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Author: Subject: Benzonitrile in different ways
MrMario
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[*] posted on 4-4-2016 at 02:46
Benzonitrile in different ways


I want to explore some new ways in synthesis to learn more about mechanisms and chemistry itself. I have two very easily to obtain chemicals, Benzoic acid and Ammonia and would like to make Aniline from those (reducing agent may be the tricky one).

Since Aniline is mainly made by nitration of Benzene and reducing this to NH2 I want to discover some new ways with easier to obtain chemicals.

I quoted this from Wikipedia:
"Benzonitrile was reported by Hermann Fehling in 1844. He found the compound as a product from the thermal dehydration of ammonium benzoate. He deduced its structure from the already known analogue reaction of ammonium formate yielding formonitrile. He also coined the name benzonitrile which gave the name to all the group of nitriles."

Another possible way I found is through dry distillation of Zinc Dibenzoate with Lead Thiocyanate. This one seems to work quite well in +50% yields and except Lead Thiocyanate has no hard to obtain chemicals.

The second method works by the following proces, called Lets Nitrile synthesis:
"In 1857 Hugo Schiff observed that the reaction between benzoyl chloride with potassium cyanide produced the desired benzonitrile.[3] Work done later by British chemist Edmund A. Letts delved much deeper into the synthesis of nitriles. Attempting first to add cyano-groups to acetic acid, he obtained a mixture of acetamide and carbonyl sulfide. However, in 1872 he showed that treating a 2:1 molecular ratio of benzoic acid and potassium thiocyanate with heat for several hours also produced nitriles with only a small amount of amide with about 40% yield.[4]

G. Kr├╝ss expanded on Letts' work in 1884, producing better yields by utilizing lead(II) thiocyanate.[5] In 1916, E.E. Reid found that showed that dry distillation of the zinc(II) salt of the acid with a 20% excess of lead(II) thiocyanate gave an 86% conversion and 91% yield, almost double of that produced by Letts"

Since Benzonitrile is a pretty useful chemical to Amines, Imines, Aldehydes, Ketones, Phenones, ect. I want to try these and give some valuable feedback if possible. Has anyone tried one of these methods before or does anyone have tips?

[Edited on 4-4-2016 by MrMario]
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byko3y
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[*] posted on 4-4-2016 at 05:10


Obviously, Kruss, Letts and Reid tried those methods, there's a lot of other researches done about this method, as well as other methods. Nitriles are widely used in organic chemistry, thus nobody is gonna really help you until you have some specific case.
For example, I can tell you about production of benzonitrile from benzamide Japanese Patent JPS6032758
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MrMario
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[*] posted on 4-4-2016 at 05:46


Thanks for the method I will have a look at it.
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UC235
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[*] posted on 4-4-2016 at 08:18


http://www.sciencemadness.org/talk/viewthread.php?tid=7194

Garage_Chemist had an excellent writeup on versuchschemie.de, but I am having trouble locating it in an archive since the forum has vanished.

You might want to skim this thread on benzamide prep:
http://www.sciencemadness.org/talk/viewthread.php?tid=4201&a...

There is also the attached paper using benzamide and ammonium sulfamate:

Attachment: nitriles.pdf (381kB)
This file has been downloaded 188 times

[Edited on 4-4-2016 by UC235]
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[*] posted on 4-4-2016 at 19:31


Just for information. We once tried heating sulfamic acid (2 mole equiv), benzoic acid (1 mole equiv) and urea (2 mole equiv) together as we'd read that this can react and form benzonitrile and we wanted to experiment on a small scale to try it out.

The mixture weirdly forms a paste when mixed together (even though the ingredients were dry) and then reacts very vigorously at about 150C (with the temp rising to 200C) with a lot of the material being ejected through the flask neck!

There's definitely a very strong almondy benzonitrile aroma, but very hard to isolate anything at all.

Interestingly no combination of 2 ingredients when heated reacted in the same way, so it's definitely a combination of the three that's reacting. We didn't experiment further!




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