Phenols sodium periodate

Periodic acid also oxidises phenols, particularly the ortho compounds. Thus catechol gives o. benzyoquione on oxidation with sodium periodate. 

A method developed by Adler et al. (1958) is based on the oxidation of simple phenolic guaiacyl (Adler and Hernestam 1955) or syringyl (Chang et al. 1975) compounds with aqueous sodium periodate solution to ortho-quinone structures in which process nearly lmol of methanol per mol of phenolic hydroxyl group is released [Eq. (1)]. 

Sodium periodate is known to oxidize 2-alkylphenols to the corresponding 2-hydroxycyclohexadi-enones. Phenolic benzhydrol-type coriqxiunds (63) follow a rearrangement pathway under foese conditions, and the results are shown in Scheme 17. The benzylic hydroxy group participates in the periodate... 

Sodium periodate specifically oxidizes guaiacyl groups to quinones. Hydrogen and sodium peroxides in alkali are also somewhat selective in oxidizing lignin and destroy chromophoric groups such as quinones and carbonyl functions while also degrading only aromatic units with free phenolic hydroxyls to dibasic acids. 

Spiro-epoxy-2,4-cyclohcxadienones. Oxidation of ort/io-hydroxymethylphcnols having at least one bulky substituent by sodium periodate leads to spiro-epoxy-2,4-cyclohexadienones in good yield.1 Thus oxidation of 2,4-di-r-butyl-6-hydroxymethyl-phenol (1) in methanol by a slight excess of sodium periodate in water gives (2) in 95% yield. In the absence of a bulky substituent the product undergoes a spontaneous... 

Phenolic oxidation is known to be effected with sodium periodate or periodic acid to yield o- and p-quinols, quinones and other products, depending on substituents attached to the aromatic ring. 2,4,6-Trimethylphenol (221) was subjected to NaI04 oxidation in 80% aq. AcOH to afford the four products 383, 599, 600 and 601 (10, 17, 28 and 31%, respectively). Of these products, the dimer 601 must be formed from the corresponding cyclohexadienone 602 (Scheme 115) °. ... 

SCHEME 115. Oxidation of phenols with sodium periodate or periodic acid... 

This last compound was selectively oxidised at the vicinal diol function with sodium periodate and successively with Jones s reagent, affording the desired acid 8. Direct esterification of compound 8 with dioxy-phenyl-ethanol 14, having phenolic functions protected with benzyl moieties, gave the key intermediate secoiridoid 9. The last step of the synthesis is the stereoselective reduction of 9 that afforded the alcohol 10... 

Phenylphenyl trifluoracetate in carbon tetrachloride upon treatment with ruthenium tetroxide (from ruthenium dioxide and sodium periodate) in carbon tetrachloride during 1 hour gave by cleavage a 9 1 mixture of 4-hydroxybenzoic and benzoic acid in 55% yield. Protection of the OH group is necessary to avoid fragmentation of the phenolic ring (ref.32). 

Treatment of (31) with crotyl chloride-potassium carbonate in DMF afforded (33), which was converted into (34) by heating in a sealed tube. Methylation of the phenol (34) with methyl iodide-potassium carbonate gave (35). Osmic acid-sodium periodate oxidation produced the keto-aldehyde (36). Acetalization by standard methods gave the diacetal (37). Reduction of (37) with lithium in liquid ammonia and subsequent toluene-p-sulphonic acid work-up afforded (38) in a yield of 50 %. A vinylogous aldol condensation was effected with methan-olic potassium hydroxide. The resulting mixture was oxidized with chromium... 

Sodium periodate OxidatiTe cyclodimerization of o-(co-hydroxyalkyl)phenols... 

Sodium paranitro phenolate pKsp 112, 114, 119 Sodium periodate Sodium picrate... 

Dissolve 5 g. of phenol in 75 ml. of 10 per cent, sodium hydroxide solution contained in a wide-mouthed reagent bottle or conical flask of about 200 ml. capacity. Add 11 g. (9 ml.) of redistilled benzoyl chloride, cork the vessel securely, and shake the mixture vigorously for 15-20 minutes. At the end of this period the reaction is usually practically complete and a sohd product is obtained. Filter oflf the soUd ester with suction, break up any lumps on the filter, wash thoroughly with water and drain well. RecrystaUise the crude ester from rectified (or methylated) spirit use a quantity of hot solvent approximately twice the minimum volume required for complete solution in order to ensure that the ester does not separate until the temperature of the solution has fallen below the melting point of phenyl benzoate. Filter the hot solution, if necessary, through a hot water funnel or through a Buchner funnel preheated by the filtration of some boiling solvent. Colourless crystals of phenyl benzoate, m.p. 69°, are thus obtained. The yield is 8 g. 

The distillate may contain volatile neutral compounds as well as volatile acids and phenols. Add a slight excess of 10-20 per cent, sodium hydroxide solution to this distillate and distil until the liquid passes over clear or has the density of pure water. The presence of a volatile, water-soluble neutral compound is detected by a periodic determination of the density (see Section XI,2) if the density is definitely less than unity, the presence of a neutral compound may be assumed. Keep this solution Si) for Step 4. 

Early Synthesis. Reported by Kolbe in 1859, the synthetic route for preparing the acid was by treating phenol with carbon dioxide in the presence of metallic sodium (6). During this early period, the only practical route for large quantities of sahcyhc acid was the saponification of methyl sahcylate obtained from the leaves of wintergreen or the bark of sweet bitch. The first suitable commercial synthetic process was introduced by Kolbe 15 years later in 1874 and is the route most commonly used in the 1990s. In this process, dry sodium phenate reacts with carbon dioxide under pressure at elevated (180—200°C) temperature (7). There were limitations, however not only was the reaction reversible, but the best possible yield of sahcyhc acid was 50%. An improvement by Schmitt was the control of temperature, and the separation of the reaction into two parts. At lower (120—140°C) temperatures and under pressures of 500—700 kPa (5—7 atm), the absorption of carbon dioxide forms the intermediate phenyl carbonate almost quantitatively (8,9). The sodium phenyl carbonate rearranges predominately to the ortho-isomer. sodium sahcylate (eq. 8). 

Sulfates of sodium are iadustriaUy important materials commonly sold ia three forms (Table 1). In the period from 1970 to 1981, > 1 million metric tons were consumed aimuaHy ia the United States. Siace then, demand has declined. In 1988 consumption dropped to 890,000 t, and ia 1994 to 610,000 t (1,2). Sodium sulfate is used principally (40%) ia the soap (qv) and detergent iadustries. Pulp and paper manufacturers consume 25%, textiles 19%, glass 5%, and miscellaneous iadustries consume 11% (3). About half of all sodium sulfate produced is a synthetic by-product of rayon, dichromate, phenol (qv), or potash (see Chromium compounds Fibers, regenerated cellulosics Potassium compounds). Sodium sulfate made as a by-product is referred to as synthetic. Sodium sulfate made from mirabilite, thenardite, or naturally occurring brine is called natural sodium sulfate. In 1994, about 300,000 t of sodium sulfate were produced as a by-product another 300,000 t were produced from natural sodium sulfate deposits (4). 

The chemical resistance of the mouldings depends on the type of filler and resin used. Simple phenol-formaldehyde materials are readily attacked by aqueous sodium hydroxide solution but eresol- and xylenol-based resins are more resistant. Provided the filler used is also resistant, phenolic mouldings are resistant to acids except 50% sulphurie aeid, formic acid and oxidising acids. The resins are stable up to 200°C. Some reeently developed grades of moulding compounds are claimed to be capable of exposure to 300°C for short periods. 

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