. I.VD USTRIAL AA’D ENGILYEERI,VG CHEJfISTRY
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T’ol. 19, No. 10
Commercial Applications of Chlorophyll Derivatives‘ By F. M. Schertz SOIL-FERTILITY INVESTIGATIONS, BUREAUO F
HE chemistry of chlorophyll is quite involved and has
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many interesting phases, owing to the great number of decomposition products which may be obtained from the green pigments. This paper will be concerned chiefly with the natural green pigment, chlorophyll, and with the pheophytins. “Chlorophyll” as used here is the green pigment as found in living green plants. There are many pheophytins. When the word “pheophytin” is used, the brownish derivative obtained by treating chlorophyll with acid is usually meant. This compound contains hydrogen. When the hydrogen is replaced by zinc or copper beautiful green compounds result, and these compounds will be designated as “zinc” or “copper” pheophytin. They are analogous to chlorophyll and differ from it in that they contain zinc or copper instead of magnesium, The natural pigment (chlorophyll) which contains magnesium is not very stable, while zinc pheophytin is more stable, and the copper pheophytin is the most stable of the three. It is the last compound that is of the greatest commercial importance, because it retains its brilliant green color even when exposed t o light, and it is this compound that is the chlorophyll of commerce. The chlorophyll of commerce is probably all obtained from nettle leaves. Production
It has been estimated that in the United States alone 2 billion tons of dry plant material are produced annually as corn and small grains, and from this more than 6 million tons of chlorophyll are obtained. These figures give us some conception of the amount of chlorophyll present in plant products. “Chlorophyll” has been imported into the United States for - many years. This chlorophyll of commerce is not the magnesium compound, as many are led to believe, but is the copper compound or strictly speaking may be called “copper pheophytin.” Several samples have been analyzed and all of them have been found to contain copper. A few samples marked “pure chlorophyll” and selling a t a high price probably do not contain copper. So far as the writer is informed America has not yet engaged in the preparation of chlorophyll products. From the accompanying table we see that the chlorophyll of commerce costs more than $1.00 per pound. The effect of the World War upon the amount imported is readily observable. Imports of Chlorophyll of Commerce
YEAR 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924
POUNDS 4461 7508 10125 3490 190
VALUE $36S6 8644 8503 3671 192
199 363 8 1248 2761 1881 3213
i63
511 14 2242 3517 1716 5799
35,437
$38,458
...
Total
Uses of Chlorophyll
What becomes of this commercial chlorophyll? Many of us have purchased articles containing it and have never 1 Received
June 8, 1927
P L A N T INDUSTRY, WASHINGTON.
D. C.
known what the coloring ingredient was. I n foods it is used to hide color and bleach cottonseed oil, olive oil, and other seed oils. It is also used as a coloring in various food products. It is the writer’s opinion that the amount used in foods is quite limited. It is very difficult to say just how much of the pigment is u3ed in any one of the industries. It is used to color stearin candles, leather, waxes and resins, pomades and other cosmetic preparations, salves, ointments, vaseline, and to hide the color of mineral oils. I n the manufacture of soaps it is added to hide the ordinary yellow color of the product, to bring back the color to olive oil foots which have become bleached with age or by processing with sulfuric acid, and to give a brighter look or a green color to soap. No doubt much of the color of many soaps is due to the green product resulting from the saponification of the chlorophyll originally present in the natural oils used. Undoubtedly, the bright green compound, copper pheophytin, will find a much wider use in pharmaceutical preparations when its merits are better known and also when a reliable product is prepared. Chlorophyll Pigments
Water-, alcohol-, and oil-soluble products are being sold for coloring purposes. The water-soluble product is a soapy mass containing copper chlorophyllin salt. The alcoholand oil-soluble products usually consist of fat and wax mixed with copper pheophytin. Copper pheophytin is very stable tomi’ard acid and alkali and it is this product that is ground in oil and placed on the market as chlorophyll. The color of a few of these products is brownish instead of green as it should be. Most of them, however, are of a very good grade and quite stable, although their stability varies considerably. The writer has prepared quite pure zinc and copper pheophytin by the methods described by Willstatter and Sjoberg.2 Tests have shown that the zinc compound is inferior to the copper compound. The stability of the copper compound has been tested in various oils, A small portion of the granular copper pheophytin was added to each of several vials containing oil; the vials were stored on a laboratory shelf. The oils used were: crude and refined corn oil, hot- and cold-pressed unrefined peanut oil, refined and unrefined soy-bean oil, cold-pressed unrefined sesame oil, unrefined mustard oil, and cottonseed oil. At the end of two years all the samples retained their bright green color. Copper pheophytin is thus shown to be quite stable in oil solution, even when exposed to light. It may be easily and quite cheaply prepared and has possibilities of being much more widely used than it is a t the present time. Therapeutic Properties Pure chlorophyll exhibits quite marked therapeutic properties. Chlorophyll when freed from the cells is more readily absorbed than when it is present in the cells. When fed t o rabbits the chlorophyll is found in the urine as porphyrin. Chlorophyll in the form of pheophytin possesses a higher bloodforming capacity than iron when given to normal or anemic rabbits. The best results were obtained by giving a combination of iron and chlorophyll. Gastric juice, if allowed to act upon isolated chlorophyll or on the pigment which is * 2. physiol. Chem., 138, 171 (1924)
October, 1927
1-VDUSTRIL4LA N D ENGINEERILVGCHEMISTRY
still present in the leaves. removes magnesium From it and yields pheophytin. Another experimenter has found that chlorophyll acted upon by the gastric juice of a dog forms pheophytin and no pheophorbide. Burgi, who has perhaps done more than any other worker on the biological and pharmacological properties of chlorophyll, has found that chlorophyll is liberated only to a very limited extent when green leaves pass through the intestinal tract. Porphyrin rarely appears in the urine after the ingestion of green foods but always does after ingestion of pure chlorophyll. Chloro-
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phyll has a stimulating effect upon the body cells, it stimulates the hemoglobin-producing cells, increases t,hepower of the heart beat, and reduces blood pressure. Crude chlorophyll, pheophytin, and chlorophyllin all act similarly. Gordonoff has found that chlorophyll fed to dogs has a stimulating effect upon the heart, the intestines, and the uterus, in fact upon all the organs of the body, not merely upon the blood regenerating tissues. Pheophytin may now be purchased in tablet form in most any drug store. T'arious claims are made for the product.
