T CEL

2R5;

.- V T

{In ‘

<2;

nu; Mammmmonflammmnm ‘

‘0
11'"
- ,

 

 

FEBIBZUOO

 

A STUDY OF

PEPPERKIKT OI L

A thee“ submitted to the faculty of lacing“
Stete callege 1n.pa311a1 fulfillment of the
requirements for the degree ot'flalter of

Science
Richard Walter Thompson
Deptrtment of Chemistry

1938

A Study of Peppermint Oil

1. Introduction

Eints have been known to the Eastern World since
the earliest times. Several. the identity of which is
mcertain, were used as spices or in medicine by the
Egyptiane(l). Hebrews (Z), and Romans (3). They seem
to have been put to similar uses by the barbarous
tribes dwelling east of the Rhine“). Charlemagne
mentions in his Capitulare three mints as worthy of
cultivation. -

(l) Schweinfurth. Berichte deutech. botan. Geaelleehaft
z (1884), 366.
(z) hath.,23:23; Luke, 11:43.
(3) Plinii. Eaturalis historiae libri.Lib.19. mpJ.
(40 Gildeneieter and Hermann. The Volatile Oils,
Vol. 1, p. 190.

331670

References to mints occur in the writings of the
abhess Hildegard. c.1160. The Berlin ordinance of 1574
mentions Oleun Henthae, and the hankfort list of 1583
mentions Olemn henthae, Oleum Polenii, and Glenn Pulegii.(l)
lhether or not peppermint corresponds to any of these
is a matter that can no longer be elucidated. The earliest
known specimens of Hentha piperita are those in the
British Ruseul in London, obtained by John Bay in
Hartfordshire in 1696(3). ‘ ' '

Cultivation of peppermint began in England about
1750, and reached its height a century later. after
which e. decline set in because of severe American con-
petition. Cultivation on the continent began not earlier
than in England.

Peppermint was groin in Japan much earlier than in
any other country. flourishing there long before the

(l) Gildemeister and Herman, The Volatile Oils,
'0101. p.19}.
(3) John Ray. Historic. Plantarm, 701.111. p.384.

Christian sra(l). nuckiger asserts that menthol was
extracted and used in medicine two thousand years agocz)‘.
then the distillation of peppermint oil began is not
known.

the production and distillation of peppermint oil
in the United ltates began in wayne County, Hes York.
early in the nineteenth century. Later the industry
oread to Hichigan. Indiana. Oregon, and California.
The united States is now the vorldls principal pro-
ducer. outside of Japan. and eighty to ninety percent
of the crop is grown in Michigan. -

Peppermint oils from different parts of the world
vary widely in fits their composition. Indeed. so my
factors are operative. soils. weather. fertilisers,
varieties. strains. time of harvesting. etc..-that
oils from a single area may show striking differences.
In gueral, however. uglish oil ccumands top prices,
with American oil second. and Japanese oil at the hot--
ton of the list. The last usually has a menthol con-

(1) Imperial Encyclopedia, 8th edition. Vol. 88. p.336
(2) shamans. (1391). p. 738

tent of eighty to ninety percent and is deficiat or
totally lacking in those couponents, especially the
esters. which impart that fine flavor so prized in the
sandy and gun industries.
The first thoroughgoing study of American pepper-

Isint oil vas carried out by Power and neber near the
end of the last century“). They exenined an oil dis-
tilled from the dry herb and identified the folloving
compounds:

Acetaldehyde

Acetic acid

A—pinene

L-limonene

Henthone

Menthyl acetate

Cadinene

leovalerianic aldehyde

" acid

Phellandrene

Cineole

iienthol

lienthyl i covalerianate

A nenthyl ester. 010319'033308
A lactone. 01031603

(1) Pharn. Rundeschau 12. (1894). 157

Anyl acetate (trace)
Dinethyl sulphide (trace) ’

For the present study, which was purely qualita-
tive and restricted to the isolation of the components,
and their identification, an oil was chosen which was
produced on a such soil in 193? in Ingham Comty. near
Lansing, dichigan.

