Lecture 3 (1) PDF

Chemistry of volatile oils constituents Types of constituents detected in volatile oils V. O. are complex mixtures formed of: 1. Terpenoids (mainly mono- & sesquiterpenoids) 2. Aliphatic compounds (acyclic, straight chain compounds which may be terpenoids). 3. Phen...

Chemistry of volatile oils constituents Types of constituents detected in volatile oils V. O. are complex mixtures formed of: 1. Terpenoids (mainly mono- & sesquiterpenoids) 2. Aliphatic compounds (acyclic, straight chain compounds which may be terpenoids). 3. Phenyl propanoids (C6-C3, aromatic) 4. Miscellaneous compounds e.g. organo-nitrogen & organo-sulfur compounds.  Each group includes non-oxygenated (hydrocarbons) & oxygenated compounds.  Oxygenated constituents are generally responsible for the characteristic odor of the oil. 1  Removal of terpenoid hydrocarbons  Oils rich in terpenoid hydrocarbons deteriorate rapidly on storage due to oxidation & polymerization → bad smelling (with turpentine-like odor) & resinified products.  Removal of most terpenoid hydrocarbons → Fractional distillation “Terpeneless oils" by any of the following methods: 1. Fractional distillation under reduced pressure: hydrocarbons have lower b.p. than oxygenated compounds, they distill first & are rejected. 2. Column chromatography on silica gel: hydrocarbons are eluted with n-hexane then oxygenated compounds with absolute alcohol. 3. Selective extraction of oxygenated components with dilute alcohol followed by distillation. Column chromatography 2  “Terpeneless oils” “Volatile oil isolates”  Oils from which most An isolate is a single chemical terpene hydrocarbons are substance isolated from the oil removed: (may be oxygenated or non- oxygenated) 1. More stable being less liable to deterioration “Oleoptene & Stearoptene” 2. Richer in oxygenated compounds. Stearoptene = solid fraction separating on cooling a v.o. 3. More soluble in low-strength (previously known as alcohols camphors), consists of 1 or more solid oxygenated 4. Used in smaller amounts to compounds give the same strength of odor. Oleoptene = remaining liquid 5. More expensive than natural fraction, mainly formed of oils hydrocarbons 3  Isolation of volatile oil constituents  Physical methods (cooling, fractional distillation, fractional crystallization & preparative gas chromatography)  Chemical methods depend on: 1. Solubility differences in acids or alkalis 2. Derivatization (due to presence of functional groups). 3. Adduct formation (specific for certain compounds). N.B.: The original compound can be regenerated by decomposition of the derivative or adduct. 4  Chemical methods for isolation of V.O. constituents Solubility in alkalis: 1. Compounds containing -COOH group (strongly acidic) + mild alkali (Na2CO3) → water soluble Na salts (decomposed by acids). 2. Phenolic compounds (mild acids) + aqueous NaOH or KOH (strong alkalis) → water soluble Na or K phenates (decomposed by acids) → phenol. Cassia flask Derivatization: 1. Alcohols → esterification → phenyl urethans or acid phthalates 2. Carbonyl compounds → derivatives e.g. crystalline bisulfites, semicarbazones, phenyl hydrazones & oximes. 5  Chemical methods for isolation of V.O. constituents (cont.) Formation of crystalline additive products (Adduct formation): 1. Geraniol, benzyl & cinnamyl alcohols + anhydrous CaCl2. 2. Carvone + H2S gas in presence of NH3. 3. Cineole + strong acids (e.g. H3PO4) & resorcinol 4. Unsaturated terpene hydrocarbons + HCl, HBr & NOCl (nitrosyl chloride or Tilden’s reagent). 5. Azulenes +  Strong mineral acids e.g. H3PO4 and H2SO4  Ferrocyannic acid  Nitrocompounds e.g. picric, styphnic & tortylic acids. 