UTILIZATION OF NAVAL STORES CARL F. SPEH Naval Stores Research Division, Bureau of Chemistry and Soils, United States Department of Agriculture, Washington, D. C.
The present outstanding use for turpentine is as a paint and varnish solvent and thinner. The bulk of this volume is used by the applying consumer rather than by the industrial plant manufacturer. Changes in the character of protective coatings, which require new solvents, and improved methods of refining, which make available petroleum products more nearly suited for use as thinners, have reduced the consumption of turpentine by the paint manufacturer. As a solvent for the waxes, turpentine is used, extensively in friction paste shoe polishes as well as stove polishes. As a component of furniture and floor polishes, a substantial volume is consumed. Turpentine is an ingredient, both for its solvent and insecticidal properties, in many of the insecticides on the market. Finally, appreciable quantities of turpentine are used for household purposes. However, it is to the chemical utilization field that we must turn for the development of future industrial uses of this product. Of these, the most important at present is the production of synthetic camphor. Several basic processes are in general use; each is based upon the pinenes, which compose about 92 per cent of turpentine, as a starting point. A method for the production of synthetic camphor with pine oil as the initial material, utilizing the borneol present, is being introduced. Turpentine also serves as the raw material for the production of terpineol and pharmaceuticals such as terpin hydrate and terebene. For every pound of turpentine produced, nearly 4 pounds of rosin are made. Rosin is not only available in larger quantities but it also has a lower market price per pound. Although the standards for turpentine are a t present confined to classifications based upon methods of production, the Naval Stores Act authorized and gave legal status to definite type or color standards for rosin; it definitely prescribed limits for the various grades, which range from X, a pale yellow, to D, a very dark red. The consumption of rosin is in widely diversified fields. The bulk of rosin consumption, however, is in paper size, soap, and varnish. Not only is the paper and paper size industry the largest consumer of rosin (approximately 350,000 to 400,000 barrels annually), but rosin size is today the principal size used in the manufacture of paper. Many paper mills prepare their own size, but in general the mills, other than those using such special methods as the Deltherna process, buy prepared size. Over 275,000 500-pound barrels of rosin are used domestically each year in the manufacture of soaps. Because of the properties ordinary rosin gives to soap, it is generally confined to laundry and industrial soaps, although some is employed in toilet soaps. In the protective coating field the first use of rosin was in cheaper varnishes and gloss oils. Here it was employed either as such or after being hardened by “liming” to neutralize most of the free resin acids. Rosin in its natural state is not a desirable varnish resin because it lacks hardness and water resistance and because its acidic nature causes livering when it is used with certain basic pigments. Combination with alcohols to form esters such as methyl
A,VAL stores, in the broad sense, includes the various kinds of t u r p e n t i n e s and rosins, pine oils, rosin oils and spirits, pine tars and pitches. Of these products turpentine a n d rosin lead in industrial importance. Pine oil and its cqmponents are increasing in importance. The Federal Naval Stores Act recognizes four kinds of turpentine, classified according to methods of production-gum spirits of turpentine, steam-distilled wood turpentine, destructively distilled wood turpentine, and sulfate wood turpentine. The Act recognizes two kinds of rosin-gum rosin and wood rosin.
