Decomposition of linalool by cosmetic pigments

j. Soc.Cosmet. Chem.,38, 385-396 (November/December 1987) Decomposition of linaloolby cosmeticpigments H. FUKUI, R. NAMBA, M. TANAKA, M. NAKANO, ...
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j. Soc.Cosmet. Chem.,38, 385-396 (November/December 1987)

Decomposition of linaloolby cosmeticpigments H. FUKUI,

R. NAMBA,

M. TANAKA,

M. NAKANO,

and

S. FUKUSHIMA, Shiseido Laboratories, I050, Nippa-cho,Kohoku-ku, Yokohama-shi, Japan223.

Received July 6, I987. Presented at theCatalysis Meeting,Sapporo, Japan, October, 1983. Synopsis

The reactionbetweenpigmentsand linaIool,which is a commoncomponentof perfumes,wascarriedout with a microcatalytic reactorat 178øC.Mostof the linaloolwasdecomposed by thesepigmentswith high catalyticactivity, and the decomposition productsdiffereddependingon the natureof the pigment. The decomposition productswereidentifiedby massspectroscopy and infraredspectroscopy showingthat these productsweredehydratedlinaloolsuchasmyrcene,ocimene,and alloocimene,and cyclizedproductssuch as limonene,terpinolene,and alpha-terpinene.Furthermore,p-cymenewasproducedby thosepigments having a high catalytic activity. The followingdecomposition mechanismis suggested for linaloolfrom the decomposition products:Dehydratedlinalool is formedvia a carboniumion intermediateformedon acidicsiteson the pigments,and cyclizedproductsare formedafter allyl rearrangement. Finally, p-cymene,which is a main causeof unpleasantodorin somepigmentedcosmetics,is formedby dehydrogenation of the cyclizedproducts.

INTRODUCTION

If metal oxidesand clayshavingcatalyticactivity are usedas pigmentsfor cosmetics, other components in the products,for example,perfumes,oils, and medicamentsmay be decomposed. In the caseof perfumes,the isomerizationof 2-pineneoversolidacids (1) andthe reactionof d-limoneneoxideoversolidacidsor bases(2) havebeenreported by Tanabe.Dehydrogenation of d-limoneneto p-cymenein the presence of sodiumwas studiedby Pinesand coworkers(3). Investigationsof suchreactionshavebeenundertaken to clarify the catalyticactionrelatedto perfumesynthesis,while deteriorationof the perfume in cosmetics,whereinperfumesand pigmentsexist together, have been scarcelystudied.Holznerinvestigatedthe degradationof linalooland linalyl acetateby kaolinireand talc. However,he did not describedecomposition products(4). Previouslywe reportedthe dehydrationand dehydrogenation of isopropylalcoholand isomerizationand polymerizationof propyleneoxideoverpigmentsusinga microcatalytic reactor(5-8). The microcatalyticreactoris the most suitablemethod for measuringthe decomposition of perfumesoverpigmentssinceit permitsrapidquantitative evaluationof the decomposition reaction.Furthermore,this analyticalmethodhasbeen established by Basserr etal. (9). We selectedlinaloolasthe perfumeto studybecause it 385

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JOURNAL OF THE SOCIETYOF COSMETICCHEMISTS

is presentin bergamotand lavenderoil at high levelsand it is indispensable to many other fragrances.

MATERIALS

AND

METHODS

MATERIALS

The pigmentsemployedin theseexperiments are describedin Table I. Most are raw materialsfor cosmetics.Linaloolwasof high purity from BBA Co. Ltd., and t-butyl alcoholwasa guaranteedreagentfrom Wako Pure ChemicalIndustriesLtd. Both alcoholsindicatedone peak via gas chromatography. Authentic samplesof terpenoids were kindly suppliedfrom TakasagoCorp. METHODS

