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Get From recovered by condensing the vapors formed during the destructive distilla- tion—heating to a high temperature in the absence of air—of lightwood. Turpentine Sulfate turpentine is recovered as a byproduct during the conversion Leo A. Goldhlatt of wood to paper by the sulfate process. Several hundred different com- pounds with the formula CmHtn can theoretically exist. Only half a dozen, Turpentine is a volatile oil that con- however, are present in appreciable sists primarily of a number of terpcne quantities in most commercially avail- hydrocarbons having the general for- able turpentines—a-, jß-pinene, mula GioHno. It is obtained by distilling camphcne, A'^-carene, dipentene, and the exuded by or contained terpinolene. The molecular configura- in the wood of certain species of tion and some of the physical charac- trees. The formula means that the in- teristics of those are shown in dividual molecule of each of the tcr- the chart opposite. penes contains 10 atoms of carbon and 16 atoms of hydrogen. The 26 atoms THE FOUR KINDS of turpentine dif- may be arranged differently in some fer in composition, and different molecules, thus constituting different samples of the same kind of turpentine terpenes. may difi^er materially in composition. The United States produces well The composition of gum turpentine over half of the total world supply of may vary with the species of tree from spirits of turpentine. Federal laws regu- which the oleoresin was derived, but lating its designation have been en- turpentine obtained from the same acted. The Federal Act, species, or even from the same tree at passed in 1923, recognizes four kinds difiPerent times, may differ somewhat of turpentine classified according to in composition. Steam-distilled wood methods of production—gum spirits of turpentines may difi'er in composition turpentine, steam-distilled wood tur- with the w^ood used by the processor or pentine, destructively distilled wood with the techniques and operating con- turpentine, and sulfate w^ood turpen- ditions used in their production. Such tine. differences within any specific class of Gum turpentine (gum spirits) is turpentine are generally rather small. made from the gum, or oleoresin, col- Before refining became lected from living trees. Steam-distilled an industry, turpentine was used ex- (S. D.) wood turpentine is obtained tensively as an illuminating oil. Its out- from the oleoresin within the wood standing use now is as a . Just a (scrap w^ood, knots, or stumps, and half century ago, when only about a other wood waste, commonly called dozen were available for com- lightwood) by steam of mercial use, turpentine reigned su- the wood or of an extract of the wood preme. But the American chemical in- with a solvent. Destructively distilled dustry has developed more than a hun- (D. D.) wood turpentine is obtained dred commercial solvents to challenge by fractional distillation of certain oils the supremacy of turpentine. The suit-

002722°—51- -58 815 8i6 50-1951 YEARBOOK OF AGRICULTURE ability of a solvent for a speciñc pur- leuin products more nearly suited for jDosc often is determined by many fac- use as thinners, have reduced the use tors other than solvent power. De- of turpentine by manufacturers. velopment of synthetic solvents has Turpentine is used as a solvent in nibbled away at turpentine's markets; many industries. As a solvent for , replacement of older products with it is used extensively in friction paste newer synthetics has removed other shoe polishes, stove polishes, furniture markets; and the competition from and floor polishes, liquid floor , and cheaper petroleum and coal- sol- wax auto polish, in modeling and vents has made heavy inroads on still grafting waxes, and in drawing cray- other uses of solvents for which tur- ons. It is an ingredient of wood filku's pentine might be preferable but not and w^ood stains. It is used in ceramic so superior as to warrant the difference work for application of colors and as a in price. Further, the petroleum indus- lubricant in grinding and drilling glass. try has developed products that have A small amount is used for medicinal even greater solvent power than tur- purposes, both alone—as an antiseptic pentine. or an anthelmintic, for example—and in prepared drugs, liniments, and j^har- THE LAYMAN almost always asso- maceuticals. Many insecticides contain ciates turpentine with paint. Master turpentine for its solvent and insect- ])aintcrs generally consider turpentine killing properties. a better paint thinner than petroleum Home owners use a great deal of tur- products, cs]3ecially for outside white pentine. In fact, less than a third of the house , because, they believe, turpentine used in the United