Classification of Products
Briefly, subjecting the oleoresin exuding from the living southern yellow pine to a simple steam distillation yields gum turpentine and gum rosin. The wood turpentines and rosins are obtained from the pine stumps and the highly resinous, so-called lightwood knots. According to their methods of production, wood naval stores products are further divided : The steam-distilled wood turpentine and wood rosin are obtained from the shredded stumps and knots by steaming and extracting with a volatile solvent; destructively distilled wood turpentine is obtained from a destructive distillation of the stumps and knots cut t o cordwood sine. No rosin is produced by this latter method; instead, rosin spirits and tar oils and pitches are obtained. Both the steam and destructive methods yield pine oils. The fourth kind of turpentine, sulfate wood turpentine, is a byproduct in the production of sulfate paper pulp from pine wood. As an additional by-product in this process a socalled liquid rosin or Tallol is obtained upon acidification of the digester liquors. When dehydrated and clarified, this liquid rosin yields a product with less than 1 per cent of moisture, consisting of about 40-45 per cent resin acids and the balance fatty acids. Attempts are being made t o develop economical industrial methods whereby these two groups of acids can be separated; when available in commercial quantity, the fused resin acids will probably be classed as sulfate wood rosin. Important Uses
Although these types or classes of turpentine and rosin differ in chemical and physical properties, their uses are, in general, interchangeable and no attempt will be made to differentiate between them. I.66
FEBRUARY, 1939
INDUSTRIAL AND ENGINEERING CHEMISTRY
and ethyl abietates is another means of neutralizing the rosin acids. These esters are finding increasing markets as plasticizers and eo-solvents. The glycerol ester of rosin, known to the trade as ester gum, is the most important of these esters. With tung oil this ester gum forms many of the better water-resistant types of varnishes. Ester gum also enters into many synthetic resins; the most important of them are the modified phenolic type resins. Rosin is also combined with some of the modified alkyd-type resins to improve certain properties. Metallic salts (cobalt, manganese, and lead) are formed with the resin acids. These resinates are used as driers. Because of its adhesive and emulsifying properties, rosin enters into the formulas of many insecticides and germicides. Can label cement is made by dissolving rosin in paraffin oil. With castor oil, rosin forms the adhesive of sticky flypaper. Rosin is one of the ingredients of linoleum. It acts as a flame supporter on the heads of matches. Rosin enters into the manufacture of sealing wax, battery seals, phonograph records, rubber cement, handle cement, crack fillers, and cold-set greases. Considerable rosin is used in core oils in foundries. It acts as a stiffener in composition dolls and in box toes and counters for shoes. It is one of the ingredients of a cement for cement-coated nails. It is used to fill the hollow backs of brushes. It forms the core of solder tubes. Among its many other uses are in depilatories to remove hog bristles and the pinfeathers of poultry. When destructively distilled, rosin yields rosin spirits which is used as a solvent and thinner, various grades of rosin oils which are used in foundry cores, greases, and printing inks, and rosin pitches and tars. The latter are employed in brewers’ and Burgundy pitches. Pine oil, consisting of a mixture of terpene alcohols, ketones, esters, phenol ethers, and some terpenes, is a product exclusively of the wood naval stores industry. In recent years great progress has been made in separating these various components and marketing them, each for its particular use. Chief among these are a-terpineol, anethol, fenchyl alcohol, and borneol. At present the chief industrial uses of pine oil are in flotation of lead and zinc ores, in textile scouring, as a solvent in rubber recovery, a cleanser, a disinfectant, and a deodorant, or rather an odorant which serves t o mask unpleasant odors. One of the high-boiling constituents of wood turpentine is dipentene, having a greater solvent value than the pinenes. This is fractionated out and used as a solvent in paints, varnishes, and printing inks where its high solvent power prevents or retards the formation of surface “skins” in-the can before use.