3. Experimental

To separate the oil into its components, couples
were distilled in three ways: in vacuo, at atmospheric
pressure. and with steam. Case of the menthol was
removed, by cooling and crystallization. but this was
possible only when the more volatile capotmds had boa
distilled off. Atmospheric and stean distillation were
used but little, since these nethods cased too such
decouposition of the hydrocarbons present. When distilling
in vacuo, five degree fractions sell collected, and the
apparatus was so designed that each fraction could be
removed without breaking the vacuum. A fractionating
column over four feet long was used, and it was wrapped
with niohrome wire so that it could be heated elec-

tflcally e

Acetaldehyde

then a sample was distilled at atmospheric pres—
sure, a small portion came over between 30° and 110°.
A part of this was treated with sodium bisulphite. A
precipitate formed. but too little for identification.
Probably it was due to the presence of acetaldehyde or
nlerfnsldehyde or both. The possibility that the
precipitate was due to a combination with traces of
mthone in this fraction is excluded, because nan-
thone does not combine with sodium bisulphitefl).

Dinethyl sulphide

This fraction possessed a strong. disagreeable
odor, like that of dinethyl sulphide. When superin-
posed upon a .5 1!. solution of mercuric chloride in
a testtube. a white precipitate quickly formed at
the interface. This is the standard test for di-
nethyl sulphide in peppermint 011(2).

(1) Heueler and Pond, The Chemistry of the Terpenes.
p.398.

(3) Us BsWCia

Pinene

The fraction boiling at50-550/10nm. was purified
by repeated distillation. then distilled at atmospheric
pressure, and that portion boiling from 154 to 153°
collected, the boiling point of pinene being 156°.
Hany attempts were made to prepare the hydrochloride
after the method of Wallachu). but no solid derivative
could be obtained. The sample was carefully dried with
anhydrous capper sulphate or calcius chloride. Then
hydrochloric acid gas, prepared by dropping sulphuric
acid into a mixture of salt and concentrated hydro-
chloric acid, and dried by passing through sulphuric
acid,was passed into the sample, which was well cooled
by a freezing mixture.

It may be of interest to note in passing that
metallic sodium was tried as a dehydrating agent on a
few samples. In every case polymerisation to an orange
jelly-like use was the result. This is similar to the
action of sodium on isoprene.of which pinene may be re-
garded as the binolecnlar compound.

Pinene was finally identified by converting it to
the nitrosochloride(3). Equal parts of sample. ethyl

(l) Wallach, Annalen, 239, i.
(3) wallaoh and Otto, Annalen, 253. 251.

nitrite. and acetic acid were mixed and thoromly
cooled. Then concentrated hydrochloric acid was added
little by little. The crystals of pinene nitrosochlc-i
ride which quickly toned were filtered on 17 suction,
recrystallised from alcohol. washed with cold. alcohol,
and dried at 50°. The melting found .e. loo-102°.That
given is 109-111°(l). ' '
Equation for the reaction:
9'33 ' :53
6

3:0/ \ ' oso/ °\cs01\/°a 3

:\ 3 + H001
\OI!//GH

ca
. ,

9‘3 Hg 0\ /OHZ J%Ofia
Pinene ° Pinens nitrosochlorid'e
The ethyl nitrite used in this derivative we.

 

 

prepared by dissolving twenty-Jive grass of sodium

nitrite in a mixture of one hundredcc. of water and

ten grams of alcohol contained in a three-neck flash.

from a dropping funnel a solution of twenty grams of
hundred

sulphuric acid in oneAiifty cc. of water and ten grams or

alcohol was added in a thin stream. The ethyl nitrite

distilled off as it formed and was collected in a flask

cooled with ice. It was then ready for use without fur-

(1) Annalen, 253, 251.

ther purification.

Henthene

A menthene boiling it 167-80 has been found in
Russian peppermint oil by Andres and Andrea: To deter-
mine if it occurred in American oil. the fraction boil-
ing at55-580/10mm. was taken. “We cc. of hydrochloric
acid in two cc. of glacial acetic acid was added slowly
to a well cooled mixture of five cc. of sample. five cc.
of glacial acetic acid. and four cc. of ethyl nitriteuo.
But no crystalline derivative could be obtained.

Cineole

The fraction boiling at 58-63°[1m.’.’ . ‘ gsas dis-
tilled repeatedly in vacuo. and finally a portion boil-
ing at l?5—l78°(atnospheric) was tested for cineole.
Pure cineole boils at 176°(8). in attempt was made to
prepare the addition product of cineole and iodol(3).

(l) Sicker and Xremers, Amer. Chem. Journ.. 14, 293.

(3) Heusler and Pond. The Chemistry of the Terpenes,
p.524.

(3)Hirschsohn, Pharn. Zeitschr.f. Russ)... 33,49.