States is turpentine makes paint more durable reported as "industrial consumption'*; and easier to work under the brush. most of the rest, listed as "not ac- Although all chemists do not agree on counted for," is distributed over-the- the point, many think that turpentine counter through retailers who are not has an advantage. The solvent and covered by the surveys and is used as wetting properties of turpentine are a paint thinner by painters and prop- generally regarded as superior to those erty owners. of straight petroleum sohents. The importance of the over-the- Few exposure tests of the effect of counter market to the pine gum farmer paint thinners on tiie durability of is apparent when one considers th(^ rel- coatings have been reported. Certain ative proportion of gum and wood tur- weathering tests on exterior white pentine used industrially. In 1949-50, house paints reduced with different the production of gum spirits in the types of volatile thinners, however^ United States was 323,010 barrels of have shown that turpentines contribute 50 gallons each; the production of slightly more to the durability of paint wood turpentine of all types amounted coatings than do mineral spirits. Tur- to 350.280 barrels. That year we used ]Dentine has long been used as a solvent 555,636 barrels, of which'112,442 bar- and thinner for ]:>aints and . rels were reported to be "industrial That is still by far its major use^ but consumption." However, of this indus- this use has not kept pace with the trial consumption, only 11,991 barrels greatly increased jDroduction of the were gum turpentine and 100,451 bar- paint,, ^ and industry. rels were wood turpentine. Thus, The bulk of the turpentine so utilized nearly 30 percent of the w^ood turpen- is used by contractors, indi- tine, but only about 4 percent of the vidual painters, and property owners. gum turpentine, produced in the Changes in the character of protective United States in 1949-50, went into coatings, which require new solvents, "industrial consumption." and improved methods of refining pe- Gum turpentine competes with troleum, which make available ])etro- wood turpentine for the over-the- CHEMICALS WE GET F R O ]M TURPENTINE 817 counter market. Both kinds arc meet- by reason of the low yields obtained, ing increasing competition from the even though turpentine was then avail- petroleum industry, which has devel- able at 35 cents a gallon, a fact that oped new and improved refining tech- influenced the initiation of the venture. niques and modern merchandising Another attempt was made during thc^ methods. These petroleum products First World War, again a period of are cheaper than turpentine and price low-priced turpentine and high-priced is a potent factor in this market. It is^ natural . When the war ended therefore, to the chemical-utilization turpentine prices went up and the field that we must turn for the develop- price of natural camphor was pegged ment of future uses for turpentine. by the Japanese Camphor Monopoly Turpentine must be regarded as a Board. So the factory was shut down source of chemicals. Markets that have for good. In the 1930's the E. I. du been lost because of the research by the Pont dc Nemours & Co., an important aggressive, technically m.inded organic- user of camphor, wishing to be inde- can be regained by pendent of the Japanese camphor mo- equally aggressive and imaginative re- nopoly, undertook the manufacture of search by the . synthetic camphor from turpentine. The process this company initially de- THE CHEMISTRY of the terpcncs, of vejoped was subjected to continuous which turpentine is the most plentiful research, modification, and improve- source, is fascinating. Literally hun- ment. Although accurate figures are dreds of chemical derivatives have been not available, it is gentu^ally believed prepared from the terpenes, and thou- that by December 7, 1941, consump- sands of articles have been published tion of synthetic camphor exceeded in scientific journals on thc^ behavior of that of natural camphor. this unusual class of chemically reactive This industrial development was in- compounds. Several Nobel Prize win- itiated in periods of low-priced turpen- ners have explored this field. One of tine. It declined when prices were high. them, Otto Wallach (1847-1931), In 1920, the price of turpentine rose was awarded the prize specifically for to $2.33 a gallon; it was less than 20 his work on the chemistry of the ter- cents a gallon in 1938 and was $1.50 penes. These researches have been pri- in 1946. Such fluctuations in the price marily of academic rather than indus- of a raw material are a SCTíOUS deter- trial interest. Most of the compounds rent to the allocation of research funds that were prepared have remained lab- for the development of