Components With the exception of the production of synthetic camphor and of ester gum, in which the chemical nature or molecular structure undergoes definite change, there has been little change in the industrial utilization of rosin and turpentine since the early days of the industry. However, with knowledge of the components of the crude oleoresin from which the turpentine and rosin are produced and of the fundamental composition of turpentine and rosin themselves, as well as the effect variations in methods of production have on the physical and chemical properties of these components, new uses will be developed. Longleaf (Pinus palustris) and slash (Pinus caribaea) pines are the sources of American gum spirits. An appreciable amount of work has been done by Dupont and his associates in France and by Palkin and associates of the United States Bureau of Chemistry and Soils in determining the com-
167
ponents of the turpentines from these two species of pine. These workers found that American gum spirits of turpentine is composed chiefly of the two isomers-a-pinene and @pinene. It was noted that a-pinene comprised by far the major portion; and on the basis of the few determinations made, a somewhat higher proportion of @-pinenewas indicated in the case of slash than of longleaf pine. This is of interest because of the superior reactivity of @-pineneover a-pinene for certain uses and the fact that the proportion of slash pine to longleaf pine is increasing through reforestation. Palkin is continuing his studies to determine the components making up the 5-10 per cent of the turpentine other than the pinenes. Palkin et al. (1, 3) showed that properly refined steamdistilled wood turpentine consists of approximately 80 per cent a-pinene, with a very small amount of @-pinenein contrast to gum turpentine where the proportion is approximately 1 of P-pinene to 1.75 or 2 of a-pinene. The remaining 20 per cent or less of steam-distilled wood turpentine has been shown to contain camphene but consists largely of monocyclic terpenes, such as dipentine, limonene, terpinene, and terpinoline, and approximately 2 per cent of nonhydrocarbons which consist of various terpene alcohols, some aldehydes, phenols, phenolic ethers, and oxidation and polymerization products. Among the alcohols identified are borneol, fenchyl alcohol, and a-terpineol. Cineole and sobrerol have also been shown to be present. Benzaldehyde is found in very small amounts but sufficient to serve as one of the means for identifying the presence of steam-distilled wood turpentine. A growth in the industrial uses of turpentine should be based upon the use of the components as individuals and upon the use of derivatives of the components rather than the empiric mixture turpentine as such, and such components and derivatives may perhaps form the basis for a group of chemical industries-essential oils, perfumes, and drugsjust as coal tar and its components do for the dye and drug industries. Definite knowledge of the components of the pine oleoresin and of the rosin is even more meager than of the turpentine. The oleoresin on a trash- and water-free basis has approximately 20 per cent of volatile portion (turpentine) and 80 per cent of nonvolatile, consisting largely of resin acids and a small amount of ill-defined neutral products. This fused nonvolatile portion, the residue of the oleoresin after removal of the turpentine by distillation, is the rosin of commerce. Rosin is about 92 per cent rosin acids and 8 per cent neutrals, usually termed “resenes.” Contrary to the generally accepted belief, this mixture of rosin acids is far from being chiefly abietic acid. It is rather a mixture of several acids with a relatively small proportion of abietic acid. These rosin acids differ from the resin acids of the oleoresin before heating. Of resin acids-that is, those present in the original oleoresin-a-pimaric is the most stable. Of the other acids, P-pimaric and sapinic are the least stable. Efforts are being made to convert these less stable acids to more stable form. Fleck and Palkin (9) reported on a rapid method of converting resin and rosin acids by catalytic means to yield so-called a-pyroabietic acid which is highly stable. They subsequently determined that this acid was a mixture of dehydro-, dihydro-, and tetrahydroabietic acids. Since many of the objections to rosin as a raw material are based upon its lack of stability, this more stable form should be of interest to the industrial consumer. Tests of its use in soap manufacture indicate that a white soap containing at least 20 per cent of these pyroabietic acids can be made and that such a soap does not darken on storage. Rosin as it enters commerce is, with few exceptions, a vitreous or noncrystalline substance. Occasionally a barrel
168
INDUSTRIAL AND ENGINEERING CHEMISTRY
of opaque rosin is seen. This property is due to the presence of water or rosin acid crystals. Sometimes the rosin, as such, shows no signs of crystalline opacity. But when used in the manufacture of gloss and core oils or adhesives, the finished product does solidify as a result of the crystallization of the rosin acids. The oil or adhesive is thus rendered useless. Studies are being made to recognize this procrystallizing tendency in rosin and to prevent its occurrence by proper processing. Methods for the production of a noncrystallizing rosin have been the subjects of many patents. The methods usually add foreign substances to the rosin, either as chemical reagents or from pyrolytic decomposition of the rosin. By separating through fractional crystallization the resin acids in the oleoresin, Palkin and Smith (4) produced a noncrystallizing rosin. When available in commercial quantities, this product should be of interest to the industrial user. Color is today the predominating, if not the only, property
VOL. 31, NO. 2
used to grade rosin. Improved methods of production, possibly by modern central stills, of gum rosin will make available more nearly standardized rosin of that type. With the prospect of an increasing rather than a decreasing supply of this raw material and a better knowledge of its properties and components, there should be a wider field of use in many industries.