Decomposition of terpenoids bypigments. The reactionwascarriedout by a microcatalytic reactor(HonmaRiken Co. Ltd.) at 178øC.A pigment(10 mg) washeldwith small plugsof quartzwoolin a quartzreactortubewith an insidediameterof 4 mm. Linalool wasinjectedinto a nitrogengasstreamat a flow rate of 50 ml/min usinga microsyringe. When the linalool passedthroughthe pigment bed, decomposition of linalool occurred.The productsweresweptout of the reactortubeby the carriergasandtrapped into the tubeof tenaxGC 400 mg. The trappedproductsweredesorbed at 200øCand Table

I

CosmeticPigmentsUsed in This Study

Specific surface area

Pigments

Remarks

Titanium

dioxide A

anatase

Titanium

dioxide R

Titanium

dioxide A-R

Black iron oxide

rutile anatase-rutile -silicondioxide goethite hematite magnetite

Cobalt blue

cobalt aluminium

Zinc oxide Silica Yellow

iron oxide

Red iron oxide

Hydrated chromium oxide

(m2/g) 11.4

14.9 54.0 4.0 200.4 19.4 15.4 5.7

Manufacturer #328, National Lead

R-KB- 1, Bayer p-25, Degussa SakaiKagakuKogyoLtd. Aerosil200, Degussa Amaochre# 1, AmagasakiSeiteisho Ltd. Mapicored-516L,Titan KogyoLtd. MapicoblackBL-100, Titan Kogyo Ltd.

18.5

Cobalt blue-LMC,

80.0

Mitubishi Metal Corp. Ultragreen3597

ferric ammonium

30.3

671 Milori blue,

ferrocyanide -muscovite --

11.3 7.7 11.8

DainitiseikaLtd. Talc-15, AsadaMilling Co. Ltd. Mica #800, Wakita KogyoLtd. GeorgiaKaolin

oxide --

Whittaker Prussian blue Talc Mica

Kaolinire

Ultramarine

blue

--

9.1

Ultramarine

violet

--

11.3

Clark & Daniels INC

Daiichi blue C-B80

Daiichi Kasei Kogyo Ltd. Daiichi rose

Daiichi KaseiKogyo Ltd.

DECOMPOSITION

OF LINALOOL

BY PIGMENTS

387

transferredinto a gas chromatograph (ShimadzuGC 7A) equippedwith a hydrogen flame detector,and a 3-m columnof 5% FFAP on Chromosorb W80/100 at 80øCfor

fourminutes,at a heatingrateof 5øC/minup to 220øC.Linaloolrecovery wasobtained from a calibrationcurveof linalool,and the proportionof decomposition productswas calculatedfrom the peakareason the chromatogram.

Decomposition of terpinoleneand limonenewasconducted underthe sameconditions as for linalool.

Identification of thedecomposition products fromlinalool.The decomposition productswere trappedinto a teflontube at liquid nitrogentemperatureand after addingn-hexane, introducedinto a GC/MS andGC/IR by usinga microsyringe at roomtemperatureand identifiedby massspectroscopy (Hitachi RMU-6M) and infraredabsorption spectroscopy(BioladFTS-15C) (10). For GC/MS and GC/IR, the 5710 GC (Hewlett Packard)wasusedwith a column of 3m x 2 mm (5% FFAP/Chromosorb W 80/100), which is the sameas that of the micro-

catalytic reactor. TheMSwassetat 20 eV of ionization potential, 200øCof ionsource temperature, and3000V of accelerating voltage.Dataprocessing wasconducted by the HITAC-1011 minicomputer(Hitachi) for continuouslymeasuringspectraevery 5 seconds.

ForIR, a FTS-15C(Biolad)connected with a GC/IR opticalsystemwasused.The light

pipeof GC/IR with 2.5 mm insidediameter and60 cmlong(insidecoated withgold) wasmaintainedat 200øC.Data processing wasconducted by a NOVA-3 minicomputer (Data General, High Comp. 32-type arrayprocessor).

Decomposition of t-butylalcohol bypigments. The decomposition of t-butylalcohol was conducted in thesamewayasfor linaloolby usingthemicrocatalytic reactor.Helium wasusedasa carriergasat a flowrateof 26 ml/minwith 0.2 g of thepigment,while3 •xl of t-butylalcohol wasinjected.Foranalysis, asfor linalool,a gaschromatograph (Shimadzu GC-4BPTF) andTCD detector wereusedwiththecolumnof 3 m Polapack R (80/100)heated at 80-180øC,raising thetemperature at a rateof 8øC/min.Under theseconditions,the analysis of t-butyl alcohol,isobutene, and waterwasaccomplished.