6  Biosynthesis IPP is formed from acetyl-CoA via the mevalonate pathway (the "upstream" part), and then is isomerized to dimethylallyl pyrophosphate by the enzyme isopentenyl pyrophosphate isomerase.  Terpenoids (Terpenes)  They constitute the largest known group of secondary metabolites.  They yield isoprene as final product of destructive distillation (= pyrolysis).  The term “terpenes” should better be used to indicate the unsaturated hydrocarbons  Isoprene(C5H8), a 5 carbon-atom unit, is considered as the building unit of all terpenoids h h 1 CH 2 t t 4 Abbreviated structure H2C 3 C 2 h=head, t=tail C CH3 Isoprene, 2-methyl 1:3 butadiene, 1,3 isopentene 7  Isoprene rule for formation of terpenoids  Theoretical biogenetic rule which states that: “Each group of terpenes originates from the head-to-tail condensation of a variable number of isoprene units”. Isoprene h t Bicyclic Isoprene Acyclic Monocyclic Monoterpene monoterpene monoterpene Isoprene h t Isoprene t h Isoprene Acyclic Monocyclic sesquiterpene sesquiterpene Coupling of isoprene units to yield mono- & sesquiterpenoids 8  Types of terpenoids Class Emperical Isoprene examples formula units Hemiterpenoids C5H8 1 Isoprene Monoterpenoids C10H16 2 Limonene Sesquiterpenoids C15H24 3 Santalene Diterpenoids C20H32 4 Abietic acid Triterpenoid C30H48 6 Saponins Tetraterpenoid C40H60-64 8 Carotenoids Polyterpenoid (C5H8)n ∞ Rubber  Terpenoids in Essential Oils  Thousands of terpenoids are identified in essential oils  Mainly mono- or sesquiterpenoids (volatile & of low M. Wt.)  Acyclic (i.e. aliphatic) or alicyclic (i.e. with non-aromatic ring structures)  Hydrocarbons or oxygenated (alcohols, aldehydes, ketones, esters, ethers, oxides or peroxides)  Often optically active occurring as d-, l- & dl isomers  Monoterpenoids (10 C) 1. Most abundant class of the essential oil constituents. 2. Consist of 2 molecules of isoprene (C 5H8) 3. Hydrocarbons have the empirical formula C10H16 4. Acyclic or alicyclic (mainly mono- & bicyclic) 10  Nomenclature of terpenoids  Chemical names are derived from the corresponding saturated hydrocarbon skeleton 6 5 7 1. The acyclic monoterpenoids are 4 8 2, 6-dimethyl octane (myrcane) derivatives. 3 2 1 2. Most monocyclic monoterpenoids are para- Myrcane menthane rarely meta-menthane derivatives. 7 3. Bicyclic monoterpenoids are thujane, carane, 6 1 2 pinane, camphane or fenchane derivatives. 3 3 5 4 4. Acyclic sesquiterpenoids are trimethyldodecane derivatives. 9 8 10 p-Menthane m-Menthane 5. Mono- & polycyclic sesquiterpenoids are bisabolane, humulane, elemane, germacrane cadinane, santalane, cedrane derivatives etc… 7 1 6. The number & position of the double bonds are 6 2 indicated e.g. a double bond between C1 & C2 by 5 8 3 1 ; while a double bond between C1 & C6 by 1(6) 4  Pinane Trivial names are better adopted for facility. 12  Saturated hydrocarbon skeletons of mono- & sesquiterpenoids Monoterpenoids 7 6 1 5 7 6 2 4 8 3 5 Sesquiterpenoids 3 4 2 6 7 8 5' 6 5 9 1 8 ' 6' 4' 5 9 10 4 ' Myrcane 3 12 4 3 m-Menthane 10 1' 3 p-Menthane 11 2' 2 2 1 1 7 Bisabolane Elemane Trimethyldodecane 1 6 2 8 5 3 4 Thujane Carane Pinane Germacrane Humulane Cadinane Bornane (Camphane) Fenchane iso-Camphane 13  Isomerism of Monoterpenoids  Structural isomerism due to shift in the double bonds Example: myrcene & ocimene ; limonene & a-terpinene Myrcene Ocimene Limonene a−Terpinene  Structural isomerism due to shift in the position of a substituent group Example: p-Menthadiene (e.g. limonene) & m-menthadiene (e.g. sylvestrene) derivatives. Limonene Sylvestrene 14  Isomerism of Monoterpenoids  Geometrical isomerism: e.g. the cis-trans isomeric alcohols, nerol & geraniol. CH2OH H H CH2OH Geraniol (trans) Nerol (cis)  Optical isomerism: due to the presence of one or more asymmetric C atoms e.g. dipentene occurs in d-, l - & dl - forms due to asymmetry at C4 (not involved in a double bond), while terpinene is optically inactive.  