Raphael Meldola.

The chemical synthesis of vital products and the interrelations between organic compounds online

. (page 22 of 55)
Online LibraryRaphael MeldolaThe chemical synthesis of vital products and the interrelations between organic compounds → online text (page 22 of 55)
Font size
QR-code for this ebook

mann, loc. cit,; Knoevenagel, loc. cit.
1085; K. and Klages, Ann. 281,97). The
latter forms a dibromide (Hagemann,
loc. cit. 884; Knoevenagel, loc. cit.
195^)^ which readily decomposes into
hydrogen bromide and m-cresol (K.

Acetoacetic ester through its methyl-
ene derivative can also be converted by
the action of ammonia under various
conditions into dihydrolutidine-dicarb-
oxylic ester (Knoevenagel and Klages,

Digitized by




Ann. 281^ 96 ; SchiS and Prosio^ Gazz.
26^ 70 : see also Griess and Harrow, Ber.
21, 2740). The latter on heating with
alcoholic potash gives the above methyl-
cyclohexenone among other products
(S. and P. loc. cit. 76), and this can be
converted into m-cresol as before.

[D.] Prom naphthalene [12] through
o-toluic acid (see under benzyl alcohol
[64 ; B] )y and from the latter as under A.

Phthalic acid may also be converted
into phthalimidine {loc, cil,), the latter
nitrated (Honig, Ber. 18, 3447), reduced
to 5-amino-o-toluic acid by heating with
hydriodic acid and phosphorus (Ibid.
3449), and the latter converted into
5-hydroxy-o-toluic acid and m-cresol as
under A.

Also from naphthalene through the
trisulphonic acids (heteronucleal) derived
from the m-disulphonic acid, which, on
fusion with alkali, give m-hydroxytoluic
acid and m-cresol (Kalle & Co., Germ.
Pat. 81484 of 1894; Ber. 28, Ref. 694 ;
also Ref. 364). The 1 : 6-dihydroxy-
naphthalene-3-sulphonic acid on fusion
with alkali gives the corresponding
trihydroxynaphthalene, which yields m-
cresol on further heating (KalJe & Co.,
Germ. Pat. 1 1 2 1 76 of 1 899 ; Ch. Centr.
1900, 2, 700: see also Ber. 28, B;ef.
671 and 693, relating to Germ. Pats.
81281 and 81333 of 1893 of Meister,
Lucius, and Briining, and also Ch. Centr.
1897,1, 1039). ^ ^ ^ .

[B.] Orl/focresol [61] on heatmgwith
ammonium chloride and ammonio-zinc
chloride at 330-340'' gives o-toluidine
(Merz and Muller, Ber. 20, 547). The
latter can be converted into o-toluic
acid, and m-cresol as under A.

Or o-toluidine may be acetylated^
nitrated, hydrolysed, and thus converted
into 5-nitro-o-toluidine (Beilstein and
Kuhlberg, Ann. 168, 345), from which,
by the diazo-method, m-nitrotoluene can
be obtained (Ibid.), and from this m-
toluidine. The latter might be directly
converted into m-cresol by the diazo-
method, or indirectly through m-toluic
acid, &c., as under A.

[P.] Paracresol [68] on nitration
gives 3-nitro-p-cresol (Armstrong and
Thorpe, B. A. Rep. 1875, 112; Hof-
mann and Miller, Ber. 14, 573 ; Stadel,

Ann. 217, 53 ; Frische, Ann. 224, 138),
which, by heating with ammonia, gives
3-nitro-p-toluidine (Barr, Ber. 21, 1543).
The latter can be converted into m-
nitrotoluene, m-toluidine, and m-cresol
as under A.

[O-.] From benzoic aldehyde [114]
through the m-nitro-derivative, m-tolui-
dine (see under phenol [60 ; H]), and
then as above.

