1,3,5-Triphenylhexahydro-1,3,5-triazine - active intermediate and precursor in the novel synthesis of benzoxazine monomers and oligomers

Abstract

SUMMARY:The benzoxazine monomer synthesis via 1,3,5-trialkyl(aryl)hexahydro-1,3,5-triazine intermediate is followed by 1 H NMR, FT-IR, and SEC. A model compound, 1,3,5-triphenylhexahydro-1,3,5-triazine, is synthesized independently and its reaction with bisphenol-A and paraformaldehyde in stoichiometric amounts is also followed by 1 H NMR. Additional model compounds, 1,3,5-trimethyl(ethyl)hexahydro-1,3,5-triazine, are used instead of a primary amine to synthesize bifunctional benzoxazine monomers, bis(3,4-dihydro-2H-3-methyl(ethyl)-1,3-benzoxazinyl)isopropane, via novel solventless reaction with bisphenol-A in the presence of paraformaldehyde. The mechanism of this reaction is proposed.

Structurally diverse benzoxazines: synthesis, polymerization, and thermal stability

“…The presence of oxazine ring in the prepared compounds was further supported by the appearance of new absorption bands due to asymmetric and symmetric stretching of oxazine at 1230 and 1500 cm À1 , respectively. In addition, the oxazine ring frequency [23][24][25] (948 cm À1 ) was observed for all the materials. The presence of a band at 2951 cm À1 in IBPB and a characteristic band at 2962 cm À1 in SBIB confirm the existence of intact indane and spirobiindane nucleus in IBPB and SBIB, respectively.…”

Study on products and reaction paths for synthesis of 3,4-dihydro-2H-3-phenyl-1,3-benzoxazine from phenol, aniline and formaldehyde

“…The 13 synthesis of benzoxazine monomer was first reported by Holly and 14 Cope [8], in which it can be obtained by a variety of synthetic 15 routes [9][10][11][12]. The most universal route is using phenols, primary 16 amines, and formaldehyde as starting materials [3,[13][14][15][16][17][18].…”

“…A more 232 reasonable intermediate probably is N-hydroxymethyl aniline 233 (HMA), which could be further transformed to compounds 2, 3 234 and 10, although no existence of HMA could be confirmed yet 235 [29,30]. In addition, in a previous report about benzoxazine 236 synthesis [10], the active intermediate of compound 9 could 237 also be generated from the self-reaction of HMA, which further 238 imply that HMA is possibly the key intermediate. The probable 239 path of the reaction may be as following: formaldehyde initially 240 reacts with primary amine to generate HMA, which subsequently 241 reacts with other reactants and intermediates to give the final 242 products.…”

“…The first step of reaction is 250 the formation of active intermediate HMA, which is derived from 251 the reaction between formaldehyde and primary amine. One HMA 252 molecule then reacts with the other HMA molecule to generate 253 compound 9, which can be converted into benzoxazine by reacting 254 with paraformaldehyde and phenol [10] (Scheme 2, path a). 255 However, if HMA attacks at the ortho position of phenol, then it will 256 form compound 3, which can also immediately transform into 257 benzoxazine via reaction with formaldehyde (Scheme 2, path b) 258 [31].…”

Fatty acid-derived α,ω-bis-benzoxazines through hydrosilylation; curing and thermoset properties

“…1,3,5-triphenylhexahydro-1,3,5-triazine [21,22] was synthesized according to reported procedures. All solvents were purified and dried by standard methods.…”