430304 where Henry Dryefuss demonstrates how to make Ac2O by simpy heating a mix of Na2S2O7 and NaOAc. It has once been mentioned before by PolytheneSam but maybe wasn't recognized ??



[1] Okimoto, Mitsuhiro; Chiba, Toshiro; SYNTBF; Synthesis; EN; 10; 1996; 1188-1190.
[2] Smidt; Sieber; ANCEAD; Angew.Chem.; 71; 1959; 626.
[3] Mukherjee, Jogeshwar; Rogers, Janice I.; Khalifah, Raja G.; Everett, Grover W.; JACSAT; J.Amer.Chem.Soc.; EN; 109; 23; 1987; 7232-7233
[4] Scholl; MOCMB7; Monatsh.Chem.; 39; 1918; 238.
[5] Claisen; Manasse; CHBEAM; Chem.Ber.; 20; 1887; 2196
[6] Tajbakhsh, M.; Bakooie, H.; Ghassemzadeh, M.; Beheshtiha, Y. Sh.; Heravi, M. M.; IJSBDB; Indian J.Chem.Sect.B; EN; 40; 12; 2001; 1232 - 1233
[7] Slater; JCSOA9; J.Chem.Soc.; 117; 1920; 589.
[8] Kuester; HSZPAZ; Hoppe-Seyler's Z.Physiol.Chem.; 155; 1926; 180.
[9] Schmidt; ARPMAS; Arch.Pharm.(Weinheim Ger.); 250; 1912


--psyloxy--
 
 
 
 
    Rhodium
(Chief Bee)
09-09-03 23:30
No 458084
      PhCHO + AcCN -> O-Acetyl-Mandelonitrile
(Rated as: good read)
    

A Convenient and Improved Method for the Preparation of Cyanohydrin Esters from Acyl Cyanides and Aldehydes
M. Okimoto & T. Chiba
Synthesis (10), 1188-1190 (1996) (../rhodium/pdf /mandelonitrile-acetate.phcho-acetylcyanide.pdf)
 
 
 
 
    psyloxy
(Hive Addict)
09-10-03 03:14
No 458142
      refs for the preparation of benzoylcyanide     

So the autors indicate Ph-CO-CN can also be used. That made psyloxy look into preparation methods for this compound. Here's what he found.

[1]First let's prepare some acetoneoxime from, you guessed it, acetone and NH2OH.HCl. With the aid of Na2CO3 and hot aqu. EtOH 96% yield can be had in 24h.

In the 2nd step acetophenone is first oxidised to phenylglyoxaldehyde by DMSO/HBr then hydrated with H2O to phenylglyoxylhydrate, refer to ex. XI in Patent US3434064

[2]Said phenylglyoxalhydrate is then reacted with the aforementioned acetoneoxime + HCl for 2h in 50°C H2O to give a 91% yield of oxo-phenyl-acetaldehyde oxime

[3] Finally oxo-phenyl-acetaldehyde oxime is dehydrated with Ac2O to form oxo-phenylacetonitril

Now that reads 4 rxns at first sight. But look at them. Simple chems, simple (+mild) rxns, simple workup... pure chemical simplicity, no need to fool around with KCN, not even alkylnitrites! Well, from my theoretical point of view it all looks fine and dandytongue


[1]Langhals, Heinz; Range, Guenter; Wistuba, Eckehardt; Ruechardt, Christoph; CHBEAM; Chem.Ber.; GE; 114; 12; 1981; 3813-3830.
[2]Meester, Johan W. G. De; Plas, Henk C. van der; Middelhoven, Wouter J.; JHTCAD; J.Heterocycl.Chem.; EN; 24; 1987; 441-451.
[3]Hegarty, Anthony F.; Tuohey, Patrick J.; JCPKBH; J.Chem.Soc.Perkin Trans.2; EN; 1980; 1313-1317


--psyloxy--