[H.] From thymol [67] by heating
with phosphorus pentoxide and decom-
position of the m-cresyl phosphate by
heating with alkali (Engelhardt and
Latschinoff, Zeit. [2] 6, 621; South-
worth, Ann. 168, 268 ; Stadel and Kolb,
Ann. 260, 209 ; Tiemann and Schotten,
Ber. 11, 769).

Or thymol can be converted into
thiothymol by the action of phosphorus
pentasulphide (Fittica, Ann. 172, 328),
3-sulpho-p-toluic acid by oxidation of
thiothymol with nitric acid (Ibid. 329),
and then through 3-hydroxy-p-toluic
acid and m-cresol as under A.

[I.] From menthone [120], which gives
tetrabrom-m-cresol among the products
of the action of bromine. The t^tra-
brom-derivative gives m-cresol on reduc-
tion with sodium in alcoholic solution
(Baeyer and SeufFert, Ber. 84, 40).

[J.] From pulegone [128] through
methylcyclohexanone (see under phenol
[60; S]). The latter gives m-cr^l
on treatment with a chloroform solution
of bromine (Klages, Ber. 82, 2567 :
see also Wallach, Ibid, 3338).

63. Paracresol; 4-MetliylplieiioL

Natural Sources.

Occurs as a salt of cresylsulphuric
acid in urine of herbivorous animals,
and, in certain diseases, in human urine
(Baumann, Ber. 9, 1389; Stadeler,

Digitized by





Ann. 77, i8 ; Brieger, Zeit. physiol.
Ch. 4, 204: see also under o-cresol
[ei] for further references).

A product of putrefaction of animal
proteids (Baumann and Brieger, Zeit
physiol. Ch. 8, 149; Ber. 12, 706), of
p-hi/droxyphenylacetic and hydroparacou-
marie acids [Vol. II] (Baumann, Zeit

fihysiol. Ch. 4, 304), and of tyrosin
Vol. II] (Weyl, Zeit physiol. Ch. 3,
312; Baumann, Ibid. 4, 304).

The p-cresol complex may be con-
tained in podocarpic acid, which con-
stitutes the chief portion of the resin
of Podocarpns cupressina, var. imbricata
(Oudemans, Ann. 170, 259).

The methyl ether appears to exist in
the perfiime 'Cananga Essence ' (ylang-
ylang) from Cavanga odoraf^ (Reychler,
Bull Soc [3] 13, 140). p-Cresyl
acetate exists also in this oil (Darzens,
Bull. Soc. [3] 37, 83).

Synthetical Processes.

[A.] From toluetie [64 ; A, fee]
through p-nitrotoluene (see under ortho-
-cresol [ei; A]), p-toluidme by reduction,
and thediazo-reaction with latter (Griess,
Jahresber. 1866, 458; Komer, Zeit
[2] 4, 326).

Or p-nitrotoluene on mild reduction
gives p-toluylhydroxylamine (see under
toluquinol [72 ; A]), and this gives
p-cresol among the products of decom-
position by hot dilute sulphuric acid
(Bamberger, Ber. 28, 246 ; for produc-
tion of p-toluylhydroxylamine by the
oxidation of p-toluidine by monoper-
sulphuric acid see Bamberger and
Tschimer, Ber. 82, 1677).

Or from toluene through the p-sul-
phonic acid and potash fusion of the latter
(Wurtz, Ann. 144, 122; 166, 258;
Engelhardt and Latschinoff, Zeit [2]
6, 618).