Strainless ring isomerism: more stable chair & boat configurations than planar.  Isomerism due to molecular rearrangement of the ring structures: e.g. from pinane to camphane etc…. Pinane Camphane 15  Phenyl propanoids (C6-C3) or Aromatic constituents  Less common than the terpenoids.  Contain a C6 phenyl ring to which is attached a C3 propane side chain  Many are phenols (e.g. eugenol), or phenol ethers (e.g., anethole, safrole, apiole), & aldehydes e.g., cinnamaldehyde.  The propane side chain may be formed of 2 or 1 C (C6-C1) e.g. vanillin, methyl salicylate & methyl anthranilate.  Certain aromatic C10 compounds e.g. p-cymene, thymol & carvacrol can be described under monoterpenoids. 16  Examples of phenyl propanoids in volatile oils OH OH p-Cymene Thymol Carvacrol OCH3 OH O O OCH3 O H3CO O OCH3 Anethole Eugenol Saffrole Apiole OH OCH3 O CHO OCH3 CH2OH CHO OH 17 Vanillin Cinnamaldehyde Methyl salycilate Phenyl ethyl alcohol  Hydrocarbons in Volatile oils 18  Different Types of Hydrocarbons Acyclic or aliphatic ACYCLIC TERPENOID HYDROCARBONS 1. Monoterpenoids: MONOTERPENOIDS SESQUITERPENOIDS myrcene & Ocimene 2. Sesquiterpenoids: Farnesene Sesquicitronellene  Myrcene Ocimene Farnesene Sesquicitronellene Alicyclic 1. Monoterpenoids: Monocyclic: limonene Bicyclic : a-pinene 2. Sesquiterpenoids AROMATIC HYDROCARBONS Monocyclic: zingiberene Bicyclic : cadinene Tricyclic : santalene  Aromatic e.g. p-cymene & azulenes p-Cymene Chamazulene Guaiazulene 19  Alicyclic Terpenoid Hydrocarbons MONOTERPENOIDS Monocyclic Bicyclic Para-menthadienes Alicyclic 1. Monoterpenoids: (+)Sabinene 3Carene Monocyclic: limonene Limonene a-Terpinene Bicyclic : a-pinene & Dipentene 2. Sesquiterpenoids Meta- menthadienes Monocyclic: zingiberene Bicyclic : cadinene (+)a-Pinene (+)-Pinene Tricyclic : santalene Sylvestrene a Sylvestrene b (+) Camphene __________________________________________________________________________________ SESQUITERPENOIDS Monocyclic Bicyclic Tricyclic H H 20 Zingiberene -Cadinene a-Santalene  Acyclic Monoterpenoid Hydrocarbons Myrcene & Ocimene 10 Source  Myrcene: 6 5 7 5 7 Occurs in oils of hops (Humulus lupulus, 4 8 Cannabinaceae), bay ‫( القرنفل الكاذب‬Myrcia acris, 3 3 Myrtaceae) lemongrass ‫( حشيشة الليمون‬or citronella, 9 2 1 1 Cympobogon nardus , Gramineae ) & turpentine. Myrcene Ocimene  Ocimene: Occurs in oils of Basil ‫( ريحان‬Ocimum basilicum & Ocimum gratissimum Lamiaceae). Basil Lemon grass Hops Bay 21  Acyclic Monoterpenoid Hydrocarbons - Myrcene & Ocimene Properties 10 Liquids (b.p. 2ry > 3ry alcohols → esters  Most common esters are the borates, acid phthalates & urethans (or carbamates). 1. Boric acid esters (borates) 1ry & 2ry alcohols react easily → borates, while 3ry alcohols do not react. The reaction is used mainly to separate 1ry & 2ry from 3ry alcohols. 2. Benzoates X Only 1ry & 2ry alcohols react → benzoates 47  Alcohols in volatile oils - Reactions 3.Phthalic acid esters (Phthalates) 1ry alcohols react under less drastic conditions than 2ry alcohols, 3ry alcohols do not react O O O Alcoholic O Heat OR Na HCO3 ROH + O OR KOH OK ONa ROH OH ONa + Alcohol O O Saponification O O Phthalic Acid phthalate Sodium phthalate Sodium Alcohol anhydride monoester monoester Potassium phthalate 48  Acyclic Monoterpenoid Alcohols - Citronellol Source d-form: oil of citronella. 6 * 8 l-form (-rhodinol or levocitrol): in oil of geranium CH2OH CH2OH & oil of rose 2 Properties a−Citronellol -Citronellol Terpinolene form Limonene form 1. Optically active liquid 2. With rose-like odor 3. Stable, its stability is due to the presence of only one double bond in the molecule (c.f. geraniol & nerol, 2 double bonds). Uses In perfume, cosmetic & soap industries to impart a rose-like odor. As substitute for rose oil. Insect repellent. 