Phenol, 2,4-di

Epoxy resins (di-phenolic chains) are closely related to phenol formaldehydes and are widely used to make reinforced composites with glass or carbon reinforcing fibers. Their monomers are cross-linked at lower temperatures than phenolic formaldehydes. Typical hardnesses for them are Hv = 4.4kg/mm2 (Olivier, et al., 2008). 

These additives are phosphorus esters of a di- phenol with the following structure ... 

The sum of all di-phenols and poli-phenols, here denoted as undesired product W... 

In a similar way, sodium hydroxide hydrolysis of the proerythrinadienone 71 (obtained by VOF3 oxidation of norprotosinomenine trifluoroacetamide) brings about its rearrangement to an intermediate which on reduction gives the di-phenolic dibenzazonine 35a in excellent yield (59) (Scheme 18). In contrast,... 

Guaiacol.—Another common method of preparing this phenol is from one of its derivatives known as guaiacol, a naturally occurring substance (p. 621). It is the methyl ether of the di-phenol which it yields on heating with water and aluminium chloride. 

At ordinary temperatures the sulphonation of phenol yields mostly the ortho compound with some of the para. At raised temperatures the para compound only is obtained, the first formed ortho compound being converted into the para. The meta compound is not formed by direct sulphonation of phenol. As previously stated (p. 522), the alkali fusion of di-sulphonic acids yields the di-phenols. By careful fusion... 

It is interesting that the para benzene di-sulphonic acid also yields the meta phenol sulphonic acid due to position rearrangement. This same rearrangement, it will be recalled, occurs in the stronger fusion of the para di-sulphonic acid, meta di-phenol being obtained (p. 522). Amino benzene sulphonic acid may also be converted into phenol sulphonic acid by diazotization and decomposition of the diazo compound with water. 

Protocatechuic Aldehyde.—A di-phenol aldehyde, viz., the 3-4-di-hydroxy benzaldehyde, is known as protocatechuic aldehyde because it yields protocatechuic acid on oxidation. 

Just as protocatechuic aldehyde may be synthesized by the Reimer-Tiemann or Gattermann-Koch reactions from the -di-phenol pyro-catechinol, so vanillin may be made by the same reactions from the mono-methyl ether of pyrocatechinol, Le.f guaiacol (p. 621). 

Eel. low rate of excr. in rats, rab., man. UGC (rat) des-acetyl. bis-des-acetyl., rat (M) and conj. (glue.) C=C cleavage, man (M) and conj. (glue.). In rats, bulk excr. in faeces. Similar data with free di-phenol (65). 

BRN 2294370 EINECS 201-239-5 4,4 -lsopropylidene-bis(2-t-butylphenol) 4,4 -lsopropylidenebis(o-t-butyl-phenol) Phenol, (22 -di-t-butyl-4,4 -isopropylene)di- Phenol, 4,4 -(1-... 

Since the chlorogenic acid content was reported to be higher in inner (younger) than in outer bracts, the blackening which is caused by the effect of polyphenol oxidase on ortho-di-phenols is much greater in the inner tissues of the head [39]. 

Figure 3.10 Hyperbranched PPV from 4,4 -(p-Phenylenedi-l,2-ethenediyl)-di-phenol and l,l,l-Tri-(p-tosyloxymethyl)-propane ...

One or two Al(III) cationic porphyrin(s) is (are) connected with a peripheral mono- or di-phenolic free base, and their photophysical properties are compared with previously described tin(IV), germanium(IV), and phosphorous(V) oxophilic porphyrins. Two processes can occur in these nonelectronically coupled species, the first being observed upon excitation of the aluminum porphyrin. When excited at 550 nm, the Al(II) species fluorescence is quenched by the free base component mostly by energy transfer, but concomitantly by electron transfer in polar media. The second process occurs upon excitation of the free base species, and consists in a poorly efficient (low <2h2%) electron transfer from the free base to the Al(ni) species. The same process is quite efficient in the case of P(V), Sn(IV), and Ge(IV) analogs with respective 0H2 values of 93, 82, and 69%. ... 

Two di(electrophilic) macromers were prepared and functionalized with 2-oxazollne chain ends. a,o)-Di(chloroallyl) aromatic polyether sulfone (PSU-CA) and a,o)-di(bromobenzyl) aromatic polyether sulfone (PSU-BX) were prepared by the phase transfer catalyzed reaction (in chlorobenzene, 12% aqueous NaOH) of a,o)-di(phenol) PSU with cis-1,4-dichloro-2-butene and a,a -dlbromo-p-xylene respectively (Scheme 2). a,o)-Dl(phenol) PSU was prepared from bisphenol-A and 4,4 -dichlorodiphenyl sulfone.The detailed synthesis and characterization of a,w-di(electrophilic) PSU has been described previously. However, it is important to mention here that in order to achieve quantitative functionalization of the pol3oner chain ends it is necessary to carry out the reaction in aromatic solvents, in the presence of stoichiometric amounts of phase transfer catalyst versus phenol chain ends, and in the presence of relatively dilute aqueous NaOH solution. Using high... 

Figure 1 shows an NMR spectrum of an a,o)-di(phenol) PSU and Figure 2 shows the spectrum of an example of a,co-di(phenol) PSU functionalized with bromobenzyl chain ends. As can be seen in the spectrum, the reaction was complete giving only bromobenzyl chain ends. 

The operational stability of the HRP and CDH biosensors was studied by repeated injections of (di)phenols (phenol and dopamine, respectively) with a steady-state supply of substrate (H2O2 or cellobiose), see Figure 6. During one hour the response decreased about 2-3% for both biosensors. 

As can be seen in Table II the responses within a group of related compounds differ. This may be due to differences in enzyme selectivity but also in how efficiently the (di)phenols are oxidized/reduced at the electrode surface, especially in the case of the CDH biosensor where the applied potential is rather close to the formal potential of several of the diphenols. The differences are probably also caused by differences in the stability of the products formed in the electrochemical reduction/oxidation and/or enzymatic reduction. Another possible explanation is the formation of by-products that cannot be recycled between the enzyme and the electrode. 

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