From toluene through m-xylene (see
under orthocresol [61; A]), m-xylene-
4-sulphonic acid by sulphonation (Jacob-
sen, Ann. 184, 188; Ber. 10, 1015;
U, 19), and potash fusion of latter so
as to form 4-hydroxy-m-toluic (a-cre-
sotic =p-homosalicylic) acid (Engelhardt
and Latschinoff, loc, cif. 712). The
latter acid on heating with strong


hydrochloric acid at 180-185** gives

Or m-xylene may be oxidised to m-
toluic acid (Tawildaroff, Zeit [2] 7,
419; Ber. 4, 410 ; Briickner, fier. 9,
406 ; Renter, Ber. 17, 2028), the latter
brominated (Jacobsen, Ber. 14, 2351),
and the 4-brom-m-toluic acid thus
formed fused with potash (Ibid.),

Or m-toluic acid may be sulphonated
(Jacobsen, loc. cit. 2355^, the 4-sulpho-
m-toluic acid converted mto 4-hydroxy-
m-toluic acid by potash fusion (Ibid.),
and then into p-cresol as before.

Or m-toluic acid may be nitrated
{Ibid. 2353), the 4-nitro- reduced to the
4 - amino - m - toluie (methylanthranilic)
acid {Ibid.), the latter converted into 4-
hydroxy-m-toluic acid by the diazo-
reaction {Ibid. : see also Panaotovic,
Joum. pr. Ch. [2] 33, 64), and into
p-cresol as before.

Or m-xylene-4-sulphonic acid (see
above) may be converted into 1:3:4-
xylenol by potash fusion (Jacobsen, Ber.
U, 28), or the corresponding 1:3:4-
nitroxylene into 1:3 :4-xylidine and into
the same xylenol by the diaZo-reaction
(Harmsen, Ber. 18, 1558). This 1:3:4-
xylenol (or its )8-sulphonic acid) gives 4-
hydroxy-m-toluic acid by potash fusion
(Jacobsen, Ber. 11, 375 ; Ann. 196, 283),
and this gives p-cresol as before.

Toluene may also be converted into 2 :
4-dinitrotoluene (Deville, Ann. 44, 307),
the p-nitro-group in the latter replaced
by bromine (Beilstein and Kuhlberg,
Ann. 168, 340), the 4-brom-2-nitro-
toluene heated with alcoholic potassium
cyanide at 220°, and the nitrile hydro-
lysed to 4-brom-m-toluic acid (Richter,
Ber. 6, 425), which can be converted
into 4-hydroxy-m-toluic acid and p-
cresol as above. 4-Brom-2-nitrotol-
uene is also formed (with 4-brom-3-
nitrotoluene) by the nitration of p-
bromtoluene (Wroblewski, Ann. 168,


Or toluene may be converted into
methyl-m-toluyl ketone by the action
of acetyl chloride in presence of alu-
minium chloride (Essner and Gossin,
Bull. Soc [2] 42, 95) ; or p-bromtoluene
into p-bromtoluyl-m-methyl ketone by
the same process. The latter on oxida-

Digitized by




tion with potassium permanganate gives
4-brom-m-toluic acid (Claus, Journ. pr.
Ch. [2] 46, 21), and this can be con-
verted into p-cresol as before.

Toluene or m- or p-xylene can, by
further methylation, be converted into
pseudocumene = i : 2 : 4-trimethylben-
zene (Fittig and Ernst, Ann. 139, 187 ;
Fittig and Jannasch, Ann. 161, 286;
Fittig and Laubinger, I6id. 257 ; Jan-
nasch, Ann. 176, 286; Friedel and
Crafts, Ann. Chim. [6] 1, 461 ; Ador and
Rilliet, Ber. 12, 329), the sulphonic acid
of which (Jacobsen, Ann. 184, 199)
gives a sulphonamide, which, by oxida-
tion with alkaline permanganate, g^ves
4-sulphamidemethylbenzene-2 : 5-dicarb-
oxylic (methylterephthalic = a-xylid-
ic) acid (Jacobsen and Meyer, Ber.
16, 190). The latter (sulphamide) on
potash fusion gives methyl-4-phenol-
2': 5-dicarboxylic (s-hydroxy methyltere-
phthalic) acid (Ibid.), and this on heat-
ing with lime gives p-cresol.

NoTB : — ^All generators of toluene thus become
generators of p-cresoU

[B.] From p-hydroxyiyhenylacetic acid

[Vol. Ill by heating with lime (Sal-
:owski, Ber. 12, 1440).