new uses. The oratory curiosities; hardly a dozen have manufacturer must consider the possi- attained the production level of a mil- bility that, even if the research is tech- lion pounds a year, often considered by nically successful and a promising new the chemical industry as the turning product is developed, rising costs for point between successful and unsuc- his raw material will necessitate such cessful development. Yet only a decade increased prices for the new product ago but one strictly chemical use of that it cannot successfully compete turpentine had gained that enviable with products already on the market. status—the synthesis of camphor. The Isoprene is a case in point. Isoprene field is wide open to research. is chemically related to turpentine. In The earliest successful efforts to use 1860 it was observed that isoprene, a turpentine as a chemical in an indus- hydrocarbon with the fornmla Cr,Hs, trial-chemical process was in the manu- could be obtained during the destruc- facture of synthetic camphor. Even this tive distillation of rubber. Many at- was not without its failures, however. tempts were made to reverse the proc- The first commercial attempt to manu- ess and make synthetic rubber out of facture camphor in the United States, isoprene. Turpentine, because the ter- at Niagara Falls in ] 900, failed, chiefly penes that compose it have the formula 8i8 19 5 0-1901 YEARBOOK OF AGRICULTURE Ci„Hir>; was obviously a possible source mcrized further to terpinolenc (IV), for the desired isoprene, and numerous and terpinolenc in turn to experiments on making isoprene from (V). There are many ways of pro- turpentine were eonducted. ducing these isomerizations, but it is During the Second World War. effi- often difficult to control the extent of cient processes were developed for the isomerization. Terpinolenc and ter- production of isoprene from turpen- pinene are useful as solvents, but they tine, and methods were devised for pre- are also very reactive chemically. They paring high-quality synthetic rubber react with such diverse chemicals as from it. Large quantities of isoprene maleic anhydride, and sulfur- were made froin turpentine at moder- containing compounds, phenols, form- ate cost, but after OPA ceilings were aldehyde, halogc^ns, and oxygen to removed the price of turpentine rose to j^roduce materials suitable for indus- Sl.v'30 a gallon. At that price, isoprene trial-chemical application. For ex- from turpentine could not compete ample, reaction with maleic anhydride with petroleum, which cost less than a is the basis for the commercial pro- tenth as much. The plant producing duction of acids used in the manufac- isoprene from turpentine was shut tuiT of varnish , paper coatings, down. Several million pounds of iso- printing , and masking tapes, and prene arc now being made annually some of the sulfur-containing com- from petroleum, even though its puri- pounds have found use as lubricating- fication is more difficult than w^ould be oil additives. the purification of isoprene from tur- Furthermore, dipcntene (III) itself j^entine. If a reasonably stable price of reacts with many chemicals to form 30 to 40 cents a gallon for tur]:)entine useful products. For example, wqth could have been maintained, the de- phenol it reacts to produce menthyl velopment might have been différent. phenol, which has found use as a stabi- One way to illustrate the variety of lizing agent for ethyl cellulose. It may chemical reactions of which the ter- be polymerized to produce high-melt- penes are capable and to indicate some ing hydrocarbons, or conversely it may of their possibilities is by means of a be "cracked" to produce isoprene chart, like the one opposite. It show^s (VI). Still again, dipcntene rna)' be only a few of the reactions of a-pincne dehvdrogenated to produce /;-cvmene (I) and /9-pinene (II), which might (Vfl). be considered of interest for industrial /;-Cymcnc has exceptionally strong application. /?-Pinene can readily be solvent properties and is capable of a converted to a-pin ene, but the reverse host of chemical reactions. Like any reaction (the conversion of a-pinenc to aromatic compound, it may be chlori- /?-pinene) is not feasible. Conse- nated, nitrated, sulfonated, and oxi- quently, any product that can be made dized. Chlorinated /;-cymene has been from cc-pinene can also be made from considered for use as a wood preserva- /5-pinene ( although the reaction mech- tive and as an insecticide, Sulfonation anism is not necessarily through prior provides a route to thymol (VIII), conversion of /5-pincne to a-pinenc). itself useful as a pharmaceutical and The converse is not true, however ; cer- from which menthol can be obtained. tain chemical reactions are peculiar to Nitration leads to nitrocymenes and /5-pinenc. thence to amines which have been con- Both a-pinenc and ^-pincnc can be sidered for use as dye intermediates and readily converted (isomcrized) to di- as antiknocking agents for automotive pentene (III) by a variety of methods. fuels. Dipcntene itself has many uses—for Oxidation of /;-cymcne, most eco- example, as a solvent or antiskinning nomically with air, leads to a series of agent in paints or as a rubber reclaim- interesting compounds. Cumie acid ing and processing aid. It may be iso- (IX) is similar to benzoic acid^ can be CHEMICALS WE GET FROM TURPENTINE 819 A few reactions of a-pinene (I) and /S-pinene (II) Of Interest for Industrial Application