Analysisof thedehydration reaction. Sincethe dehydrationof linaloolis a unimolecular reactionin a gasphase,the reactionrate is first-orderwith respectto the concentration of linalool. Basserradvocates that in the reactionundernonsteady-state conditionslike this, the first-orderreactioncanbe analyzedby the followingequation(9): ln[l•-x)]

= kK (273R) W/F ø

wherex is thedegreeof conversion, Fø is theflowrateof carriergasat 0øC,W is the total weight of the catalyst,R is the gas constant,K is the adsorptionequilibrium constant, and k is the first-order rate constantof the surfacereaction.

Sincea flow ratewasconstant,W/F wascontrolledby meansof the weightof pigment. If the relationshipis linearbetweenln[l•l-x)] andpigmentweight, the surfacereaction is first-order.For comparingreactionswith linalooland t-butyl alcohol,aseverything

exceptx is fixedin the respective reactions, a tentativereaction rateconstant, k' = 1n[1•1-•)], wasemployed.

For linalool,a reactiontemperature of 178øCwasused.In the caseof t-butyl alcohol,a

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JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS

relation betweenln[•-x)] and 1/T wasobtainedto calculatek' at 180øC. The ln[•-x)] of alcoholswascalculatedbasedon the 'recoveryas (1 - x).

RESULTS

AND

DECOMPOSITION

DISCUSSION

RATES OF LINALOOL

AND

t-BUTYL

ALCOHOL

OVER

PIGMENTS

Because linaloolis decomposed by quartzwoolabove200øCandits boilingpointis 198øC,we conducted the experimentfor linaloolat 178øC.Figure 1 showsthe relationshipbetweenthe amountof talcandk' for linalooldecomposition at 178øC.Since

0

) 0



I

,

10

20

Pigment Amount [mg] Figure 1. Test of first-orderreactionfor the linalooldehydrationovertalc.

DECOMPOSITION

OF LINALOOL

BY PIGMENTS

389

thereis a linearrelationship betweenthe amountof talc andk', dehydration of linalool is considered to be a first-orderreaction.Dehydrationof t-butyl alcoholwasmeasurable overa widerrangeof temperatures. Figure2 showsArrhenius'plotsfor the dehydration of t-butyl alcohol over seventypical pigments. Sincea linear relationshipwas recog-

nizedbetweenlog k' and I/T, k' for t-butyl alcoholat 180øCfor everypigmentwas calculatedusingtheseArrheniusplots.

TableII showsthe dataobtainedaslog k' for dehydration of t-butyl alcoholat 180øC

andlogk' fordehydration oflinalool at 178øC. A correlation wasfoundfor dehydration of t-butyl alcoholandlinaloolovertheseseven pigments(0.9226).

10.0

1.0

0.1

0.01 ¾/l

[] I

1.5

2.5

1/T

400

300

3.0

[ K

200

150

100

60

Temperature (øC) Figure 2. Arrheniusplotsof the dehydration of t-butyl alcoholovercosmetic pigments.--O--,

zinc

oxide;--I-linire; --0--,

kao-

, black iron oxide;--/X--, red iron oxide.

mica; --O--,

talc; --[•--,

ultramarineblue; --&--,

390

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table

II

Relationship Between theDehydration oft-ButylAlcohol andtheDehydration ofLinalool Dehydrationof linalool

Dehydrationof t-butyl alcohol

Pigments

x*

Zinc oxide Blackiron oxide Mica Talc Ultramarineblue Kaolinite Red ironoxide

0.10 0.40 2.40 69.20 10.90 99.99 74.90

k' 0.001 0.004 0.024 1.172 0.115 14.280 1.384

logk'

x*

k'

logk'

- 2.997 - 2.452 - 1.623 0.069 - 0.938 1.155 0. 141

13.5 42.5 65.5

0.145 0.553 1.064 1.387 1.687 5.297 4.603

-0.839 -0.257 0.027 0.142 0.227 0.724 0.663

75.0 81.5

99.5 99.0

* Linaloolrecoveryas (l-x).