10
is no iodol was available. it was necessary to prepare
it from pyrrole. But only a gram or two of this was
on hand, andrthe yield of iodol was so small thsi no
crystals of the derivative were obtained. V t

The hydrdbromids was then resorted to. Into a'
Hurts flash fitted with a dropping funnel were placed
one part of red phosphorus and two parts of water.
Bromine was then added drapwise from the funnel and
the hydrobrcmic acid gas formed was passed through a
U-tube containing red phosphorus to remove bromine
taper and through a U-tube containing calcium chloride
to reoove moisture. when the dried gas was admitted to
a flask containing a petroleum ether of sanple. well
cooled by’aifreesing'nixture. s'heayy'white precipitate
formed immediately. This was filtered. washed with
petroleum ether.and dried vith suction. Decomposition
was so rapid that it was never possible to reorystal- ,
lies the product and very difficult to dry it properly.
The melting points found fordifferent samples were
43°, 52.530. 56-58°. and 53-600. That recorded in the
literature is 58-5700).

11) Heusler and Pond, The Ohenistry of the Terpenes.
p. 336.

11
Equation for the reaction:

9‘3 9st
0 0-31:
1130 ORB H30 an
i c ' +ssr__.> . 03
so so
2\|/ s 2\ /032
9 as
sc-cacs 30-0-
3 H 3 3 3 cas
L-linonens

The cineole fraction was tested also for limnene.
in three ways. Linonene boils at l?5-l?7°(l).

The nitrosochloridc method of wallachm) was not
successful. To a mixture of five cc. of sample, eleven
cc. of ethyl nitrite, and twelve cc. of glacial acetic
acid. cooled with ice and salt.was added a mixture of
six cc. of hydrochloric acid and six cc. of glacial acid.
slovly and in small portions. rineny five cc. of ethyl
alcohol was added. and the mixture was allowed to stand
for some time in a freezing mixture. But no crystals
formed.

in attempt to prepare the tstrabronide using the
procedure of Power and neber was likewise msuccessfultz).

(l) Heusler and Pond. The chemistry of the Terpenes, p.73.
(3) innalen, 253, 108; 270, 174.
(at Pharn. Rundschau, 13, (1894), 160.

13
_The sample was added drapwise to a cooled mixture of
bromine and acetic acid until only a slight excess of
« bromine remained. The solution was then decolorized
with.an aqueous solution of sulphur dioxide. and water
‘was added to precipitate the bromide. But again.no cry-
stals developed. Power'and Kleber claimed that in
this way the formation of hydrobromic acid and.of‘un-
crystallizable bromides of isomeric terpenes was in-
hibited.

The only method found which would yield a solid
derivative was that of Wallach, and this was successful
but once. The sample was purified as much as possible
and diluted with.four times its volume of glacial I
acetic acid. To the solution, cooled with.ice. bromine
was added from a medicine dropper as long as it was
absorbed with decolcrization. After'standing for
several days. a few crystals were observed, the melting
point of which was 93-1000, no attempt being made to
recrystallize them. The melting point recorded is 104
to 105°(l).

(l) Heusler and.Pond, The Chemistry of the Terpenes,
p.73.

13

Equation for the reaction:

CH
. 3 (.733
O r
H? 9113 H03:- 083
H30 \ mg + 281.3 323 / 333
f \s
HEB- Q3083 HzO‘3‘CHzBl'
. r
Lolinonene Linonene tetrabronide

Phellandrenes

The cineole and linonene fraction was further
tested for the presence of phellandrenes. the or-modi-
fication boiling at 11750, and the: fi-fom at 171°. A
solution of five grams of sodium nitrite in eight
grams of water was placed beneath a layer of five cc.
of sample in ten cc. of petroleum ether contained in a
testtuhe. Then five cd. of glacial acetic acid was
added with shaking to release nitfious acid“). Al-
though this procedure was repeated on many samples,
no crystals of nitrosite were ever obtained. Il'he
nitrcsite is the only solid derivative of phellandrsne
known.
(1) Wallach and Gildemsister, Annalen. 246, 283.

