Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
I~is invention rel.ates -to the use of dialkyl
malonates as or~anic sunscreen adjuvants (PM-l)
Extensive s-tudies have been made of the ultra-
violet radiation of sunlight and skylight reaching the sur-
~ace of the earth and the ef~ects of such radiation on the
human skin. It has been established that the radiation
between 290 n~mometers and 315 nanometers produces sub-
stantially all of the burning, or erythemal energy, and a
substantial portion of the tanning energy, while the between
315 nanometers and 400 nanometers promotes incident tanning~
The cosmetic industry has divided these spectra into respec-
tively W-B, and W-A. The dif~erent intensities and the
erythemal and tanning effectiveness of the various wave
lengths within these ranges have been established and meth
ods have been determined for calculating accurately their
effects on normal untanned skin.
Approximately 76% of the physiological tanning
potential of sunlight is found in the ultraviolet range
between ~90 nanometers and 315 nanometers, the so-called
W-B or erythema area' the balance is ~ound in the range
between 315 nanometers and 400 nanometers, the so-called
W-A tanning area.
Typical organic sunscreenssuch as 2-ethylhexyl
para methoxy cinnamate, homomenthyl salicylate, p-amino-
benzoic acid and its esters, p-dimethyl amino benzoates,
hydroxy and dihydroxy-4-methoxy benzophenones, and ben~al-
phthalides provide protection in the ~rythemal W -B area,
but lesser protection in the tanning areaO
It is becoming increasingly apparent that ultra-
violet in the tanning UV-A area can also have detrimental
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3~
effects on skin health, e.g. causing premature aging as
well as skin cancer. Accordingly, the need has developed
for more effective broad spectrum sunscreens to filter out
~he entire radiation. This need can mean disrupting
established formulation prDcedures, with the usual cosmetic
oil carriers.
Some malonates have been disclosed as UV
absorbers for industrial uses. Typically they are com-
pletely unsuitable for cosmetic purpose in human applications,
e.g~ German Patent No~ 1,087,902. A malonate, diethyl p-
dimethyl-amino-benzalmalonate has been disclosed in U.S.
Patent No. 3,895,10~ as a conventional UV absorber in
a polyamide resin film, but actually provides substantially
no protection, even in the burning range.
It has now been found that particular sub-
stituted dialkyl malonates provide surprising protection in
the tanning area, particularly around 370 nanometers, and
are compatible with and adjuvants for organic sunscreens.
This permits of utilizing established formulation procedures.
The adjuvants of this invention are substituted
dialkyl malonates in which the R alkyl ~roup has from 1 to
5 carbon atoms as illustrated in the following moiety:
H ~ / COOR
-- C = C
COOR
The efficacy of the dialkyl malonates as adju-
vants are determined in a empiric manner. Thus the parti-
~~~cularly preferred compounds are p-methoxy benzal diethyl
malonate, p-methoxy benzal diisobutyl malonate, cinnamal
diethyl malonate, indolal diethyl malollate, fural dietl~
,~ _
~5~3~
~alonate, and 3,4,5-trimethoxy benzal diethyl malonate. The
cinnamal compound is especially effective~
The adjuvants of this invention are prepared
by a typical knoevenagel reaction.
~ COOC2H5
R' - C - H + CH2 benzoic acid piperidine ~
COOC 2H5
H COOC2H5
H 0 + R' - C = C
COOC2H5
R' = aromatic
The solids are crystallized from e.g. isopropanol
and the liquids are fractionately distilled off under vacuum.
The organic sunscreens with which the adjuvants
of this invention are employed are discussed above. A
benzalphthalide may also be used, U.S Patent No. 4,333,920,
particularly 4-pentoxybenzalphthalide.
The overall composition adapted for application
to the human skin thus comprises a cosmetic oil carrier known
to the trade, e.g. mineral, vegetable and animal oils and
isopropyl myristate, with an organic sunscreen, and an ad-
juvant of this invention~ The sunscreen and the adjuvant are
utilized in an amount sufficient to provide the desired pro-
tection for the skin. Typical total amounts of sunscreens
and adjuvants comprise up to about 10 wt. % of the composi-
tion.