Sincet-butyl alcoholis knownto be dehydratedoverBr6nstedacidsites,linaloolis also assumedto be dehydratedoverBr6nstedacidsites. IDENTIFICATION

OF THE

DECOMPOSITION

PRODUCTS

FROM

LINALOOL

Figure 3 summarizesthe decomposition reactionsof linalool, showingchemicalstructures for the suggestedintermediatesand the decompositionproductsformedover the cosmeticpigmentsusedin this study.Figure4 showsgaschromatograms for linalool afterreactionover 10 mg of ultramarineblue(A) andred iron oxide(B) at 178øC.The decomposition productsdiffer dependingon the nature of the pigment. Five peaks labelledI to V appearedand much linaloolremained.For decomposition by red iron oxide, the linaloolpeakwasnegligible.The samedecomposition products(I to V) for (A) were present,and, in addition, four new peaksappeared,VI to IX. This result suggeststhat additional decompositionoccurswith a pigment having strongeractivity such as red iron oxide.

PeakIX wasidentifiedasp-cymenebecause its massspectrumcontainedfragmentsat 119 and 91 within the parentpeakof 134 and the infraredabsorption spectrumcorrespondedto that of p-cymene.All otherdecomposition productsexceptIX hada parent peakat 136 and weresimilarto eachother.They hadfragmentpeaksat 121, 105, and 93, and thus they wereconsidered to be isomersof dehydratedlinalool(seeFigure 3 for structures).Similarity of the massspectraand differencesin the infraredabsorption spectrumof the C=C stretchingvibrationof the conjugateddoublebond at 1650 cm-1, aswell as the out-of-planecarbonhydrogendeformation vibrationfrom 1000

cm-• to 750 cm-1 and comparison with authenticsamples,suggested that II was cis-ocimene,oneof the two isomersof 3,7 dimethyl-l,3,6-octatriene,andthat III was anotherisomerof 3,7 dimethyl-1,3,6-octatriene,trans-ocimene.In the samemanner,I wasidentifiedas 7-methyl-3-methylene-1,6-octadiene (myrcene),VI and VII ascis-alloocimeneand trans-alloocimene,respectively,one of two isomersof 2,6-dimethyl-

2,4,6-octatriene.Furthermore,IV, V, andVIII wereassumed to becyclizedp-menthadiene, and VIII was identified as 1,3-p-menthadiene(alpha-terpinene),IV as 1,8-pmenthadiene(limonene),and V as 1,4(8)-p-menthadiene (terpinolene).Productswith MW = 138 were detected. However, thesewere not identifiable.

DECOMPOSITION

OF LINALOOL

BY PIGMENTS

391

OH +H +

(i)

ß

(iii)

(ii)

•L-H+ !1

IV Myrcene

cis-

trans-

Ocimene

Ocimene

,1-

cis-

AIIoocimene

iv)

-H+ V

Limonene

Terpinolene

• VII_

trans-

X

AIIooclmene •-Terpinene

p-Cymene

Figure 3. Mechanism andstructures of products formedby the decomposition of linaloolovercosmetic pigments. DISTRIBUTION

OF DECOMPOSITION

PRODUCTS

FROM

LINALOOL

BY PIGMENTS

Table III showsthe recoveryof linalool and the distributionof the decomposition

productsfrom linaloolat 178øCby 10 mg of the differentpigments.The recovery of linalool was obtainedfrom its calibrationline, and the distribution of the decomposi-

tion productswascalculatedfromthe peakareasof the decomposition productsrelative to the total area of the gas chromatogram.In Table III, pigmentsare arrangedin ascendingorderof the conversion rate. With pigmentsof low conversion rate, suchas

392

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS linalool

III

(A)

VIII

,(B). • IIV•1

Figure 4. Decomposition of linalooloverultramarineblueandredironoxidewith microcatalytic reactor at 178ø C. (A) Ultramarine blue. (B) Red iron oxide.