14

These results would seem to indicate that phellanc
drsne was not present in the oil examined. Yet whenever
a fraction boiling at 58—639/lOmn. was afterward dis-
tilled at atmOSpheric pressure. it rapidly turned from
colorless to s. deep red. is cineole and linonene are
stable compounds and can be distilled at ordinary pres-
sures without decomposition. while phellandrene with
its conjugated system of double bonds is among the
most unstable of the terpenesu), it nay be assured that
thss: compound” was present. Probably the failure to
prepare the nitroeite was due to insufficient purifi-

cation.

itsnthsne

Hort to menthol, nenthone is the most abundant
constituent of peppermint oil, occurring in amounts as
high as twenty percent. is it boils at BOT-208°, and
menthol st 313-215", the two cannot be separated by dis-
tillation. However by cooling the fraction boiling with-
in this range to a point well below freezing. it was
possible to crystallize out a large part of the menthol.
which was rmved by filtering with suction as rapidly
as possible.

(1) Heusler and Pond, The Oheaistry of the Terpenes.
p. 109.

15

Hany attempts were made to prepare the crime of
leathone. using the method of .Bccmannu). A menthone
sample was dissolved in three times its weight of ninety
percent alcohol. and powdered.hydroxylamine hydrocthride
was added in an amount about 1.3 times that required by
the equation. Then during ten minutes a little sore
than the theoretical amount of sodium bicarbonate was
added in small portions to neutralize the acid and re- '
lease the hydroxylamine. After standing thirty minutes
with occasional stirring the mixture was poured into
cold water and stirred vigorously. But nocrystals of
the crime were ever obtained by this method or vari-
ations of it. nor could the ox ime be gained by shak-
ing out of ethereal solution with dilute sulphuric
acid. The references on this procedure. however, were
not available“).

The dibromo derivative was tried(3). Two mole of
bromine was added to one mol of the menthone fraction

dissolved in chloroform at room temperature. But

(1) Annalen, 350. 329.

(a) Bechnann. Journ.f.Praht.Ghen..II. 55,(1897). 1?.
y 0., (1887). 1375. 1461.

(3) Buchanan and tichelberg, Ber..zs. 418.

16
addition of alcohol did not cause any precipitation. If
too much bromine was used. other crystalline products
should have formed, but none was observed.

Finally natau's method for the preparation of the
semioarbasone was tried‘l). issuing the sample to be ..
two-thirds menthcne. the theoretical amount of semicar-
buize was dissolved in a little water. corresponding .
amounts of sample and of potassium acetate were then dissolved
in a mixture of alcohol and water. The two solutions were
then mixed and filtered. In the filtrate, small needles
of the semicarbazone were soon observed. These were re-
moved and recrystallised three times from boiling alcohol.
After drying, the melting point was found to be 175°. five
more recrystallisations raised the melting point to l??-'
178°. The value recorded is 178°“).

squaticn for the reaction:

933 \ 338 ' 933 1532
CE 0:0 OH 0:0
/ \ i / \ .
320 , 033. , HE 330 . 0‘33 m
t I + t _____.> O t !
ago one m3 see c r: E
/. . .9
\gm , \9{
a a - c .. as H o -* c s- OH
3 s 3 3 s, s

henthcne ' ' Mienthone semi carbazone

(1) Bulletin do la Societe Chimique, 3,'19, 788.
(2) Heusler mid Pond, The Chemistry of the Terpenes. p.303.

l?

meenthol

Menthol costituted about fifty*percent of the oil
examined. and was readily obtained‘by freezing oil from
which the more volatile components had.been removed.
then recrystallized'from chloroform,,it melted at 43.430,
which is the value recorded in the literature(l). For a
derivative the‘benzcate, melting'at 53-54°. was chosen.
Hehthol and benzoic anhydride were heated together in a
bomb tube fcr three hours at 1600(2). After cooling, the
reaction mixture solidified to a yellow. crystallhne
mass according to expectations. unfortunately. after boiling
with sodium carbonate solution to neutralize excess‘bsn-
soic anhydride; dissolving in ether snd'shaking with
cold, dilute sodium hydroxide solution; separation; and
evaporation of the Other, the bsnsoate did not crystallize
again, and only a yellow oil remained.

Dimenthyl sulphite was then tried(3). unlike almost
all other solid derivatives of menthol, this does not

(1) Heueler and Pond. The Chemistry of the Terpenes, p.309.
(3) Beckmann. innalen. 263,31.
(3) Kenyon and Pickard, J. Chem. 80s.. 10?, p.45.