50  Acyclic Monoterpenoid Alcohols – Geraniol & Nerol Source H CH2OH H Geraniol & its esters: Oils of Palmerosa (95 %), CH2OH geranium (40 - 50 %), citronella (30 - 40 %) & rose Nerol & its esters: Oils of neroli, petit grain, Nerol Geraniol bergamot (cis isomer) (trans isomer) E-isomer Z-isomer Isolation Geraniol : by formation of the crystalline calcium chloride derivative Nerol: difficult to be isolated in a pure form. → 5  Acyclic Monoterpenoid Alcohols – Geraniol & Nerol Separation of geraniol from nerol & other alcohols Geraniol is usually present in oils together with nerol & citronellol, it can be separated by formation of : 1.Calcium chloride additive compound & regeneration by warming with water. Anhydrous CaCl 2 2 Geraniol (Geraniol)2. CaCl2 Warm water 2. Acid phthalate silver salts followed by fractional crystallization: XX O O O ROH Heat Ag + + O OR OR OH OAg Alcohol O O O Phtalic Acid phtalate Acid phtalate anhydride monoester silver salt 52  Acyclic Monoterpenoid Alcohols – Geraniol & Nerol Properties Nerol & geraniol: 1. Colorless, optically inactive (c.f. citronellol & linalol) liquids with rose-like odor (similar to citronellol). Geraniol: 1. Form a complex with anhydrous CaCl2 2. + NaHSO3 → stable bisulfite complex not decomposed by NaOH (c.f. bisulfite complexes of carbonyl compounds which are decomposed by both acids & alkalis). XX Nerol: Does not form a complex with anhydrous CaCl2 (c.f. geraniol) 53  Acyclic Monoterpenoid Alcohols – Geraniol & Nerol Uses 1. Geraniol & its esters are extensively used in perfume, cosmetic & soap industries for compounding rose scents. 2. As substitute for rose oil. 3. Geraniol is also used as a natural insect-repellent 54  Acyclic Monoterpenoid Alcohols – Linalol (Linalool) Source HO *  Common component of essential oils.  Occurs either free (in d- & l- isomers) or in the form of esters, especially the acetate. Orange flower (+) Linalol 1. d-form: oils of coriander, nutmeg & sweet orange 2. l-form: oils of lavender, neroli, bergamot, lemon & salvia 3. Linalyl acetate: oils of lavender & bergamot Salvia officinalis Lavender Isolation By fractional distillation of the saponified oil Coriander fruit 55 30/10/2011  Acyclic Monoterpenoid Alcohols – Linalol (Linalool) Properties  Optically active liquid with lavender-like odor.  The rapid degradation of linalol is due to the presence of 2  double bonds & a 3ry alcoholic group. XX Uses HO * (+) Linalol ♣ Linalol & its acetate ester are widely used in perfume, cosmetics, soap & flavor industries to impart a lavender-like odor. ♣ As a substitute for lavender oil ♣ Antirheumatic. 56  Monocyclic monoterpenoid alcohols - Menthol * Source 1 *  Most common isomer is l-menthol. 4 * 3 OH  It is present in oil of peppermint (Mentha Menthol piperita, Labiatae or Lamiaceae) 50 - 65 %, & in Japanese mint oil (Mentha arvensis) up to 75 -90 %. Structure Menthol has 3 centers of asymmetry, it is Mentha arvensis optically active and exists as 8 optically active isomers (23 = 8). Mentha piperita 57  Monocyclic monoterpenoid alcohols - Menthol Isolation From Japanese mint oil (75 - 90 %) by gradual cooling 1. Cool to 15 oC centrifuge and collect the deposited crystals (1st crop). 2. Cool at 5 oC then -10 oC , collect the deposits after centrifugation (2nd & 3rd crops). 3. Remaining oil contains about 40-50% menthol + large amount of menthone. 