Ursinus College Digital Commons @ Ursinus College Chemistry Honors Papers Student Research 5-26-1947 Synthesis of Terpenes Jeanetta Reneberger Follow this and additional works at: https://digitalcommons.ursinus.edu/chem_hon Part of the Chemistry Commons Click here to let us know how access to this document benefits ou.y Ursinus College Library, URSINUSIANA COLLECTION Class_0_ Box(^{U^.-% Synthesis of Terpenes Jeiinetta Reneberger Department Honors Ursinus College May, 1947 This paper is submitted in partial fulfillment of Department Honors. Group Adviser Introdxiction Terpenes are organic compounds having the empirical formula (Q.Hji) , They are the essential oils which early chemists extracted from the leaves, flowers, resins, bark, and roots of many plants. These volatile perfume materials were called the "essence". Isoprene, obtained by distillation of caoutchouc (india rubber), is the -narent hydrocarbon from which all terpenes are derived. Many plants produce isoprene and condense it through either linear or cyclic polymerization into terpene compounds. These in turn oxidize, hydrolize, or reduce to form many familiar products. A few terpenes are solids, hut most are volatile liquids^having boiling points between 155** smd 1R5°. They are §^'^^Mft from their natural soiirces by steam distillation and by extraction with organic solvents. Terpenes incliide both open chain compounds and cyclic compounds having one and tvro rings. They are very active sub• stances, and have a complex chemistry. Addition react'-ons are common, for they are generally unsaturated; they polymerize readily. Terpenes are easily oxidized; they combine with ozone, and show the general characteristics of compounds containing double bonds. All terpenes are practically insoluble in water, but they are readily soluble in the ordinary organic solvents. Many industrial products are made from terpenes and their derivatives. They are used extensively in perfumes, flavors, paints, varnishes, plastics, and medicines. Terpenes are of great use in chemical study, for they form the link between simple organic structures and complex natural products. Classification All terpenes have the empirical formxila CoHn- or some multiple of it, Hemiterpenes have the empirical formula G^Eg, They include the parent of all terpenes, Isoprene C M,. = CM CH -Chi. The true terpenes of formula C,^H,^are represented by terpin sylvestrene CM, MC ^-«-^^..„3 Sesquiterpenes, having the formula C,^ H^,, inclixde farnesol CH^CH^ T-'CH *H^CH^ T'CH^HX* »^ nerolidol CH, ^^H^^H^ Diterpenes, having the empirical formula, C ^.^fL ^j^, include among their representatives the common compovmd vitamin A -'^'^ i^^tMCH^cni^CMeH.oH H,C c Polyterpenes, which contain 25 or more carbons, are represented crt '""^ "^"^ squalene ^ • AH.H.C- CH CH, CH,.: = en JH. «H C = CHCH^CH.C = t MCM^cHjC = cHcHi ^ cHj CH, carotene ^M, ,CH, ^'^ . ,„e.= CHCH--CM e - tHCH=CMCH ^CCH=<LHCH =CCMr«.H C ^ \ <rt, ^t"^ Terpenes are classified also according to their degree of saturation. Their are open-chain, mono-, di-, and tricyclic terpenes. Examples of open-chain terpenes are linalool - M3 c - -HCH.cH, .0 M CH^ alpha gerani«l "\H..H.C M J^HCH.^H myrcene CH^ e. -1 H c H^CH*. c CH = c H^. Examples of monocyclic terpenes are soherol ^.H, • MC -'^"^ ' aril, ^ H; '^H> paracymene «.iu nr*^^ ^ cM H C ,1 Ht V r SH^cHCHi The parent bicyclic terpenes are CH. thui ane ^\L H,rC i u tHjCrtcH, carane in... Hit C rt;cm. Hit.,^1 ^'•I ^ H pinane Hit — r>trA H^c , cHi "— t - H camphane C Hj Hit -"i^-trti Hic 3, t rt X 't' Tricyclic terpenes are represented by cyclene ^rtj or tricyclene \ ,4 C Laboratory Preparations 1, Camphor a, Bornyl chloride b, Camphane c, Isobornylacetate d» Isoborneol e. Camphor 2. Thymol a. Paracymene b. Paranitrocymene c. Carvacrylamine d. Paracymene diazonium chloride e. Thymol Method for Preparation of Camphor aH3 \ c e. I cw3C-<mi Crix H.<^ C H H 1 nt Tse. I c xC I C.-^"A oC-fcH, CH3 HiO Hi<l _L^"- C c. H CH3 ^^3 C ^ c_ ^ HxC' I ^CHoH Coic. jx ^ h~^-^ """^ H.e^ \ c Bornyl Chloride a, chemicals: pinene 200 grams concentrated HCl concentrated H^SC^ ethyl alcohol 50 grams h. procedxire: Dry hydrochloric acid gas Is generated by dropping concentrated sulfuric acid into a flask containing concentrated hydrochloric acid. The gas is le«d through an empty gas bottle into two large containers of concentrated sulfi-ric acid, to insure perfect drying, and thence through an empty bottle into the pinene, which is embedded in an ice salt mixture and kept at 12?,After a steady stream of gas is lead into the mixture for tv/o hours, the pinene ceases to absorb the hydrochloric acid. The pinene is allowed to stand overnight, packed in ice. The next day it is repacked for two hours, the temperature lowered to -10*?, White crystals form. The crystals