COOH COOH I ÇH3 CH3 HcAcH Hc/%„ h I II - I II Mini I 11 HC ^CH HC ,CH \c/ I I I CH CH COOH CH HaC \H3 HjC^ \H3 I TEREPHTHALIC ACID o.TERPINENE CUMIC ACID P-METHYL ''l|||, P.METHYL STYRENE ACETOPHENONE ''lli,, """"■ »"«'^"■^

ÇH, ÇH3

HSÇ^^\H HC/'\H HC XH c/%. Tl I Tl ^" "il """'■^^ I IV I II V'" I !|{iiiiiiiiiiiiiiiiiiiiiiiiiiiiii II V" I iiiniiiiiiiiii iiiiiiiiijlli' XI iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii||i' XIII HjC CHj HC^ COH -HC CH- HC^^^CH- - HC^^CH ^c/ \/ I I r I /\ «II /^ CH COH Cv H}Ç CHj H3C CHS H3C' \H3 H3C^ CH3 HaC^ CHJ TERPINOLENE P-CYMENE DIMETHYL TOLYL DIMETHYL STYRENE CARBINOL

CH3 CH3 HsC—CHjOH HC „, n V' '"' ' Ill,,,,,, HSC '"«lllllli,, A HJC CH XIX CH ISOPRENE POLYMERS 'llljllllllllllHIIIIIIIIIIIIIIIIIIHIIini HC''^ ^CH MENTHYL PHENOL illllllllllllllllllllll HjC II XV I CHJ H3I HC^ «3 HjC yCH2 ^CH 11111,11, CH H3C CHs CHs o*i;,iii NOPOL H3C CH3 Uli' II S 'C, « DIPENTENE yC\ ,,111111 ALLO-OCIMENE HC/,\H HC' II CHo HYDRATE'lllllllllllll \CH, II ETHERS i|| illllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll y Hsf CH 'l||{lllllllllllllllllllllllll|{ H3C I XVIIIII H3f CHs MALEIC RESINS'l|||lllllll HJC CHJ H2C, HjC^ CHJ OIL ADDITIVES'III lllllllllllll \ / / CH CH CH ' a-PINENE ß-PINENE "•v H3C CH3 '"" &"H

CH3 Ulli: I, HJÇ-CCI3 ( :H œj 'ill A HjC CH / \ HjC^ ^CH HI < XVII XVI III CAMPHOR ( HS HsC^ /CHs HjC^ ^CHj CHLORINATED /"3 CH ( ||r THIOCYANOACETATES I f CCI /\H, H3C CH3 ^\:H H3C CH3 7.TRICHLOROMETHYL. a. CAM PHEN E B-CHLORO- A'-P-MENTHENE 820 1950-19 5 1 YEARBOOK OF AGRICULTURE substituted for bcnzoic acid for several thetic camphor or chlorinated to pro- uses, and may replace that acid in duce chlorinated camphene (a widely many applications. Tercphthalic acid used agricultural insecticide, especially (X) has been used in the production against cotton infestations), or it may of plasticizers and resins for protective be converted into a complex thiocyano- coatings. A potentially huge market for acetate derivative sold extensively as a this acid exists in the production of household insecticide and cattle S])ray. synthetic fibers such as the Terylene of a-Pinene may be hydra ted to a-tei^- British manufacture, or the du Pont pineol (XVII), w-hich finds use in per- Company's Fiber V. fumes, particularly soap perfumes Oxidation of /;-cynii^ne with air since it is resistant to alkalies and has a under other conditions leads to di- sweet odor suggesti\e of lilacs, and has methyl tolyl carbinol (XI) and methyl many industrial applications, such as acetophenone {XII). The carbinol a dénaturant for alcohol, a delustc^rant (an alcohol) has solvent and wetting for rayon, a disinfectant, and a pre- iDroperties like those of j:>ine oil. It is a servative^ for casein and animal glue. mild disinfectant and has a pleasant Sc\'eral other useful materials not indi- odor resembUng that of sw-eet clover. cated by the structural formulas in the It may be dehydrated to dimethyl chart are prepared from a-pinene. siyrene (XIII). This comjDOund can These include synthetic pinc^ oil, exten- be polymerized, or coi^olymerized with sively used in such diversified fields as styrcne, to give resins that appear to disinfectants, industrial detergents, tex- have commercial possibilities. Alter- tile chemicals, and mineral ore con- natively, it may be rt^acted with phenol centration, terpin hydrate used as a and resinified to a phenolic . The pharmaceutical, terpenc ethers used as other jjroduct obtained simultaneously solvents, sulfurized compounds used as during this oxidation of /;-cymene to additives for mineral oils, and maleic dimethyl tolyl carbinol is methyl ace- anhydride resins used in the protec- tophenone (XII), which can also be tive- and papei-coatings industry. obtained from the dimethyl styrene The chemical utilization of /i^-pinenc (XIII). It finds use as a soap perfume (II) is of still more recent origin. As and may be converted to /;-mcthyl indicated earlier, it can be converted styrene (XIV), which, in tui'n, may be to a-pinenc ; so all the products obtain- polymerized to tough colorless resins. able from «-pinene can also be