Ammonia as a Source of Nitrogen Oxides for Chamber Acid Plants' Improved practice in the chamber process f o r .ru@uric acid manufacture has resulted jrom the introduction of smaN ammonia oxidation units t o replace niter pots. Considerable economies are realized as a result of the change. By D. H. Killeffer 41!2 FOURTH A Y E . , h-EW
YORK,
s.Y .
a t $9 per ton, a conservative figure) is $6.44, and the necessary labor costs approximately $5 per day. Thus the expense of a discontinuous supply of oxides of nitrogen to such a chamber plant amounts to $35.34 per day of operation, or approximately 47.1 cents per ton of 50' BB. acid made. The total value of the daily output of such a plant is less than $750 and hence the cost of this part of the operation amounts to about 5 per cent of the cost. I n contrast to this situation, the ammonia oxidation process operates continuously with only the occasional attention necessary to regulate gas flow. The process consists in blowing a mixture of air and ammonia gas over a platinum catalyst with suitable arrangements for heat conservation and venting the mixture of air and oxides of nitrogen into the main gas duct. The only raw materials required are ammonia and air and the power consumption is merely that necessary t o put the final mixture into the gas line under slight positive Comparison of Ammonia Oxidation and Niter-Potting pressure sufficient to insure flow without back drafts. A Processes plant turning out 75 tons of 50" B6. sulfuric acid consumes The customary method of introducing the necessary 192 pounds of ammonia per day, costing $12.96 (average oxides of nitrogen into the air-sulfur dioxide mixture going to between 6 and 7.5 cents per pound of NH3), and with a the chambers has been t o allow sodium nitrate (dumped by labor, power, and upkeep cost of only $2.50 per day. Thus the bucketful by hand into the iron niter pots) to react with the supply of oxides to the chambers costs a total of $15.46 60" B6. acid heated by the passing gas stream, which carried per day, or less than half the cost of the same thing when made away with it the nitric acid and nitrogen oxides as formed. from niter and acid. The saving, $19.88 per day, represents The residue of niter cake (sodium hydrogen sulfate) must an economy of 26.5 cents per ton of acid. or about 3 per cent be removed a t intervals to go t o the dump heap or for any of its cost. uhe that may be devised for it. The gas stream thus going The requirement of the reaction in the chamber is a hot through the Glover tower to the chambers should be of as mixture of oxides of nitrogen, sulfur dioxide, air, and water nearly constant composition as possible to insure uniform in the form of steam or a fine spray. Apparently the presence and complete reaction later; and in this respect, particularly, of nitric acid itself is unnecessary and the reaction occurs the "potting" process is faulty. Niter must be introduced through the readiness with which nitrogen in its oxides intermittently into the pots, and unless the intervals between changes its valence. It is quite immaterial whether NO, charges are always very carefully regulated trouble is likely NOs, Nz03, or N20i be admitted to the chamber, since these t o be encountered. Practice in different plants varies seem to be equally efficient in catalyzing the reaction, or somewhat as to the amount of niter used. some using as perhaps rather that they all tend toward the desired KO and little as 3 per cent of the weight of the sulfur burned and others NO2 under the conditions in the chambers. The method by potting as much as 6 per cent. I n general the lower figure which these oxides promote the reaction need not concern i preferred, and on this basis a plant turning out 75 tons of us here. The advantages of the ammonia oxidation process 50" R6. acid per day by burning 31,875 pounds of sulfur of supplying these oxides are: (1) lower cost of raw material would require 956 pounds of sodium nitrate. At the present as compared with niter and acid; ( 2 ) freedom of the resulting market price ($2.50 per hundred) the cost of this is $23.90, gases from such impurities as the halide acids, which tend the cost of the acid required (1430 pounds of 60" BB. acid to destroy the lead chambers and which are always to be exReceived June 20, 1927. pected from Chilean niter; (3) greater regularity and con-
I T E R pots have so long been integral units in so many lead chamber sulfuric acid plants that one is surprised to find them easily and economically replaced by ammonia oxidation units for supplying the essential nitrogen oxide catalyst. Yet already this newest development of heavy chemical industry is effecting decided sayings in operating costs in the chamber acid industry. Installations now in operation are capable of using either anhydrous ammonia or ammonia water to replace sodium nitrate as a source of oxides of nitrogen and have proved themselves capable of paying the cost of the new equipment required out of a year's savings, a thing not to be lightly neglected. I n one 75-ton plant using the new system a reduction of more than 2 per cent in the cost of finished acid is being effected by the change and in smaller plants as great proportional savings can be expected.
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