Linear all‐ortho oligomers of phenol–formaldehyde resins. I. Preparations, characterizations, and solution properties

Abstract

Three kinds of all‐ortho methylene‐linked phenolic oligomers, i.e., 4‐tert‐butylphenol (BP), phenol (AO), and O‐methylated BP (BPM), were prepared with good yields and their dilute solution properties were studied. In acetone, all of these oligomers are highly solvated and molecularly dispersed. In chloroform, however, AO and BP molecules strongly form hydrogen bonds among themselves. By intramolecular and intermolecular hydrogen‐bondings, a large portion of the dimers and the trimers of AO and BP associate to form bimolecular aggregates in chloroform, assuming pseudo‐cyclic conformations analogous to calix [4] arene and calix [6] arene, respectively. By intramolecular hydrogen‐bonding, the tetramers and the hexamers also form pseudo‐cyclic conformations by themselves in chloroform. © 1993 John Wiley & Sons, Inc.

Synthesis of Macrocyclic Receptors with Intrinsic Fluorescence Featuring Quinizarin Moieties

“…(OPLS_2001 forcefield, MCMM, 1,000 steps). 37 . The phenolic trimer 3 (5.50 g, 11.6 mmol) was dissolved in THF (130 ml) and DMF (10 ml).…”

Polymers Based on Phenols

“…Many workers have since investigated this phenomenon in higher oligomers 25,27,30 . Higher acidity values are observed with increasing chain length as found for linear oligomers with a terminal p-nitrophenol unit, which may stabilize the mono-anion.…”

“…Investigations of the reactivity of ortho-linked oligomers towards formaldehyde under acidic conditions showed that as the chain length is increased, the shielding and deactivating effects of intramolecular hydrogen bonding decreased the reactivity 34 . There is recent evidence 25,35,36 to suggest that in solution at least, a large proportion of the ortho-linked oligomers adopt pseudo-cyclic conformations. The molecular freedom of liquid resins may be somewhat restricted by such hydrogen bonding, thereby hindering their ability to adopt conformations favourable for chain extension or crosslinking 31 .…”

“…23 . A series of exclusively ortho-ortho linked low molecular weight Novolac resins derived from phenol and formaldehyde 24,25 , acetaldehyde 26,27 and isobutyraldehyde 28 has also been synthesized.…”

Preparation and characterization of para-tertiary-butylphenol formaldehyde resins using dual catalytic-extraction method

“…Yamagishi et al [11] reported the synthesis of methylene-linked para-tertiary-butylphenol oligomers through tri-nuclear precursor with hydrochloric acid as the catalyst. The limitation of this type is that the viscosity of the system is too high to stir in the late stage of polymerization, which is detrimental for the preparation of resins with high molecular weight.…”