black iron oxide or hydratedchromiumoxide, only cis-ocimene,trans-ocimene,and myrcenewereformed.With thosepigmentsof moderateconversion rates,suchassilica and mica, limoneneand terpinolenewere alsoformed. With pigmentsof high conversionrates,suchasprussianblue and red iron oxide,cis-alloocimene, trans-alloocimene, alpha-terpinene,and p-cymenewere alsoformed. AMOUNT

OF THE

PIGMENT

AND

THE DISTRIBUTION

OF THE DECOMPOSITION

PRODUCTS

Figure5 showsthevariationin theyieldof thedecomposition products fromlinaloolby changingthe amountof talc. Myrceneplus ocimenegraduallydecreased asthe amount of talc increased.On the other hand, limoneneplus terpinoleneand alpha-terpinene showedlesschange,while alloocimeneandp-cymenegenerallyincreased,whichcorrespondswell with the factthat alloocimene andp-cymeneareformedoverthe pigments at high conversionrates. REACTION

OF LIMONENE

AND

TERPINOLENE

Table IV summarizesthe reactionof limoneneby thesecosmeticpigments.Examination of the data of TablesIII and IV suggests that thosepigmentsthat do not produce

DECOMPOSITION

OF LINALOOL

Table

BY PIGMENTS

393

III

Decomposition of LinaloolOver CosmeticPigmentsWith a MicrocatalyticReactor

Linalool

Product distribution (%)

recovery

Pigments

(%)

I

II

Zinc oxide Black iron oxide

86.5 57.5

nd 75.0

Hydratedchromiumoxide

54.0

73.3

nd

Cobalt blue Silica Mica Yellow iron oxide Talc Titanium dioxide A Ultramarine blue Titanium dioxide R Titanium dioxide A-R Ultramarine violet Prussian blue

34.5 23.0 34.5 15.0 25.0 20.5 18.5 9.5 7.5 2.5 1.0

64.3 50.0 43.6 43.7 19.4 26.2 46.2 24.0 20.9 25.4 10.0

11.9 15.6 12.0 12.5 12.9 12.3 14.3 15.6 6.8 10.9 6.9

VIII

IX

nd

nd

nd

nd

nd nd

nd nd

nd nd

nd nd

tr nd nd nd

tr nd nd nd

nd nd nd nd

nd nd nd nd

nd nd 6.10 nd

10.1 13.1

7.2 8.2

10.9 9.8

9.4 nd

tr nd

2.0 0.1

11.7 12.5

1.7 7.3

0.8 5.2

0.8 11.4

nd 10.4

nd nd

0.1 0.1

12.6 12.3 6.9 1.1 13.4

7.9 7.2 3.1 11.4 12.9

4.2 2.9 1.5 5.7 4.6

7.3 4.3 1.5 9.1 6.2

5.8 8.0 6.9 30.7 16.5

nd 7.2 30.8 11.4 8.8

24.0 4.4 24.7 12.5 6.7

III

IV

nd

nd

12.5

12.5 26.7

Kaolinire

0.5

7.9

1.1

Red iron oxide

1.0

11.3

7.2

V

VI

VII

nd

nd

nd

nd nd

nd nd

nd nd

16.7 21.9 25.6 16.3 14.4 12.3

7.1 12.5 10.5 22.5 13.7 18.0

nd tr 2.3 5.0

24.4 13.5

10.5 17.4 7.7 9.1 12.4

Other

Reactiontemp., 178øC; carriergas,N 2 50 ml/min;pigmentamount,10 mg;pulsesize,0.3 }xl;nd, no detectableamountof decomposition productfound.

limonenefrom linalooldo not changelimonene.The reactionproductsof limonene with thesepigmentsare the cyclizedterpenoidssuchas alpha-terpinene,gamma-terpinene, terpinolene,p-cymene,etc. Productssuchas myrceneand ocimenewere not detected,as in the caseof the reactionof terpinolenewith thesepigmentssummarized by TableV. This showsthat oncea terpenoidcyclizes,the ring doesnot reopen.Since limoneneisomerizes into terpinoleneand vice versa,asstatedby Wystrachet al., it is likely to occurby addition of a proton and formationof an intermediate(iv) (11). Thoughdecomposition of p-cymenewasinvestigated,it wasnot changedfurtherover any pigment. Therefore,p-cymeneis consideredto be the most stableof thesecompounds. DECOMPOSITION