4. Menthone is removed by formation of its oxime, add ether & shake with dilute H2SO4 (menthone in the aqueous layer) 5. Cool the ketone-free oil → residual menthol. Semis-ynthesis XX Semi-synthetic dl-menthol is obtained or + H2 by catalytic reduction of thymol OH O Cu chromite OH or 58 pulegone Thymol Pulegone Menthol  Menthol - Isolation Peppermint oil cooling at 15 oC, centrifuge Menthol-crystals Liquid oil cooling at 5 oC, centrifuge Menthol-crystals Liquid oil cooling at -10 oC, centrifuge Menthol-crystals Liquid oil (Menthone + Menthol) NH2OH.HCl Oxime + Menthol ether dil.H2SO4 ethereal layer aqueous layer (Menthol) (Oxime) 59  Monocyclic monoterpenoid alcohols - Menthol Properties  Needle crystals.  Powerful peppermint-like odor & a cooling taste. Tests for identification Drop of water Crystals in conc H2SO4 + 1drop Vanillin/H2SO4 → orange-yellow color + few drops of H2O → violet color. Pharmacological action & uses  Local action: antipruritic (antiitching), counter irritant, mild local anesthetic & antiseptic.  Systemic action: heart depressant , carminative & gastric sedative.  Flavoring agent in mouthwashes & toothpastes, in candies, chewing gums & cigarettes. 60  Monocyclic monoterpenoid alcohols - a-Terpineol 1 Source 2 a-Terpineol is present in free & ester forms. * OH  d-form : oils of neroli & petit grain 8  l-form occurs: camphor tree oil a- Terpineol  dl-form : oil of cajuput (Melaleuca spp., Myrtaceae) Camphor tree Isolation  Fractional distillation Semisynthesis XX Melaleuca leucadendron On industrial scale, terpineol is Obtained from pine oils rich in OH Dipentene & a-pinene by treatment or 60% H2SO4 With 60 % H2SO4. OH OH Limonene a−pinene Terpin hydrate a−Terpineol 61 or Dipentene  Monocyclic monoterpenoid alcohols - a-Terpineol Properties  Terpineol, when pure is a crystalline solid.  Its solution is optically active  It has a characteristic lilac odor (pleasant odor).  Effect of acids & acidic reagents: ▪ According to reaction conditions, terpineol is converted to different monoterpenoids. ▪ Terpeniol is considered as a key substance in semisynthesis of several hydrocarbons & certain oxygenated monoterpenoids. Dipentene + KHSO4 +Acetic anhydride + heat + 40 % H2SO4 Terpin hydrate Terpineol + HCOOH Terpinolene + H3PO4 Terpinolene + Terpinene + Cineole Uses Terpineol & terpinyl acetate are important ingredients in perfume, cosmetic & soap industries. 62  Bicyclic monoterpenoid alcohols - Borneol & isoborneol Source Borneol occurs as d- or l- isomer, free or as * * OH * * H ester mainly the acetate. H OH ▪ d-Borneol (or Borneo camphor): oils of Dryobalanops camphora & D. oblongifolia Borneol Isoborneol ▪ l- Borneol: oils of citronella, coriander, valarian root & Pinus pallustris. ▪ dl Borneol: Valerian root oil ▪ Bornyl acetate is the main constituent of pine needle oils (up to 40 %). Isolation  Distilled pine needle oil is saponified (hydrolysis Dryobalanops of esters) → fractional distillation (removal of camphora hydrocarbons). Pinus pallustris  Fraction boiling between 205 - 215 o C cooled → crystals of borneol.  Remaining borneol isolated as acid phthalate. Valarian root 63 Valarian  Bicyclic monoterpenoid alcohols - Borneol & isoborneol Semi-synthesis HCl gas Cl Isomerization Cl OH KOH  From a -pinene: -10oC Molecular Rearangement a-Pinene Pinene Bornyl Borneol  From camphor: hydrochloride chloride By reduction in presence of catalyst Purification Borneol usually occurs in combination with isoborneol & camphor. Separation from camphor  Method 1: Borneol + phthalic or succinic anhydride + heat → borneol esters [acid phthalate or acid succinate] + aqueous NaOH → Na salts soluble in water. Camphor extracted with organic solvents.  