[C] From acetone [106] through
mesitylene (see under Tbenzyl alcohol
[64 ; D]), mesitylenesulphonic acid
(Jacobsen, Ann. 146, 95), 4-hydroxy-
mesitylenic (i : 3-dimethyl-4-phenol-5.
carboxylic) acid by potash fusion of the
sulphonic acid (Fittig and HoogewerfE,
Ann. 160, 333), 4-hydroxyuvitic (4-
methylphenol-3 : 5-dicarboxylic) acid by
potash fusion of hydroxymesitylenic
acid (Jacobsen, Ann. 196, 285), and
decomposition of the hydroxyuvitic acid
by heating with hydrochloric acid at
200° {Ibid. 206, 196).

Or from mesitylene through mesityl-
enic acid (see under o-cresol [61 ; B]j,
4-nitro- and 4-aminomesitylenic acid
(Schmitz, Ann. 193, 162; 171), 4-hy-
droxymesitylenic acid by the diazo-reac-
tion (Jacobsen, Ber. 11, 2055), and then
4-hydroxyuvitic acid and p-cresol as

Or 4-hydroxymesitylenic acid may
be converted into 1:3: 4-xylenol by
heating with hydrochloric acid at 200°

(Jacobsen, Ber. 11, 2052 ; Fittig and
HoogewerfE, Ann. 160, 330), and the
xylenol converted into 4-hydroxy-m-
toluic acid and p-cresol as under A.

Or mesitylene may be converted into
mesitol (1:3: 5-trimethyl-2-phenol) by
potash fusion of mesitylenesulphonic
acid, or by the diazo-reaction from
aminomesitylene (Biedermann and
Ledoux, Ber. 8, 59 and 250; Jacob-
sen, Ann. 196, 268). Mesitol on potash
fusion g^ves 4-hydroxyme8itylenic acid
(Jacobsen, loc, cit. 274), from which
p-cresol can be obtained as above.

Or from mesitylenic acid through
a-sulphomesitylenic acid by sulphona*
tion (Remsen and Brown, Am. Ch.
Joum. 8, 218), 4-hydroxymesitylenic
acid by potash fusion (Ibid, 220), and
then as above.

Or mesitylene may be oxidised to
uvitic acid (see under benzyl alcohol

(64; D]), which, by distillation with
ime, gives m-toluic acid (Bottinger and
Ramsay, Ann. 168, 255). The latter
can be converted into 4-hydroxy-m-
toluic acid and p-cresol as under A.

Note : — Generators of mesitylene and uvitio
acid (see under benzyl aloobol [54 ; D to Q])
thus also become generators of p-cresol.

Acetone may also be converted
through phorone into pseudocumene
(see under o-cresol f61; B]), and the
latter into s-hydroxymethylterephthalic
acid and p-cresol as under A.

[D.\ Parahydroxyhenzoic aldehyde
[119] gives, among other products, p-
cresol when heated with acetic acid and
zinc dust (Tiemann, Ber. 24, 3170).

[B.] Metacresol [62] on nitration
yields a mixture of 4- and 6-nitro-m-
cresol (Stadel, Ann. 217, 51 ; 269, 210).
The etnyl ether of the former gives, on
heating with strong aqueous ammonia
at ii^o-i5o'*, 4-nitro-m-toluidine (Stadel
and Kolb, Ann. 269, 224). The latter
on replacement of the NHg-group by
hydrogen by the diazo-method would
give p-nitrotoluene, which can be con-
verted into p-toluidine and p-cresol as
under A.

[P.] Anethole [68] when heated under
pressure to 250-275 gives, among other
products, p-cresol methyl ether (Orn-

Digitized by


68 p-e4 a]

dorff, Terrasse, and Morton, Am. Ch.
Journ. 19, 845).