18
require a high temperature for its preparation, and in

fact must he prepared Itt a temperature below 6°. Equiva-
lent amounts cf thionyl chloride and menthol. each diluted

with a large volume of petroleum ether, were slowly mixed
and allowed to react at slow temperature. The product was
then separated from unchanged menthol by fractional dis-
tillation in vacuo. Dinenthyl sulphite boils at 310°l953.
and solidifies to a white mass, which crystallizes
readily from dilute alcohol '-in needles which melt at 52°.
The value found was 50-52".

Ecuaticn for the reaction:

333 9H3 933
CH . w .

a s \\\OH H o//’ ‘\\ca H c’/’ \\\ca
3 3| 0 3.. ' 3: o 3 20‘ o 3
H C 0303 + 30 ‘9 Hflc (SHOE-GHQ CI"?

. 3 \\\ /// . . €33 “ //r s \\\ //’ 2
23 9H: 0 93
H 0-0-03 H 0-0-03 H 0-6-03
3 H p 3 3 H 3 3 H 3
hienthoi Dimenthyl sulphite I
Esters

An effort was made to obtain the saponification num—
bers of the fractions boiling at lot-112°Iiomm. and at
izrgieo°l10mm.. as menthyl acetate boils at 109°IlOmm.
and menthyl isovalerianate at 135.127°/10m. These fractions

19
were redistilled many times, but as is shown by the
data were even.then far from pure. Yet. as these fractions
were not acid'to litmus or phenolphthalein before saponi-

fication. the data reveals that esters were present.

normality cf’sto4 solution .2545

' " XOR ' .4510
traction Acetate lscvalerianate
GI. of sample 1.0326 0.9993
as. ' 203 25.24 26.31
Os. ' 8280‘ to neutralize 38.66 37.86
Camillicqt. 108 11.38 11.83

' H3604 9.83 8.64

’ 203 to sapcnify 1.55 3.18
Baponification No. found 84.1 123.3

’ ' calcd. 880 231

In.order to identify the acid radicals. about one
gram of the potassium salt was placed in a small flask
with.the theoretical amount of thionyl chloride and heated
gently for thirty minutes under a reflux condenser. The
cooled residue sac then treated with two nols of’p-tolu—
idine dissolved in thirty cc. of benzene and refluxed

a few minutes. Finally the benzene solution was washed

30
with water, dilute acid. dilute alkali. and again with

water. filtered, and evaporated to drynessu). But the

recrystallizing medium. methyl alcohol, yielded no
crystals for either ester, and so the presence of

neither was proved.

Oadinene

The highest boiling motion, from 130 to 1480/mm.
was tested for cadinene, 0151134. a sssquiterpene con-
taining two conjugated double bonds. the exact position
of which ha never been determined. The compound boils
at 274-875°/atmospheric(2). 1t oxidizes very rapidly
in the air. and when distilling in mono a stress of
inert gas. rather than air. should be used to prevent
bumping. Many attsmts were made to obtain the dihy'dro-
chloride of this compound“), one volume of sample being
mixed with twa vclmes of flaciagligcfid. s. fairly rapid
stream of hydrochloric acid gas passed in. and the mix-
ture ‘tept at or near 0° for two days. but a crystalline

derivative was never obtained. Yet the boiling point of

' (1) rm, Qualitative Organic Analysis. p.177.
(2) Hoosier and Pond, Chemistry of the i'srpenes. p.415.-
(3) J. aha. Ice.. 1934, 13.1993.

the fraction and. the fact that a large amount of
decomposition occurred whenever it was distilled in
the air met that «dim was probably present.

Residue

a. residue. after all the dioramticned frac-
tions were collected. was s resinous mass of a deep
crangs-red color. consisting largely of oxidation
products and polymers of phellandrene and codincne.

3. conclusion

A qualitative study of nichigan peppermint cii
proved the presence of several chemical commands.
Evidence was found or the presence of several

Other . e

23

References

Heuolor and Pond, The Chemistry of therorpeneu-

Glldemeister and Hoffman. The Volatile Gila

Parry, The Chemistry of the Essential Oils

Fisher, Laboratory manual of Organic memietry

lam, Qualitative Organic Analysis

Schlmmel & so... m1 Reports on Essential Oils

8. 8.3macopeia

Annalen Chem.

Amerioau chemical Journal

Bulletin de la. Societc ’cmmaque

Journal fur Praktlsche Chemo

Beridhte

Journal of the Goa-nice]. Society

 

 

nICHIcaN STATE
llHHIIIIHI!>II\!IIM\\|IIII
3129301

 

  

    

V.

W ulnujfijfijflfs

(35377