Search results
Results From The WOW.Com Content Network
Formaldehyde is a common precursor to more complex compounds and materials. In approximate order of decreasing consumption, products generated from formaldehyde include urea formaldehyde resin, melamine resin, phenol formaldehyde resin, polyoxymethylene plastics, 1,4-butanediol, and methylene diphenyl diisocyanate. [40]
Phenol-formaldehyde resins, as a group, are formed by a step-growth polymerization reaction that can be either acid- or base-catalysed.Since formaldehyde exists predominantly in solution as a dynamic equilibrium of methylene glycol oligomers, the concentration of the reactive form of formaldehyde depends on temperature and pH.
Reactions between aldimines and α-methylene carbonyls are also considered Mannich reactions because these imines form between amines and aldehydes. The reaction is named after Carl Mannich. [2] [3] Scheme 1 – Ammonia or an amine reacts with formaldehyde and an alpha acidic proton of a carbonyl compound to a beta amino carbonyl compound.
Urea-formaldehyde is widely utilized due to its inexpensive cost, quick reaction time, high bonding strength, moisture resistance, lack of color, and resistance to abrasion and microbes [9]. Examples include decorative laminates, textiles, paper, foundry sand molds, wrinkle-resistant fabrics , cotton blends, rayon , corduroy , etc.
On it, two chemical reactions simultaneously produce formaldehyde: the one shown above, and the dehydrogenation reaction: CH 3 OH → H 2 CO + H 2. Further oxidation of the formaldehyde product during its production usually gives formic acid that is found in formaldehyde solution, found in parts per million values.
To the average consumer, formaldehyde may be best known as an embalming agent. But this naturally occurring chemical is a major industrial staple, used in many consumer goods, including cleaning ...
Bakelite was produced for the first time in 1872 by Adolf von Baeyer, though its use as a commercial product was not considered at the time. [6]Leo Baekeland was already wealthy due to his invention of Velox photographic paper when he began to investigate the reactions of phenol and formaldehyde in his home laboratory.
The production of DMEU is through the condensation of formaldehyde with ethylene urea: [9] 2CH 2 O + (C 2 H 4 N 2 H 2)CO → (C 2 H 2 N 2 (CH 2 OH) 2)CO. The reaction proceeds around 200 °C (392 °F) but this temperature can be brought down to around 70 °C (158 °F) in the presence of an acid catalyst. [10]