Pyrocatechin

Brenz-. pyro-. -apfelsaure, /. maleic acid, -cain, n. Pharm.) pyrocain. -catechin, n. pyrocatechol, pyrocatechin. 

Brenz-holzsaure, /. pyroligneous acid, -kate-chtn, n. pyrocatechol, pyrocatechin. -kate-chingerbstoff, m. pyrocatechol tannin. 

The N,N -dibenzyl-N,N -bis-[2-(3, 4 -dihydroxyphenyl)-2-oxoethyl] -hexamethylene-diamine-dichlorohydrate-monohydrate used as the starting material was prepared as follows 2 mols of chloroaceto pyrocatechin were dissolved in 2,000 cc of acetone and heated to boiling with 2 mols of N,N -dibenzylhexamethylene-diamine for 12 hours, almost the theoretical quantity of N,N -dibenzylhexamethylene-diamine-dichlorohydrate being precipitated and removed by suction after cooling. Excess HCI was added to the filtrate, approximately 66% of the theoretically possible quantity of crude dichlorohydrate of the N,N -dibenzyl-N,N -bis-[2-(3, 4 -dihydroxyphenyl)-2-oxoethyl] -hexamethylene-diamine being precipitated. The product was cleaned by recrystallization from water with the addition of animal charcoal. After drying the substance contained water of crystallization at ambient temperature, MP 206° to 209.5°C. 

The inhibitive efficiency of boric acid polyesters differs greatly. The highest efficiency is exhibited by polyesters of boric acid, aromatic diols and triols. This derives from the fact that in this case the radicals are accepted not only by boron, but also by the aromatic nucleus. Among the aromatic polyesters, most efficient is ester of boric acid and pyrocatechin due to the Frank-Rabinovich cage effect. The efficiency of inhibi-... 

Propylene Tetramer Propylene Tetramer Propylene Trimer Propyleneimine, Inhibited Propylethylene N-Propyl Mercaptan N-N-Propyl-L-Propanamine Prussic Acid Pseudohexyl Alcohol Pyrazine Hexahydride Pyridine Pyrocatechin Pyrocatechinic Acid Pyrocatechol Pyrocatechuic Acid Pyrofax... 

Pterocarya stenoptera DC Feng Yang (Wing nut) (stem, leaf, bark) Salicylic acid, kino-tannic acid, pyrocatechine acid, protocatechinic acid.48-60 Diuretic, used on wounds and ulcers, hemorrhage, suppuration. 

Some readers may conclude that I have it out for JOBO rotary processors. Not at all. I highly recommend them for use with all color processes, C-41, E6, Ilfochrome, etc. They are also fine to use for paper development and negatives larger than 4X5 inches as long as sufficient volume of developer is maintained. They should never be used with developers that contain pyrogallol or pyrocatechin. 

For very low temperature processing a caustic solution of two powerful developing agents, such as amidol and pyrocatechin, may be required, as used in Kodak SD-22. 

Even though it has been in use since 1880 pyrocatechin (catechol) is one of the most overlooked developing agents. The working properties of catechol are very much like those of hydroquinone and it can even be used as a substitute for hydroquinone in many formulae, though it works more rapidly than hydroquinone. 

Pyrocat-HD is a Pyrocatechin/Phenidone-based developer formula that can be used for development in tanks or trays. It is also recommended for JOBO and other rotary type processing in tubes and drums. Although originally meant for sheet film, subsequent use has shown that it is also an excellent developer for use with 35 mm and medium-format films because of its high acutance and tight grain pattern. 

Distilled water (125F/51C), 750.0ml Sodium metabisulfite, 10.0 g Pyrocatechin, 50.0 g Phenidone, 2.0 g Potassium bromide, 2.0g Distilled water to make 1.0 liter... 

Add the pyrocatechin to the warm glycol and stir until dissolved. This should take no more than about a minute. 

Start with about 8.0ml of triethanolamine (TEA) at room temperature and a spoonful of water. Now add 2.5 grams of metol and stir to make a slurry. This is eventually going to make a liter but you can start in a 1/4-liter cup. After the slurry gets a little more fluid, add 15.0 to 20.0ml of some warm propylene glycol. Now you can transfer the metol slurry to the 750.0ml of warm propylene glycol and stir until dissolved. Now add 50.0 grams of pyrocatechin and stir until dissolved. Add 4.0 grams of ascorbic acid and stir until dissolved. Stock B is mixed the same as for Pyrocat-HD. 

The paper developer affects the results. If you develop in glycin or pyrocatechin, the blue tones will be lighter. Any developer that produces a brownish color by direct development is good for... 

Most of the chemicals used in black and white processes are safe and biodegradable. A few, such as selenium, pyrogallol, pyrocatechin, sodium hydroxide, and hydrochloric acid, require careful handling and disposal. Throughout The Darkroom Cookbook specific warnings and instructions will be given where appropriate. 

Unless a formula specifically calls for distilled water, in most cases tap water can be used. Even when distilled water is indicated, good quality, filtered tap water will usually suffice. A notable exception is those formulas which call for the use of pyrocatechin (catechol) or pyrogallic acid (pyro or pyrogallol). 

Notes Pyrocatechin is easily soluble in warm water. It is chemically akin to hydroquinone but with special properties, notably the feet that it oxidizes readily and its oxidation products have a tanning effect upon gelatin. 

All developers containing pyrocatechin should be mixed with distilled water, whether or not the formula calls for it. 

Dilute pyrocatechin developers will typically provide a speed increase. 

Distilled water at 125F/52C, 750.0ml Sodium sulfite, 0.3 g Pyrocatechin, 2.0 g... 

Time-temperature development chart for low-temperature developers. This chart shows time-temperature for low-temperature developers labeled as follows (l) Kodak SD-22 Amidol-Pyrocatechin, no glycol (2) Kodak SD-22, 25% glycol (3) Kodak SD-22, 50% glycol (4) Kodak D-8, no glycol ... 

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