Sciencemadness Discussion Board

Aluminium and molten urea/benzoic acid

Random - 16-6-2011 at 06:33

I am thinking about preparing more benzamide now and I will put urea and benzoic acid into aluminium coke can and then melt that stuff in the fire until benzamide is prepared. I would do this because that coke can is cheap and easy to obtain. I have one question, does molten urea, benzamide, ammonia or benzoic acid damage the aluminium at those temperatures?

woelen - 16-6-2011 at 06:57

I expect strong corrosion of the aluminium. Ammonia is quite alkaline and especially if moisture is present as well (or is formed in the reaction), then at the high temperatures involved in your setup you can expect fairly quick reaction.

In any case, I expect the temperature to be too high when the can is put in fire without any moderation of temperature. The thin aluminium of the coke can will pass the heat of the fire to the reaction mix with almost no attenuation. You probably will have considerable charring of the reagents as well.

If you really want a clean reaction than at least use a teflon coated pan and a hotplate which allows some moderation of the temperature and reaction conditions. You also have some possibilities of inspecting the reaction mix while it is going on.

smuv - 16-6-2011 at 07:14

aluminum cans are plastic lined.

bbartlog - 17-6-2011 at 04:21

Aluminum will react with NH4OH; not sure about NH3. But in any case, the heat will decompose the plastic coating smuv mentions, and then the aluminum will (at best) contaminate your product via side reactions or (more likely) develop a hole as it reacts/corrodes. Aluminum soda cans aren't good reaction vessels, at all. Even a steel soup can is better.

Globey - 17-6-2011 at 09:08

Right, copper would be better, glass the best. Even polytef. What do you want with the benzamide BTW, anti nausea ?

Random - 19-6-2011 at 03:01

I'll take then steel tuna can or beans can that contains iron. Maybe it will contaminate some of the product with iron, but I am sure it won't react :D

I will make aniline and possibly benzyl alcohol from benzamide.

LanthanumK - 19-6-2011 at 03:19

Once, I heated the lid of a common "tin can" in the fire and it ignited. There is a layer of flammable substances on one side of the can. Will heating cause these to decompose and contaminate your chemical?

[Edited on 19-6-2011 by LanthanumK]