Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: 37% formaldehyde
International Hazard

Posts: 2953
Registered: 18-1-2007
Location: UTM
Member Is Offline

Mood: LaGrangian

[*] posted on 8-4-2007 at 21:16
37% formaldehyde

from formic acid one can make Ca Formate and from that formaldehyde gas. My question is: is there an easy way to tell when you get to 37% aqueous solution eg specific gravity? If so do you add the MeOH (stabilizer) afterwords? I would think so but the main question was how to tell when you get there.
View user's profile View All Posts By User
International Hazard

Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 8-4-2007 at 21:29

See Org.Syn. for an explanation of the difficulties in assaying aqueous formaldehyde by density.

Although their objections mostly had to do with varying amounts of methanol so if you are adding methanol afterwards you might be alright.

But you are going way long way round the block wasting good formic acid.

You make formaldehyde by running methanol vapor over heated copper. Methanol is a whole lot easier than formic acid to get and a lot cheaper.

But, formalin (37% soln formaldehyde) is also easy to get and cheap so I fail to see why you are bothering .

Also you can buy paraformaldehyde (solid) and very often generate formaldehyde in situ from it. Trioxane is also used in same way.
View user's profile View All Posts By User

Posts: 28
Registered: 19-11-2006
Location: Moscow, Russian Federation
Member Is Offline

Mood: Content

[*] posted on 9-4-2007 at 07:52

one of the best and most precise ways to analyze % of formaldehyde solution is DNPH (dinitrophenylhydrazine). It forms quite a stable hydrazone with almost quantitative yield -> gravimetric analysis, etc.
View user's profile View All Posts By User

  Go To Top