MECHANISM

OF LINALOOL

OVER

COSMETIC

PIGMENT

Figure 3 summarizesa proposeddecompositionmechanismfor linalool over cosmetic pigments.First of all, linaloolformsan oxoniumion (i) by protonadditionin the same manneras notedwith t-butyl alcohol.The oxonlureion is then alehydrated to form a carboniumion intermediate(ii). Then, a protoncanbe eliminatedpreferentiallyfrom

the adjacentcarbonatomaccording to Saytzeffelimination,formingmyrceneand 3,7dimethyt-l,3,6-octatriene.However, due to the presenceof the doublebonds, two otherisomers,cis-ocimene andtrans-ocimene, form. When a pigmentof low activityis used, only thesethree compoundswill be produced.

Under morestringentpigments,an intermediate(iii) is producedby allyl rearrangement, which canform a cyclizedintermediate(iv), and then limoneneand terpinolene areproducedby protonelimination.It is knownthat suchallyl rearrangement is liable to proceedwhen linaloolchangesinto geraniol.

394

JOURNALOF THE SOCIETYOF COSMETICCHEMISTS 60

50

40

oxo 30

ß-

>-

20

10

I

I

!

i

50

70

Pigment Amount [mg) Figure 5. Relationship betweentheamountof talcandtheproducts distributionof linalooldecomposed at 178ø C. --O--, myrcene+ ocimene;--¸--, limonene+ terpinolene;--(}--, alloocimene;--O--, alpha-terpinene;--{)--, p-cymene.

Table

IV

Reactionof LimoneneOver CosmeticPigmentsWith a MicrocatalyticReactor

Limonene

Productdistribution (%)

recovery

Pigments

(%)

V

VIII

X*

IX

Other

Zinc oxide Black iron oxide

79.0 85.4

nd nd

nd nd

nd nd

nd nd

nd 100.0

Hydratedchromiumoxide

75.4

nd

nd

nd

nd

100.0

Silica

60.0

nd

nd

nd

nd

100.0

Mica Talc

nd 28.4

nd 34.4

nd 24.1

nd 12.9

Ultramarine blue Titanium dioxide A-R Prussian blue Kaolinite

87.5 16.2 87.0 25.0 16.7 7.5

nd 50.8 nd 16.0

nd 25.4 nd 26.7

nd 23.7 nd 8.4

nd nd

58.0 25.2

nd 0.2 nd 0.1 42.0 23.7

Red iron oxide

51.7

31.5

27.4

17.8

16.4

6.9

* 'y-Terpinene.

Reactiontemp., 178øC;carriergas,N2 50 ml/min; pigmentamount,10 mg; pulsesize,0.3 •1; nd, no detectableamountof decomposition productfound.

DECOMPOSITION

OF LINALOOL

Table

BY PIGMENTS

395

V

Reactionof Terpinolene OverCosmetic PigmentsWith a Microcatalytic Reactor Terpinolene

Productdistribution(%)

recovery

Pigments

(%)

IV

VIII

X*

IX

Other

Zinc oxide Black iron oxide

90.3 60.0

nd nd

nd nd

nd nd

nd nd

100.0 100.0

Hydrated chromium oxide

74.5

nd

nd

nd

nd

100.0

Silica Mica

95.8 97.1

nd nd

nd nd

nd nd

nd nd

100.0 100.0

Talc

18.7

nd

58.0

25.0

11.7

5.3

Ultramarine blue Titanium dioxide A-R Prussianblue Kaolinite Red iron oxide

94.1 61.3 38.1 22.6 66.1

nd nd 13.1 nd 21.7

nd 20.2 22.2 61.2 40.5

nd 28.4 9.1 26.6 21.7

nd nd 43.5 12.2 tr

100.0 51.4 12.1 tr 14.5

* •y-Terpinene.