Literature Cited Am, SOC.Testhg Materials, 37, Part 11, 574 (1937). (2) Fleck, E. E , and Palkin, S., J . Am. Chem. SOC.,59, 1593 (1937). (3) Palkin, S., Chadwick, T. C.,and Matlack, M. B.. U. S. DeDt. Agr.. Tech. Bull. 596 (1937). (4) Pal&, S., and Smith,’W. C., Oil & Soap, 15, 120-2 (May, 1938). (1) Chadwick, T. C., and Palkin, S., Proc.
RECEIVED September 12 1938.
AGRICULTURAL PRODUCTS AS INSECTICIDES R. C. ROARIC Bureau of Entomology and Plant Quarantine, U, S. Departmeqt of Agriculture, Washington, D. C.
N‘JURIOUS insects in the United States are estimated to cause an annual loss of 2 billion dollars. B a c t e r i a and fungi damage crops to the extent of an additional billion dollars. To combat these pests about 100 million dollars’ worth of insecticides and fungicides are used each year. I n the past, arsenicals have been relied upon to control most iniurious insects, and copper and sulfur compounds have been the principal fungicides, but now organic products are used to an increasing extent. Farmers are turning to organic insecticides to avoid poisonous residues of lead, arsenic, antimony, fluorine, selenium, mercury, and other elements on foodstuffs, and also because certain organic compounds are more effective than the commonly used inorganic ones. Organic insecticides may be of natural or of synthetic origin. With the exception of petroleum oils, which may be derived from either plant or animal life of former geological periods, most organic insecticidal materials of natural origin are derived from the vegetable rather than the animal kingdom. Insecticides derived from plants may be divided into three categories: (a) those from crops such as tobacco, (a) those from forest products, and (c) those from weeds, which a t present have no economic value.
Insecticides from Crops Insecticides derived from cultivated plants include nicotine from tobacco, pyrethrins from pyrethrum flowers, and rotenone from Derris, Lonkhocarpus, Tephrosia, Mundulea, and other genera of Fabaceae (the bean family). The farm value of tobacco produced in the United States in 1936 was $250,364,000. From the stems and sweepings from cigar factories and off-grade and refuse tobacco there were produced about a million pounds of nicotine, equivalent to 2.5 million pounds of the commonly used 40 per cent solution sold as nicotine sulfate solution. Nicotine is one of our most valuable insecticides. It can be used as a contact poison, as a stomach poison, and as a fumigant. Nicotine in certain fixed forms-for example, nicotine bentoniteshows promise of becoming a successful substitute for lead arsenate in the control of the codling moth. Pyrethrum flowers were imported into the United States to the extent of 20 million pounds in 1937. Nearly all the world’s supply comes from Japan, but significant quantities are now being grown in Jugoslavia, Kenya Colony, and Brazil. Pyrethrum flowers of satisfactory toxic content have been grown in several localities in the United States. During 1937 the United States imported 570,341 pounds of Derris from British Malaya, the Netherlands Indies, and the Philippine Islands, and 1,591,604 pounds of Lonchocurpus root from Peru and Brazil. These plants contain the powerful insecticide rotenone. An idea of the potency of rotenone may be had when it is realized that as a stomach poison on silkworms it is thirty times as poisonous as lead arsenate, and as a contact poison upon bean aphids it is fifteen times as toxic as nicotine. Goldfish are killed by rotenone a t a concentration of 1 part in 13 million parts of water, but to