obtained Reverting again to a-pinene (I), from /i-])inene. And it also undergoes simple heating for a short time (a frac- a number of reactions peculiar to /i- tion of a second) at a high temperature pinene. It can be polymerized to a (450° C.) causes it to isomerize to allo- relatively high melting hydrocarbon ocimen(^ (XV). This compound is of resin that is finding extensive industrial s]3ecial interest chemically because of application in a wide variety of fields, the unusual structure of its molecule— a use that may eventually rank with three sets of alternate double- and sin- the leading chemical uses of turpen- gle-valence bonds arranged in an open tine. /íí-Pinene may be converted to chain. Literally dozens of products as myrcene (XVIII), which is capable of diverse as resins, solvents, and perfum- polymerization to synthetic rubber and ants have been prepared from allo- from W'hich numerous chemical de- ocimc^ne but so far with little, if any, rivatives may be prepared. Reaction commercial success. with formaldehyde loads to the forma- Under still other conditions a-pinenc tion of Nopol (XIX). an alcohol sug- can be isomerized to camphene (XVI). gested for use as a solvent and for the This isomerization is carried out com- preparation of plasticizers and a va- mercially on a very large scak\ The riety of novel terpene derivatives. camphene so obtained is generally not A final example of the diversity of used as such, but is converted to syn- reactions of which these terpencs are C H E ]^J I C A L s WE GET FROM TURPENTINE 82I capable is the simple reaction with car- oil additive—or to produce still other bon tetrachloridcj familiar to all as a compounds, household solvent and fire extin- guisher, to form the compound (XX) LEO A. GOLDBLATT is a graduate of to which has been assigned only the Clark University and the University of chemical name 7-trichloromethyl-8- Pittsburgh. A principal chemist in the ch]oro-A'-y;-menthene.Thiscompound^ Bureau of Agricultural and Industrial which can be obtained in excellent Chemistry, he is engaged in research yield by a very simple process, has in- on the composition, properties, com- secticiclal properties and may be useful ponents, and derivatives of naval as a flameproofing material or as an stores.

THE SOIL Conservation Service Research Branch and the Purdue Agricul- tural Experiment Station in Lafayette, Ind., made a study of wheat straw grown on experimental watersheds, which are on prairie soils of high native fertility but were at a moderate state of depletion when the experiments were started in 1940. The following analysis of values is based on the study. Wheat grown under a prevailing system (low rates of fertilization in a 3-year rotation of corn, wheat, and mixed meadow) had the following quantities of the main fertilizer components per ton of straw: Nitrogen (N), 12.4 pounds; phosphate (P2O5), 26.0 pounds; potash (K.O)^ 19.2 pounds. These were worth, at 1950 straight fertilizer prices, $1.43, $2.16, and $0.99, respectively. Each ton of straw in the prevailing system has contained $4.58 (more or less) worth of nitrogen, phosphorus, and potassium. The straw left on the land has had a fertilizer value between $6 and $9 an acre. Wheat grown on adjacent areas under an improved system (high rates of fertilization and moisture conservation) with the same rotation contained the following quantities of the main fertilizer components per ton of straw: Nitro- gen, 19.4 pounds; phosphate, 34.4 pounds; potash, 38.8 pounds. They were worth, respectively, $2.23, $2.86, and $2.00. Each ton of stra^v in the improved system has contained $7.09 (more or less) worth of nitrogen, phosphorus, and potassium. The straw left on the land had a fertilizer value between $15 and $18 per acre. Mineral nutrients in straw other than nitrogen, phosphorus, and potassium may have small fertilizer value. Although difficult to evaluate, there are prob- ably benefits to the soil as a result of returning strawy residues to the land through greater nitrogen fixation by legumes in the meadows following wheat, additions of organic matter, and improvement of soil structure. The damage done to meadow seedlings by wheat straw is often overemphasized and may be minimized by a high fertility level in the soil and caution in combining and spreading the straw. Before selling, it is wise to consider the value of straw for soil maintenance and the costs of harvesting and marketing. The approximate cost of raking, baling, and hauling to market in central Indiana is about $6 a ton. The sale of straw may add to the immediate cash income of a farming enterprise, but it is an unprofitable action unless the selling price covers all costs and assures a reasonable profit.—H. A. Jongedyk and R. B. Hie kok. Soil Conservation Service.