Catecholates

C. It is secreted along with noradrenaline by the adrenal medulla, from which it may be obtained. It may be synthesized from catechol. It is used as the acid tartrate in the treatment of allergic reactions and circulatory collapse. It is included in some local anaesthetic injections in order to constrict blood vessels locally and slow the disappearance of anaesthetic from the site of injection. Ultimately it induces cellular activation of phosphorylase which promotes catabolism of glycogen to glucose. 

Phenol, 0-, m- and p-cresol, catechol, resorcinol, hydro-quinone (and other nuclear substituted phenols), 1 - and 2-naphthoi... 

Dissolve a few crystals of phenol in water and add ferric chloride solution a violet coloration is produced. Repeat, using i 2 drops of m-cresol shaken up with about i ml. of water a violet coloration is again produced. Catechol (in dilute solution) gives a green coloration. 

Phenol, CgHjOH, catechol, <3 CjH4(OH)2, resorcinol, m C3H4(OH)2,... 

Azo-dye formation. Dissolve 2-3 drops of aniline in 1 ml. of cone. HCl and add 3 ml. of water. Shaike to dissolve any hydrochloride which may have separated and cool in ice. Add a few drops of 20% sodium nitrite solution. Add this cold diazonium solution to a cold solution of the phenol in an excess of aqueous NaOH solution. Solutions or precipitates of azo-dyes ranging in colour from orange through scarlet to dark red, according to the phenol used, are obtained. Note in particular that i-naphthol gives a brownish-red, 2-naphthol a scarlet precipitate. Catechol decomposes. 

Action of bromine water. To a concentrated aqueous solution of the phenol or to the phenol itself, add bromine water gradually. At first the bromine is decolorised and then on adding an excess a white or yellowish-white precipitate of a polybromo-derivative is produced with all except catechol, hydroquinone, i- and 2 naphthol. 

On adding i drop of bromine water to catechol, a deep red coloration is produced immediately. On gradually adding bromine water to a solution of hydroquinone, a deep red coloration is produced, followed by the separation of deep green crystals which then dissolve giving a yellow solution, i- and 2-Naphthol will decolorise hromine water, but usually no precipitate of the bromo compound can be obtained. 

Green coloration. Catechol (colour rapidly darkens). [Aniline (pale green), o-toluidine (pale green initially), mono-methylaniline, and diphenylamine, each in dil. HCl.]... 

TEST Phenol Resorcinol 1 Hydro-Catechol 1 quinone e-Cresol m-C resol p-C resol i-Naphthol 2-Naphthol... 

Benzaldehyde is easily oxidised by atmospheric oxygon giving, ultimately, benzoic acid. This auto-oxidation is considerably influenced by catalysts tiiose are considered to react with the unstable peroxide complexes which are the initial products of the oxidation. Catalysts which inhibit or retard auto-oxidation are termed anti-oxidants, and those that accelerate auto-oxidation are called pro-oxidants. Anti-oxidants find important applications in preserving many organic compounds, e.g., acrolein. For benzaldehyde, hydroquinone or catechol (considerably loss than U-1 per cent, is sufficient) are excellent anti-oxidants. 

That aqueous layer that was saved can be removed of most of its water by vacuum distillation, allowed to cool slightly then extracted with hot toluene. When the toluene cools, a few hundred more grams of catechol will crystallize out but will be contaminated with some heavy red bromo compounds. The crystals are filtered and vacuum distilled such that the pyrocatechol will distill over first, leaving the higher boiling bromo compounds behind. Yield is about 80% or 600g of catechol. 

METHOD 3 [109]—1 part guaiacol and 2.5 parts MesSiSNa in 1,3-dimethyl-2-imidazoline heated at 185°C in a sealed pipe bomb gives 80-96% catechol. 

METHOD 4 [110, 111] - guaiacol and cupric perchlorate (Cu(CI04)2)-ascorbic acid (that s vitamin C, bubba ) are mixed in an appropriate solvent under oxygen atmosphere in a flask to give about 30% catechol. 

METHOD 1 [112l-5g phenol in dH20 is stirred 5 hours at 20 C with some ferric sulfate (Fe2(S04)3, an additional 7mLs dH20, 13mLs 6% H2O2 and a pinch of aluminum oxide (AI2O3). Yield of catechol is 2.5g (50%). 

METHOD 2 [113]-Phenol can be oxidized with either performic, formic or acetic acids to catechol. For example phenol, formic acid, concentrated H2O2 and polyphosphoric acid are heated 2 hours at 80 C to give 53% catechoi. Addition of phosphorus pen-toxide (P2O5) is said to increase the yieid. 

METHOD 3 [114]-Phenol and 30% H2O2 in molar ratios of 10 3 to 10 8 is heated at 70 C for 8-10 hours to give -15% catechol. Addition of tert-butyl alcohol increases the yield. 

METHOD 4 [115]-80% phenol in aqueous H2SO4 soiution of pH 3 is brought to 50 C. 30% H2O2 is then added causing an exothermic reaction and a temperature of 15 C over 3-4 minutes time. 6% aqueous H2SO3 is added after 4.5 minutes, the solution quickly cooled and extracted with isopropyl acetone (Strike would think that another solvent like methyl ethyl ketone could be used) to give 60% catechol. 

One of the problems with all the current phenol conversions is that a certain amount of other phenols, such as resorcinol and hydro-quinone, will be formed along with the catechol (don t ask). These species are very hard to separate from the catechol because they are all so similar. Aside of carefully monitored fractional distillation there are some vague strategies which can be found in the Chemical Abstract references 116-118. 

The reaction itself works by the action of Na or K from NaOH or KOH which form what is called a catechoxide dianion with the two OHs of the catechol species. This makes the two ripe for an attack by a methylene halide which can be either DCM (methylene chloride, or dichloromethane), DBM (methylene bromide, or di-bromomethane) or DIM (methylene iodide, or diiodomethane). DCM is cheap and works pretty well, but DBM and DIM work better yet are more expensive. 

When doing this method the scientists confirmed something that has long been theorized by those who study these sorts of things. That is, they determined that if one tries to convert all of the catechol at once like was done in the above method then it tends to form a dimer side product like that shown below [120]. 

Catechol - 11 Og, smells like hospital toilets from where I m sitting. Easy and cheap to purchase. Use a funnel to get this into the flask and don t try to dissolve it first as it just sticks to everything, a dry funnel and add slowly so as not to stop the stirrer bar. When this is added the solution will start to change to a dark greeny colour. It is important that the stirrer keeps spinning, if it all stops moving in there, some bits can get left out of the reaction, and your yield will suffer. 

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