Acetic acid with phenols

The rate of stripping or the stripabiUty on cataly2ed urethane and epoxy resin finishes can be increased by adding formic acid, acetic acid, and phenol. Sodium hydroxide, potassium hydroxide, and trisodium phosphate [10101-89-0] may be added to the formula to increase the stripabiUty on enamel and latex paints. Other activators include oleic acid [112-80-17, trichloroacetic acid [76-85-9], ammonia, triethanolamine [102-71-6], and monoethyl amine. Methylene chloride-type removers are unique in their abiUty to accept cosolvents and activators that allow the solution to be neutral, alkaline, or acidic. This abihty gready expands the number of coatings that can be removed with methylene chloride removers. 

Various 2,6-di8ubstituted p-benzoquinones have been prepared by oxidation of the corresponding 2,6-disubstituted phenols with potassium nitrosodisulfonate or lead dioxide in formic acid. Oxidative coupling of 2,6-disubstituted phenols to poly-2,6-disubstituted phenylene ethers followed by treatment of the polymers in acetic acid with lead dioxide is reported to give low yields of the corresponding 2,6-disubstituted p-benzoquinones. 

To place the acidity of phenol in perspective, note that although phenol is more than a million times more acidic than ethanol, it is over a hundred thousand times weaker than acetic acid. Thus, phenols can be separated from alcohols because they are more acidic, and from carboxylic acids because they are less acidic. On shaking an ether solution containing both an alcohol and a phenol with dilute sodium hydroxide, the phenol is converted quantitatively to its sodium salt, which is extracted into the aqueous phase. The alcohol remains in the ether phase. 

Combined effect of BTMA Br3 and ZnCl2 in acetic acid provides a new excellent bromination procedure for arenes. That is, while such reactive aromatic compounds as phenols, aromatic amines, aromatic ethers, and acetanilides have been easily brominated by BTMA Br3 in dichloromethane in the presence of methanol, the reaction of arenes, less reactive compounds, with BTMA Br3 in dichloromethane-methanol did not proceed at all, even under reflux for many hours. However, arenes could be smoothly brominated by use of this agent in acetic acid with the aid of the Lewis acid ZnCl2 (Fig. 13) (ref. 16). 

Only few applications have been reported to determine antioxidants in rubbers or polymers by using electrochemical methods [927,928]. Sawada et al. [929] reported successful separations by coupling the antioxidants with p-diazobenzene sulfonic acid before electrophoresis. Amine AOs were coupled in acetic acid and phenolic AOs in NaOH-ethanol were analysed by CE methods. MEKC separation of the four major food grade antioxidants (PG, BHA, BHT, TBHQ) was completed within 6 min with pmole amount detection using UV absorption [930]. RPLC was not as efficient and required larger sample amounts and longer separation times. 

In very reactive halogen derivatives such as a-bromo ketones [234] and a-bromothiophene [235] the halogens are replaced by hydrogen with hydrogen bromide in acetic acid provided phenol is added to react with the evolved bromine and to affect favorably the equilibrium of the reversible reaction. Hydrogen bromide in acetic acid also reduces azides to amines [232],... 

A brown dye, soluble in alcohol. Phenacetolin is a product resulting from the action of concentrated sulphuric acid on glacial acetic acid and phenol. The indicator solution is prepared by digesting 1 gm. of phenacetolin with warm alcohol, then diluting to 100 cc., and filtering. 

They have also been synthesised by condensing salicylic acid with phenols through the agency of sulphuric acid, acetic anhydride, etc. (B., 21, 502 24, 3982 25, 1652 26, 71 27, 1989 A., 254, 265). All four possible mono-hydroxyxanthones have been prepared in this way, as have some of the poly-hydroxy compounds. These latter are the more important. 

Attempts to confirm the structure of 32 by conversion into the methyl indolizine and comparison with an authentic sample were inconclusive. However, rearrangement of 27 with acetic acid or phenol gave an indolizine triester formulated as 33 which could be converted into 34. This last product had markedly different physical properties from 32 and its decarboxylation product was identical with 3-methylindolizine [Eq. (9)]. 

As already shown by Moore and co-workers9 and Tour and coworkers,10 addition of methyl iodide to a triazene resin at elevated temperature (110°) gives rise to aryliodides 17-1 (Nu = I) in excellent yields. We have shown that aryl halides 17-X (X = Cl, Br, I) are readily available by the action of lithium halides in the presence of an acidic ion-exchange resin or with the corresponding trimethylsilyl halide at room temperature.26 A mixture of acetic anhydride and acetic acid produces phenol acetates 17-OAc.26... 

Figure 1.7 shows both the experimental and predicted values (continuous line) of both the ICE and COD evolution with the specific electrical charge passed during the anodic oxidation of different classes of organic compounds (acetic acid, isopropanol, phenol, 4-chlorophenol, 2-naphtol). This figure demonstrates that the... 

Another unconventional deprotonation is seen with tyrosine. Gas-phase experiments by Kass indicate that deprotonation of tyrosine leads to a 70 30 mixture of the phenoxide 16 to carboxylate 17 anions." Kass optimized the structures of tyrosine and its two possible conjugate bases 16 and 17 at B3LYP/aug-cc-pVDZ, and computed the two DPEs at G3B3.17 is predicted to be 0.2 kcal mol lower in energy than 16 at B3LYP and slightly more stable at G3B3 (0.5 kcal mol ). However, both computational methods fail to predict the DPEs of acetic acid and phenol... 

Unfortunately, uncontrolled MLF also presents a risk of wine spoilage by compounds that can produce off-flavours (including acetic acid, volatile phenols and mousiness) or that may be hazardous to human health (such as ethyl carbamate and biogenic amines). The most important aspects of the development of LAB and MLF in wines are dealt with in this chapter. 

DeaxygerMion of phemok. Phenols are converted into urethanes by treatment with phenyl isocyanate using benzene as solvent for both the reaction and crystallization. Hydrogenolysis in acetic acid with Pd/C as catalyst gives arenes in yields of 20-80%. The variation in yield suggests that steric effects may be important. 

Oxiranes can be opened stereo- and regiospecifically under mild conditions with alcohols, thiols, amines, and acetic acid, with simultaneous activation of the nucleophilic and electrophilic centers on an alumina surface.Diols have been obtained on silica gel in the presence of water " and adsorbed FeCls. On an ion-exchange resin, the opening of oxirane isomers to diols and the separation of the latter, ethanolysis, the reaction with phenol,and catalytic ammonolysis have been described. Hydrolysis and methanolysis catalyzed by Nafion-H, a perfluorinated resinsulfonic acid have been reported. ... 

Other acids can be used to promote chlorination or bromination. N-Bromosuccinimide and HBF4 can be used to brominate phenols with high pnra-selectivity, as can pyridinium bromide perbromide, and NBS in acetic acid with ultrasound is effective. The use of NBS with a catalytic amount of HCl has also been reported. Both NCS and NBS with aqueous BF3 gave the respective chloride or bromide. Note that NBS in an ionic liquid gave the brominated aromatic. Bromine on silica gel gave good yields of the brominated aromatic compound. HBr with hydrogen peroxide... 

Water saturated with 2,4,6-collidine 2. 1-Butanol-acetic acid. 3. Phenol-acetic acid-water. 4. 1-Butanol-ethanol-water. ... 

Arylations. Copper(II) acetate catalyzes the reaction of arylboronic acids with phenols and amines (including imidazole and amides) to provide diaryl ethers (e.g., for synthesis of thyroxine) and arylamines, respectively. The reactions are quite erratic, although some preparatively useful cases have been found. 

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