Note : — ^Paracresol can be converted into p-
cresylsulphuricacid (potassium salt) by heating
the potassium salt with a solution of potassium
pyrosulphate (Baumann, Ber. 9, 1389).

64. Phlorol; 2-EthylphenoL

Natueal Souucbs.

The phlorol complex probably occurs
in gum-ammoniac, the dried sap of
Borema ammoniacumy which yields
phlorol methyl ether on distillation
with zinc dust (Ciamician, Ber. 12,

Hlasiwetz obtained a phlorol by dis-
tilling barium phloretate with lime
(Ann. 102, 166), but since phloretic
acid is a para-hydroxybenzene deriva-
tive, it is doubtful whether the phlorol
thus obtained is the ortho-ethyl phenol,
although Oliveri concludes that it is
identical with this modification (Gazz.
13, 263).

Synthetical Processes.

[A.] Benzene [6 ; I, fee] can be con-
verted into ethylbenzene by several
processes : —

By the action of sodium on a mixture
of brombenzene and ethyl bromide (Fit-
tig, Ann. 131, 310; 133, 222; 144,
278; Schramm, Ber. 24, 1333).

From benzene, ethyl iodide, bromide
or chloride, and aluminium chloride
(Friedel and Crafts, Ann. Chim. [6]
1> 457; Sollscher, Ber. 16, 1680 ;
Sempotowski, Ber. 22, 2662; B^hal
and Choay, Bull. Soc. [3] 11, 207;
Radziewanowski, Ber. 27, 3^*35).

From benzene and ethylene in the
presence of aluminium chloride (Bal-
sohn. Bull. Soc. [2] 81, 540), or by
heating benzene witn ethyl ether and
zinc chloride {Ibid, 82, 618).

From benzene and chloracetic or
chloroformic ester and aluminium
chloride (Friedel and Crafts, Aun. Chim.



[6] 1, 527; Rennie, Trans. Ch. Soc.

41, 33)-

From benzene and ethylene through
thedibromideof thelatter, vinyl bromide,
and the action of the latter on benzene
in presence of aluminium chloride (An-
Bchiitz, Ann. 236, 331).

Ethylbenzene when brominated (in
the dark) in presence of iodine gives a
mixture of o- and p-ethylbrombenzene
(Schramm,Ber.l8, 1273; Sempotowski,
Ber. 22, 2668). The latter on sulphona-
tion yields 'ethyl-4-brombenzene-2-sul-
phonic acid (Sempotowski, loc. ciL),
which on debromination by zinc dust
and ammonia gives ethylbenzene-o-
sulphonic acid {Ibid). The latter yields
phlorol on fusion with potash (Beilstein
and Kuhlberg, Ann. 166, 211 ; Sempo-
towski, loc, cit, 2672).

Or ethylbenzene may be nitrated,
the o-nitro-derivative reduced, and the
amino- ethylbenzene converted into
phlorol by the diazo-method (Suida and
Plohn, Monats. 1, 175; B6hal and
Choay, Bull. Soc [3] 11, 209 ; Sempo-
towski, loc, cit. 2672 ; for nitration of
ethylbenzene and separation of isomer-
ides see Schultz and Flachslander,
Journ. pr. Ch. [2] 0Q, 153).

[B.] From gtyrene [7] through ethyl,
benzene by heating with hydriodic acid
(Berthelofc, Bull. Soc. [2] 9, 455), or by
passing the vapour mixed with hydrogen
over heated copper (Sabatier and Sen-
derens, Comp. Rend. 130, 1761 ; 132,
1254; 134, 1 1 27). Also by reduction
with sodium in alcoholic solution
(Klages and Eeil, Ber. 36, 1632), and
then as under A.

[C] Phenol [60] when heated with
absolute alcohol and zinc chloride gives
a mixture of ethylphenols (Auer, Ber.
17, 670 ; Errera, Gazz, 14, 484), among
which phlorol is present-
er phenol may be converted into
phenoxylacetal by heating sodium
phenate with chloracetal at 160^
(Autenrieth, Ber. 24, 162 ; Pomeranz,
Monats. 16, 7^9).

