2.6- Di-f-butylphenol

Methylenebis(2,6-di-/ /f-butylphenol) (25) (R = H) [118-82-17, the reaction product of two molecules of 2,6-DTBP with formaldehyde under basic conditions, is a bisphenoHc antioxidant. The quinone methide in this case is generated in situ. The product results from the addition of 2,6-di-/ /f-butylphenolate to (23) (12). 

When determining QSC values of dimeric lithium phenolates in solution, the value has to be corrected for anisotropic rotational diffusion as the complexes have an oblate, non-spherical shape . The Li2A2S2 complex of 2,6-di-f-butylphenolate has a Li QSC value of ca 280 kHz in a number of different solvents. The 2,6-dimethylphenolate system is present as an Li2A2S4 complex in THF and apparently as an L12A2S2 complex in DEE. These complexes have QSC values of 170 and 270 kHz in the two solvents, respectively. 

Figure 1. Degree of ionization of various phenols in aqueous DMSO as a function of solvent composition ( ) 2,6-di-isopropylphenol, (o) 2-t-butylphenol, (half-shaded circle) 2,4-di-f-butylphenol, ( ) 2,6-di-f-butylphenol, ( ) 2,6-di-f-butyl-4-methylphenol, (half-shaded square) 2,4,6-tri-f-butylphenol. (Albagli et al., 1973.)...

C-Arylation. The arylation of 2,6-di-f-butylphenol with various aryl bromides affords a series of 4-hydroxybiaryl derivatives. Introduction of an aryl substituent to the y-position of a,P-unsaturated carbonyl compounds is also realized. 

The classical front strain steric effect plays a significant role in infinencing the hydrogen-bond acidity of oriLo-substituted phenols. The introdnction of one ortho-a ky gronp into phenol lowers log LT (Table 3). A 2,6-dialkyl snbstitution prodnces a more severe steric inhibition to hydrogen-bond formation (Table 3) and 2,6-di-/-propylphenol and 2,6-di-f-butylphenol become so weak that they were exclnded from the analysis (Fignre 4). 

In structures such as 2,6-di-f-butylphenol, in which steric hindrance prevents hydrogen bonding, no bonded hydroxyl band is observed, not even in spectra of neat samples. 

A reaction of fundamental importance which belongs to this category has been investigated recently by Ershov and Volod kin (1962) and de la Mare et al. (1962). In the bromination of 2,6-di-f-butylphenol (20) in acetic acid, 4-bromo-2,6-di-t-butylcyclohexa-2,5-dienone (2) can be... 

The base, however, acts to abstract the proton from the a-haloketones to produce the a-halocarbanion. The latter is immediately removed by the reaction with the free, uncomplexed organoborane, and the transfer of alkyl group from boron occurs and product methyl ketone is obtained by the hydrolysis of the intermediate (Scheme 7.4) [2c]. It is significant to mention that protonolysis of the reaction intermediate by 2,6-di-f-butylphenol produced in the reaction is relatively difficult. Consequently, ethyl alcohol is added to liberate ketone. 

The problem is overcome by making 1-M solution of the organoborane in THE and then adding an equimolar quantity of 2,6-di-f-butylphenol, followed... 

Scheme 3.30 Oxidative coupling of 2,6-di-f-butylphenol using polyaniUne/Pd NPs under molecular oxygen...

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