Reaction temp., 178øC; carriergas,N2 50 ml/min;pigmentamount,10 mg;pulsesize,0.3 •tl; nd;no detectable amountof decomposition productfound.

Productionof geraniolby allyl rearrangement wasnot observedin theseexperiments, probablybecauseof the higher reactiontemperature.Limoneneand terpinolenecan rearrangeto alpha-terpinene throughan intermediate(iv) by the actionof acid. Limoneneand terpinolenedo not isomerizeto myrceneand ocimene.The cyclizedcompoundsultimately form p-cymenebecauseit is the most stablecompoundin this system.p-Cymeneis oneof the mostunpleasant odorsin deteriorated cosmetics. When p-cymeneis producedvia this scheme,dehydrogenation must occur. However, its mechanism has not been clarified.

During the degradationof uncyclizedterpenoids,alloocimene increases in content.As the positionof the double bond is closerto the centerof the molecule,it is more thermodynamically stable.Therefore,alloocimene is producedafterprolongedreaction. The odorof authenticsamplesof decomposed productswasevaluatedorganoleptically by a perfumer. Alloocimene,terpinolene,and alpha-terpinenehad camphoraceous odors,and p-cymenehad an unpleasant odor characteristic of deterioratedcosmetics. The further the decomposition of linaloolproceeds,the greaterthe unpleasantodor. Therefore, the changein odor may be estimatedby analyzingthe decomposition productsof linalool. Thus, the measurement of perfumedecomposition overcosmetic pigmentsusinga microcatalytic reactormay proveto be an importantmeansfor estimating the odor stability of cosmetics. ACKNOWLEDGEMENT

The authorswish to thank TakasagoCorp. for supplyingsometerpenoids. REFERENCES

(1) R. Ohnishi,K. Tanabe,S. Morikawa,andT. Nishizaki,Isomerization of 2-pinenecatalyzed by solid acids,Bull, Chem.Soc.Jpn., 47, 571-574 (1974).

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JOURNAL OF THE SOCIETYOF COSMETICCHEMISTS

(2) K. Arata,S. Akutagawa, andK. Tanabe,Isomerization of d-limonene oxideoversolidacidsand bases,J.Catal.,41, 173-179 (1976). (3) H. Pines,J. A. Vesely,andV. N. Ipatieff,Migrationof doublebondsin olefinic anddiolefinic

hydrocarbons catalyzed bysodium. Dehydrogenation ofd-limonene top-cymene, J. Am.Chem. Sot., 77, 347-348 (1955).

(4) G. Holzner,How accurate is an accelerated test?(comparative analyses concerning the stabilityof perfume oilsin accelerated test),Costa. & Perf.,89, 37-48 (1974). (5) H. Fukui,T. Saito,M. Tanaka,andS. Ohta, Catalyticactivityof pigmentsin cosmetics, Cosm. & Toil., 96, 37-46 (1981).

(6) H. FukuiandM. Tanaka,Catalytic activityofpigments. IV. Effects ofalkalimetalonacidicsitesof pigments, J. Jpn.Soc,Colour Material,56, 765-771 (1983). (7) H. Fukui,M. Tanaka,andY. Fujiyama,Catalyticactivityof pigments.V. Isomerization mechanism

ofpropylene oxideontitaniumdioxide, J. Jpn.Soc. Colour Material,57, 478-491 (1984). (8) H. Fukui,M. Tanaka,andM. Nakano,Polymerization of propylene oxideoverpigments,J. Jpn.Soc. ColourMaterial, 58, 640-647 (1985).

(9) D. W. Basserr andH. W. Habgood,A gaschromatographic studyof thecatalytic isomerization of cyclopropanea, J. Phys.Chem.,64, 769-774 (1960). (10) R. Namba,H. Fukui,andO. Nakata,Studies onapplication of gaschromatography/fourier trans-

forminfrared spectrometry. I Analysis ofdecomposition products oflinalool bypulse-reactor, Bunseki Kagaku, in press. (11)

V. P. Wystrach, L. H. Barnum, andM. Garber, Liquidphase catalytic isomerization ofot-pinene,J. Am. Chem.Soc., 79, 5786-5790

(1957).