[Chloracetal is prepared by the action
of chlorine on ethfl alcohol (Lieben,
Ann. 104, 114; Fritsch, Ann. 279,
288 : see also 64, p. 1 11).]

Phenoxylacetal when heated with zinc

Digitized by




chloride (in acetic acid solution) con-
denses to coumarone (Stoermer, Ber.
80, 1703), and this can be reduced to
phlorol as below under D.

[D.] From conmarin [Vol. II] through
the chloride or bromide (Perkin, Zeit.
[2] 1, 178; Joum. Ch. Soc. 17, 368;
24, 37; Ann. 167, 116; Fittig and
Ebert, Ann. 216, 163), a-chlor- or a-
bromcoumarin (Perkin, loc, ciL ; also
Joum. Ch. Soc. 23, 368), o-couma-
rilic acid by the action of alcoholic
potash (Ibid. Joum. Ch. Soc 24,
45 ; Fittig and Ebert, loc. cH.),
coumarone by heating coumarilic acid
with lime (Fittig and Ebert, loc, ciL
168 and 226, 347), and reduction of
coumarone in hot alcoholic solution with
sodium, hydrocoumarone being simul-
taneously formed (Alexander, Ber. 26,

The conversion of hydrocoumarone
into o-ethylphenol can also be effected
by boiling with strong hydriodic acid
solution (Baeyer and Scuff ert, Ber. 84,
52). Coumarone also gives o-ethyl-
phenol among the products of its de-
composition by alcoholic alkali (Stoermer
and Kahlert, Ber. 36, 1630).

[E.] From salicylic aldehyde [ll7]
and acelic acid [Vol. II] through o-
aldehydophenoxyacetic acid (aldehydo-
phenylglycollic acid) by the action of
ehloracetic acid on the sodium compound
of the aldehyde (Rossing, Ber. 17, 2990),
coumarone by heating the aldehyde acid
with acetic anhydride and sodium ace-
tate {Ibid. 3Cx;o), and then as under D.

[F.] Cinnamic acid [Vol. II] when
nitrated gives a mixture of o- and p-
nitro-acids (Beilstein and Kuhlberg,
Ann. 163, ia6; Morgan, Ch. News,
86,269; Jahresber. 1877, 788; Miiller,
Ann. 212, 124; Drewsen, Ann. 212,
151 ; Fischer and Kuzel, Ann. 221,
265). The former, by the action of hypo-
chlorous acid on the sodium salt, yields
(with o - nitrophenylchlorlactic acid)
i^-chlor-2-nitrostyrene = o-nitrophenyl-
w-chlorethylene (Lipp, Ber. 17, 1070),
which, by reduction and the diazo-
method, gives I'-^-chlorvinylphenol = o-
hydroxy-a)-chlorstyrene (Komppa, Ber.
26, 2970). The latter when heated
with strong potash solution yields

coumarone {Ibid. 2971), which can be
converted into phlorol as xmder D.

[Q.] Benzoic aldehyde [ll4] on nitra-
tion gives (with much m-nitro-) a small
quantity of o-nitro-aldehyde (Rudolph,
Ber. 18, 310), which, on heating with
acetic anhydride and sodium acetale,

S'elds o-nitrocinnamic acid (Gabriel and
!eyer, Ber. 14, 830). The latter can
be converted into coumarone and phlorol
as under F.

Note: — For o-nitrobenzaldehyde generators
see also under indigo [VoL II].