This invention, product workup and properties
~-of the composition will be bet-ter understood by re~erence to
the following non-limiting examples~
Example 1
A mixture containing 35,' 2,~-dihydroxy~ ethoxy
~ s~
benzophenone and 65% cinnamal diethyl malonate produced a
total block when used at a concentration of between 5% to
10% in the final composition.
Exa~le 2
Between 5% - 6% of a mixture containing 50%
2-ethylhexyl-p-dimethylamino benzoate and 50% diethyl
cinnamal malonate produced a total block.
Exa~ple 3
Between 5% - 5.5% of a mixture containing 50%
2-ethylhexyl-p-methoxy cinnamate and 50% diethyl cinnamal
malonate produced a total block.
Example 4
Between 4.5% - 5% of a mixture containing 25%
4-pentoxy benzalphthalide and 75% diethyl p-methoxy benzal
malonate produced a total block.
Example 5
Between 5% - 6% of a mixture containing 30%
diisobutyl p-methoxy benzal malonate and 70% 4-pentoxy benzal
phthalide produced a total block.
Example 6
Between 3% - 4% of a mixture containing 50%
p-methoxy benzalphthalide and 50% diethyl fural malonate
produced a total block.
Other formulations according to this invention
provide similar results.
Substituted derivatives of the adjuvants of
this invention can be employed, particularly o~ the cinnamal
diethyl malonate.
~ hese examples demonstrate that the materials
of this inven~ion in even small ~lantities are e~tremely
.~ _
effective adjuvants for organic sunscreens and remedy the
short-comings of the latter.
~ s can be seen, mixtures of the materials of
this invention, and also the organic sunscreens, can be
employed where desired.
The advantages of this invention will be ap-
parent to the skilled in the art. Improved, highly effec-
tive, novel broad spectrum sunscreen compositions are made
available, utilizing a dialkyl malonate.
It will be understood that this invention is
not limited to the specific examples which have been offered
as particular embodiments, and that modifications can be
made without departing from the spirit thereof.
_
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33
SUPPLEMENT~RY DISCLOSURE
As mentioned in the principal disclosure, partic-
ular dialkyl malonates have been found useful as organic
sunscreen adjuvants providing effective protection in the
tanning area, especially around 370 nanometers~ These partic-
ular dialkyl malonates are p~methoxy benzal diethyl malonate,
p-methoxy benzal diisobutyl malonate, cinnamal diethyl
malonate, indolal diethyl malonate, fural diethyl malonate
and 3,4,5 trimethoxy benzal diethyl malonate.
It has now been further found that a substituted
cinnamal diethyl malonate is especially useful in the present
invention. This additional compound is diethyl-~ methyl
cinnamal malonate having the following structural formula:
CH = C - CH = C \
CH3 COOC2~5
Accordingly, a feature of the invention with which
this supplementary disclosure is concerned with resides in
the provision o-f a composition adapted for application to the
~0 human skin, comprising a cosmetic oil carrier containing
distributed therein an effective amount to provide substantial
protection against erythemal and tanning radiation of an organic
sunscreen selected from the group consisting of 2-ethylhexyl
para methoxy cinnamate, homomenthyl salicylate, p-amino benzoic
acid and its esters, p-dimethyl amino benzoates, hydroxy and
dihydroxy-4-methoxy benzophenones, and benzalphthalides, and
as an adjuvant therefor diethyl- ~ -methyl cinnamal malonate.
In another aspect, there is also provided a
method of protecting the human skin from the effects of
erythema and tanning radiation in sunlight, ~hich comprises
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applying to the skin an effective sunscreening amount of an
organic sunscreen as defined above, and as an adjuvant there-
for diethyl- ~ -methyl cinnamal malonate.
The following additional example further
illustrates the invention.
Example 7
Between 5% - 6% of a mixture containing 50% 4-
pentoxybenzalphthalide and 50% diethyl-,~ -methyl cinnamal
malonate produced a total block.
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