are filtered with suction. The filtrate, on cooling, yields more crystals. This bornyl chloride is dissolved in hot ethyl alcohol; the solution is filtered to free it from impurities, and the filtrafce is cooled to -5t. The crystals reform. The yield is 110 grams. c, properties: Bornyl chloride is a snow;;^ white crystalline pov/der with a distinct odor of camphor. Its melting point is 148^, It is very volatile; it dissolves in alcohol and ether. Camphene a, chemicals: ortho cresol 200 grams potassium hydroxide 75 grams bornyl chloride 100 grams anhydrous calcium chloride b. procedure: Into a 500 cc. roundbottom flask is placed 200 grams of melted ortho cresol, and 75 grams of crushed potassium hydroxide are added. The mixture is warmed, and then the water is distilled off, using a water cooled condenser. At 150% this condenser is exchanged for an air condenser. The mixttxre is heated to 180%, The flask is cooled, and 100 grams of bornyl chloride are added in three portions, with vigorous shaking of the mixture. Then a very long air condenser is attached upright, and the mixture refluxed for three hours. The camphene is then distilled, the portion boiling from 150c.-160% is collected and shaken with dilute sodium hydroxide, and then cooled in an ice salt mixture. The camphene solidifies into crystalline Iximps, The camphene is filtered and washed with ice water. It is then melted and the vrater contained in 5.t is decanted from it. The camphene is remelted, this time with a bit ofi anhydrous calcium chloride added. Again it is decanted, and then fractionally distilled. The portion boiling between 155^-160H.is cellected. This is tested for chlorine by dipping a copper wire into it, and then placing the v/ire into the flame, A green chlorine color appears in the flame. The camphene is redistilled. This time it is chlorine free. The yield is 49 grams. c, properties: Camphene is a colorless, crystalline mass which melts at 52% and boils at 160cf. It is insoluble in water, but dissolves readily in alcohol and ether. Isobornylacetate' a. chemicals: camphene 48 grams glacial acetic acid 125 grams concentrated H^^se^ powdered sodium carbonate crystals 300 grams b, procedure: To a solution of 48 grams of camphene in 125 cc. of glacial acetic acid contained in a flask, is added a mixture of 2cc. of concentrated HASO^ and 3cc. of water. This is warmed on a steam bath at 50d.-60%..for two sind one half hours with frequent shaking. Two layers, which form at first, disappear after heating. The reddish solution of ester is placed in a large beaker, 100 cc, of water is added,and then it is neutralized with 300 grams of powdered sodium carbonate crystald. The ester is separated and dried with anhydrous calcixm chloride. The isobornylacetate is then fractioned in vacuo. The portion boiling at 95c-105 c.is collected, A pressure of 12 millimeters is obtained for the distilling by means of a vacuum pump, and measured with a manometer. The yield is 35 grams, c. properties: Isobornylacetate ia a colorless liquid that smslls like valerian. It boils at 102tat 12 millimeters pressure. Isoborneol a, chemicals: isobornylacetate 30 grams ethyl acetate 60 grams potassium hydroxide 12 grams b. procedure: In a 250 cc, flask 30 grams of isobornylacetate are dissolved in a solution of 60cc, of ethyl alcohol and 12 grams of potassium hydroxide, and heated to boiling for three hours under a reflux condenser on the steam bath. The solution is then poured into cold water, and the isoborneol separates as a light yellow semi-solid mass. The beaker is placed into ice and stirred mechanically for two hours. The isoborneol becomes solid. The crystals are filtered with suction, and washed with cold water; then pressed dry. xhe yield is 23 grams. c. properties: Isoborneol is a white crystalline solid, which is very volatile. Its melting point is 212c°, Camphor a, chemicals: concentrated HNOa 40 grains red fuming HNO^ (s.g. 1.6) 12 grams isoborneol 20 grams sodium hydroxide 3 grams potassium permanganate 5 grams h, procedure: A mixture of 40 grams of concentrated nitric acid (s, g, 142) and 12 grams of red fuming nitric acid (s.g,1,6) is made in a 200 cc. flask and cooled to 20"-25t, In small amounts, 20 grams of isoborneol are added cautiously, keeping the temperature at 20''-252, A compound of camphor and nitrogen pentoxlde separates as an oily, slightly colored mass. The mixture is stirred for 30 miniites, and then poured upon cracked ice. The camphor separates out into white lumps. It is filtered with suction and washed with ice water. It is purified by mixing it withia dilute solixtion of 3 grams of sodium hydroxide and 5 grams of potassium permanganate, and then distilled with steam through an air cooled condenser into a wide mouthed bottle, which is cooled in cold running water.