[H.] From phenylacetic acid [Vol. II]
through the % : 4-dinitro-acid by nitra-
tion (Radziszewski, Ber. 2, 210; Gabriel
and Meyer, Ber. 14, 823), 2-nitro-4-
amino-acid by reduction, the diazo-
chloride by the action of nitrous acid
in presence of hydrochloric acid, o-nitro-
benzaldoxime by heating the diazo-
chloride with alcohol, o-nitrobenzalde-
hyde by oxidising the aldoxime with
chromic acid (Gubriel and Meyer, loc.
cit. and 15, 3057; Gabriel, Ibid, 16,
520), and then as under Q.

[I.] Acetoacetic ester [Vol. II] and
benzene can give rise to phlorol by the
following steps : —

Benzene is brominated, the mono-
brombenzene converted by cold nitration
into brom-2 : 4-dinitrobenzene (Kekul6,
Ann. 137, 167; Spiegelberg, Ann. 197,
257 : see also Walker and Zincke, Ber.
6, 117), the latter combined with
sodio-acetoacetic ester so as to form 2 :
4-dinitrophenylacetoacetic ester (Heck-
mann, Ann. 220, 131 : a bis-dinitro-
phenyl derivative is formed simul-
taneously). The dinitrophenyl ester on
heating in alcohol with 10 per cent
sulphuric acid is converted into 2 : 4-
dinitrophenylacetic acid {Ibid. 134),
which can be treated as above.

[J.] Racemic or tartaric acid [Vol. II]
and n-pi-op'/l alcohol [16] are generators
of ethylbenzene, and therefore of
phlorol, by the following steps: —

Pyroraeemic acid is obtained from the
above acids by dry distillation or other
method (see under benzyl alcohol [64 ;
N]), and this, when mixed withpropionic
aldehyde and barium hydroxide solution,
condenses to 1:3: 5-ethylisophthalic

Digitized by


64 j-ee.]



acid (Doebner, Ber. 23, 1x379 ; 24,
1746), which gives ethylbenzene on
distilling the calcium salt {Ibid. 23^

238 ).

NoTB : — The generators of pjroracemic acid
referred to under benzyl alcohol [54 ; F ; I ;
O ; P] thus become, with n-propyl alcohol,
generators of phloroL



i Acetophenone [7; D and 114; A]
gives dypnone [CH3 . qC^H.) : C :
CH . CO . CgHg] as the first product of
condensation^ and this^ on heating for
80 hours at 280**, yields ethylbenzene
(Ameye, Bull. Acad. Roy. Belg. [3] 87,
227 ; Delacre, Ibid. [3] 39, 68 ; Ch.
Centr. 1900, 2, 256).

Ethylbenzene is also among the pro-
ducts of reduction of acetophenone by
sodium in alcohol (Klages and AUen-
dorff, Ber. 31, 1003).


a-Ethylphenol ; Keta-ethyl-




Natural Source,

A phlorol probably occurs as isobutyr-
ate in oil of arnica root from Arnica
tnontana (Sigel, Ann. 170, 354) which
may be m-ethylphenol, but this requires

Synthetical Processes.

[A.] From ethylbenzene (see imder
phlorol [64; A]) by bromination and
sulphonation, whereby (with the 4-
brom-2-sulphonic acid) there is formed
ethyl-2-brombenzene-3- or 5-sulphonic
acid. The latter on debromination with
zinc dust and ammonia g^ves ethyl-
benzene-m-sulphonic acid (Sempotowski,
Ber. 22, 2673), which yields m-ethyl-
phenol on potash fusion (Ibid. 2674).

Or the ethyl-p-nitrobenzene (obtained
as under phlorol [64 ; A]) can be re-
duced to ethyl-p-aminobenzene, acetyl-
ated, nitrated, and hydrolysed so as to
form 3-nitro-4-aminoethylbenzene, the
amino-group replaced by hydrogen by

the diazo-method, the ethyl-m-nitro-
benzene reduced to ethyl -m-amino-
benzene, and the latter converted into
m-ethylphenol by the diazo- method
(B^hal and Choay, Bull. Soc. [3] 11,

66. Carvacrol; Cymophenol ;

6-Kethylr3-Isoprop7lplLenol ;

1 : 4-Kethylllietho6t]l7^2-P]LenoL



CM3 . Cxi • CU3

Natural Sources.

