Formation of alkoxy groups in the synthesis of butylated urea formaldehyde resins: Reaction mechanism and kinetic model

Etherified Amino Resins with Tailor-Made Properties: A Holistic Approach via Polymerization

“…Subsequently, these ingredients are converted to the BUF resin via condensation reactions. The key features of the addition reactions and the mechanisms involved have already been described in our previous work; these reactions are butylation reactions and the formation of X-condensates. Here, therefore, we present only the reactions that are involved in the condensation step, that is, butylation reactions and Z-condensates or oligomer formation reactions.…”

“…The reactions to R4 are butylation reactions that involve the combination of Bu with methylol derivatives . Unlike the addition step, where the reactor is maintained under neutral pH conditions, the butylation reactions have been shown to occur also in the condensation step under acidic conditions ,− to form methylene linkages (−CH 2 −) ,,,, of Z-condensates. …”

“…For instance, P 0,1 3,1 , represents a NB monomeric species ( i = 0, k = 1) in which one H-atom of the −NH 2 group of urea has been substituted by one −CH 2 OH group ( a = 3, b = 1), while P 1,1 3,0 represents its mono-butylated counterpart. In Table , we represent the key molecular species involved in the condensation reactions in generic form; the A , B , C , and D representations, , which have been used in the addition reactions in our previous work, are shown side-by-side for clarity. Using this scheme, therefore, the butylation reactions −R4 and the polymerization reactions and R6 can be rewritten as reactions and , respectively. …”

“…Because of this reason, the chemistry of BUF resins becomes intricate, and therefore, in order to determine the quality parameters for the resin, the kinetics of the entire synthesis process needs to be simulated. The detailed reaction mechanism and its kinetics for the addition step, however, have been discussed in our previous work . Here, we focus our discussion on the condensation step and highlight its similarities and differences with the addition step, wherever needed.…”

“…For instance, in the addition step, the methylol reactions dominate over butylation reactions, whereas, in the condensation step, the butylation and polymerization reactions dominate over all the other reactions. Some amount of polymerization also occurs in the addition step through the formation of −CH 2 –O–CH 2 – linkages. ,, In the condensation step, however, the formation of −CH 2 – linkages ,, through polymerization is dominant.…”