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
386
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
388
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).
396
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).