Occurs in oils of Origanum hirtum
from Trieste and 0. femyrncBum from
Smyrna (Jahns, Arch. Pharm. 216, i ;
Gildemeister, Ibid, 231, 182); in oil
from the pepperwort or summer savory,
Satureia horlemig, and the mountam
savory, 8, montana (Jahns, Ber. 16,
816; Haller, Comp. Rend. 94, 132;
Bull. Soc. [2] 37, 41 1) ; in oil of thyme
from Thymus serpyHum (Jahns^ Arch.
Pharm. 216, 277; Ber. 16, 819); in
oil of wild bergamot from Monardu
Jldulosa (Kremers, Ch. Centr. 1897,
2, 41 ; Pharm. Bund. 13, 207 ; Melzner
and Kremers, Pharm. Rev. 14, 198;
Kremers and Hendricks, Pharm. Arch.
2, 73), and in the oil from Tycnanthemum
laficeolatum = Thymus virginicns (Correll,
Pharm. Rev. 14, 32; Ch. Centr. 1898,

1, 123). . . .

Occurs in small quantity in the
ethereal oil from the fruit of the Mexi-
can Schinus molle (Gildemeister and
Stephan, Arch. Pharm. 236, 582).

According to Duyk carvacrol occurs
with thymol in oil of thyme from T.
vulgaris (Ch. Centr. 1898, 1, 783;
Joum. Pharm. [6] 7, 190). The oil
of Mouarda punctata (from Wisconsin)
probably contains (with thymol) carva-
crol (Kremers and Hendricks, Ch. Centr.
1899, 2, 125; Pharm. Arch. 2, 73).
The oil from the N. American wdd
mint, Mentha canadensis^ may contain
carvacrol (Gage, Pharm. Rev. 16, 412).

Carvacrol is among the phenolic con-

Digitized by




stituents of oil of camphor (Sugiyama ;
Schimmers Ber. Oct 1902 ; Chu Centr.
190a, 2, 1207).

Synthetical Processes.

[A.] From ci/mene [6] by sulphona-
tioQ (Gerhardt and Cahours^ Ann. Chim.
[3] 1, 106; Delalande, Ibid. 368;
Miiller, Ber. 2, 130; Jacobsen^ Ber.
11^ 1060 ; Claus and Cratz^ Ber. 13^
901; 14, 2141; Spica, Ber. 14, 653;
Gazz. 11, 201 ; Sieveking, Ann. 106,
260 ; Beilstein, Ann. 170, 287 ; Patemb,
Ber. 7, 591; Gazz. 3, 544; Kraut,
Ann. 192, 226; Baar, Ann. 220, 18^,
and potash fusion of the a-(2)-suIphomc
acid thus formed (Pott, Ber. 2, 121 ;
H. Miiller, Ibid. 130; Jacobsen, Ber.
U, 1060). Cjrmene on nitration gives
2-nitrocymene (CH3= i) (Barlow, Ann.
98, 245 ; Landoiph, Ber. 6, 937 ;
Fittica, Ann. 172, 314; SchuraofP,
Journ. Russ. Soc. 19, 119; Widman,
Ber. 19, 584 ; Soderbaum and Widman,
Ber. 21, 2126), and 2-aminocymene by
reduction (S5derbaum and Widman,
loc, cit. 2127). The cymidine thus
formed yields carvacrol by the diazo-
method (Semmler, Ber. 25, 3353).

[B.] Carvone [l27] on heating with
acids or alkalis gives carvacrol (Volckel,
Ann. 86, 246; Kekul6 and Fleischer,
Ber. 6, 1088; Lustig, Ber. 19, 12;

Online LibraryRaphael MeldolaThe chemical synthesis of vital products and the interrelations between organic compounds → online text (page 22 of 55)