Method 2: Camphor removed by formation of its oxime which is separated by shaking with dilute H2SO4 (oxime dissolve in dil H2SO4) Separation from isoborneol XX Based on that isoborneol is more easily H dehydrated than borneol → camphene OH Zn Cl2 / Benzene hydrocarbon → fractional distillation to Isoborneol Heat 64 remove camphene. Camphene  Bicyclic monoterpenoid alcohols - Borneol & isoborneol Properties Borneol: 1. 2ry alcohol , Crystalline solid with camphor-like (camphoraceous) odor. 2. Easily oxidized to camphor by: ► Distillation over CuO ► Treatment with Cl2. ► Borneol is stable to dehydrating agents (c.f. isoborneol). Isoborneol: 1. 2ry alcohol [O] 2. Unstable to dehydrating agents. d-isoborneol l-camphor [O] 3. When exposed to atmospheric oxygen in l-isoborneol d-camphor presence of catalyst, HNO3 or KMnO4 is oxidised to camphor with change in optical rotation i.e.: Uses  Borneol is used for scenting all kind of technical preparations such as room sprays, inhalants & soaps  Some of its esters e.g. borneol acetate are used in pharmaceutical preparations. Derivatives of pharmaceutical importance  d-Bornyl isovalerate: sedative.  d-Bornyl a- bromoisovalerate: sedative & hypnotic.  Bornyl chloride: antiseptic.  Bornyl salicylate: counter irritant. 65  Tricyclic sesquiterpenoid alcohols - a-Santalol Source Main constituent of East-Indian sandal wood oil CH2OH Isolation a−Santalol Sandal wood oil is first treated with KOH (to remove phenolic constituents), then fractional distillation → a-santalol Properties  Tricyclic sesquiterpenoid 1ry alcohol  Viscid liquid, yellow in color with odor of sandalwood. Uses Medicinal & odoriferous values of sandalwood are due to santalol content of the volatile oil. 66  Aromatic alcohols Aromatic alcohols common in volatile oils are benzyl, phenyl ethyl & cinnamyl alcohols. CH2OH CH2CH2OH CH=CHCH 2OH Benzyl alcohol Benzyl alcohol Phenyl ethyl alcohol Cinnamyl alcohol Source Benzyl alcohol occurs mainly in the form of its esters.  Benzyl benzoate & benzyl cinnamate: balsam Peru, balsam Tolu & storax Jasmine  Benzyl acetate: oils of jasmine, tuberose & gardenia. Isolation Tuberose 1. By fractional distillation of the saponified oils. 2. By formation of a complex with anhydrous CaCl2 in ether & regeneration by treatment with warm water. 67 Gardenia  Aromatic alcohols- Benzyl alcohol Properties ▪ Clear colorless liquid with a faint aromatic odor. ▪ Slightly volatile with seam ▪ On bad storage (exposure to air & light) → bitter almond odor (benzaldehyde) → crystalline deposit (benzoic acid). CH2OH CHO COOH [O] [O] Benzaldehyde Benzoic acid Benzyl alcohol Liquid with bitter almond odour crystalline solid Liquid Identification  Formation of derivatives e.g. acid phthalate (m.p.106-107 oC) or of a double compound with CaCl2  Oxidation with chromic acid / H2SO4 or KMnO4 → Benzoic acid Uses  Benzyl alcohol, mainly as its aliphatic esters, is widely used in perfume & cosmetic industries to give synthetic flowers odor e.g. jasmine, gardenia, & tuberose.  As diluent & fixative (due to its low volatility) in perfume mixtures.  As antimicrobial pharmaceutical aid (similar to phenols). 68  Aromatic alcohols- Phenyl ethyl alcohol Source CH2CH2OH Oils of rose, neroli, geranium & hyacinth Properties & Uses Liquid with a rose-like odor. Antimicrobial pharmaceutical aid, preservative In flavor & perfume industries, especially those of rose-scented perfumes. Rose 69 Hyacinth Insect repellent: citronellol, geraniol, nerol, citronellal, citral a & b Insect attractant: terpineol , eugenol Antirheumatic: chamazulene, linalool Perfume fixative: benzyl alcohol Antipruritic : Menthol, camphor counter-irritant : fenchone Mixtures: borneol, camphor by ester of borneol, oxime of camphor geraniol, nerol: by CaCl2 (Isolation) by urethane esters (identification) Bad storage: limonene, benzyl alcohol, anethole Complex with CaCl2 : geraniol, benzyl alcohol 70