Cyclopentyl-cyanomethyl-cyclopentenes, process for their preparation and their use as odoriferous substances

New nitriles which are odoriferous substances having an extremely fresh note are accessible by Knoevenagel condensation of 2-cyclopentyl-cyclopentanone and cyanoacetic acid and decarboxylation of the reaction product.

The invention relates to new compounds of the formula 
##STR1## 
wherein the broken line indicates the three possible positions of a 
C.dbd.C double bond, to a process for the preparation of these compounds 
by Knoevenagel condensation of 2-cyclopentyl-cyclopentanone and 
cyanoacetic acid and decarboxylation of the reaction product, and to the 
use of the new compounds as odoriferous substances. 
The Knoevenagel condensation can be carried out in a manner which is known 
per se (compare, for example, Organikum, 15th edition, VEB Deutscher 
Verlag der Wissenschaften, Berlin, 1984, page 571 et seq.). As a rule 1 to 
3, preferably 1 to 2, mol of cyanoacetic acid are employed per mole of 
2-cyclopentylcyclopentanone. The reaction is carried out in the presence 
of 0.005 to 0.5, preferably 0.05 to 0.3 mol of catalyst per mole of 
2-cyclopentylcylcopentanone, if appropriate in the presence of 0.1 to 1, 
preferably 0.2 to 0.5, mol of glacial acetic acid, possible catalysts 
being, for example, piperidine, .beta.-alanine or ammonium acetate. The 
reaction can thus best be carried out in an organic solvent which forms an 
azeotrope with water. Suitable organic solvents of this type include 
aromatics, such as benzene, toluene and xylene; these are in general 
employed in amounts of 100 to 1,000, preferably 100 to 500, ml per mole of 
2-cyclopentylcyclopentanone. The reaction temperature is best chosen such 
that the primary product formed is decarboxylated immediately; the 
temperature is preferably 100.degree. to 160.degree., in particular 
135.degree. to 145.degree. C. As soon as the formation of water and carbon 
dioxide has ended, the reaction mixture can be worked up. 
The 3 possible isomers are not all formed in the same amount: 
The cyanomethylene a derivative of the formula (II) 
##STR2## 
is formed in a minor amount and its smell is of no interest. The preferred 
cyclopentyl-cyclomethylcyclopentenes according to the invention correspond 
to the formula (III) 
##STR3## 
wherein the broken line indicates the two possible positions of a C.dbd.C 
double bond. 
The two isomers of formulae (IV) and (V) 
##STR4## 
are also not equivalent, as the following descriptions of their smells 
show: 
Compound IV: aldehydic, melon-like green; 
Compound V: watery, extremely potent marine algae note, somewhat fruity, 
like gooseberries or rhubarb. 
The ratio of the isomers formed can be influenced by the reaction 
conditions (compare Examples 1 and 2). Although the absence of glacial 
acetic acid and the use of relatively small amounts of solvent (Example 1) 
gives a higher overall yield, the yield of the desired product (V) is 
lower. 
In the presence of a strong base such as an alkali metal alcoholate (for 
example sodium isopropylate), the less desirable isomer IV is already 
partly isomerised into the desired isomer V at room temperature (compare 
Example 3). 
The compounds (I) according to the invention can be used in combination 
with other odoriferous substances which are known per se (Arctander, 
Perfume and Flavor Chemicals, Montclair, N.J. (USA), 1969) and essential 
oils which are known per se (Arctander, Perfume and Flavor Materials of 
Natural Origin, Elisabeth, N.J. (USA), 1960) and lead to perfume bases and 
odoriferous substance compositions which have highly expressive notes and 
are outstandingly suitable for perfuming finished products in the aerosol, 
detergent and domestic cleaner sector, and also the fine perfumery and 
cosmetics sector, for example for detergents, hair care agents, bath 
additives, dishwashing agents, washing powders, soaps, anti-perspirants, 
powders, creams, shaving lotion, aftershave lotions, air fresheners, WC 
cleaning agents and sunscreen agents. 
The isomeric nitriles of the formula (I) can be employed here individually 
or as a mixture. 
The compounds I according to the invention are in general employed in these 
preparations in an amount of 0.001 to 1% by weight, preferably 0.01 to 
0.1% by weight, based on the finished perfume oil. 
The perfume compositions and perfumed products can be prepared in the 
customary manner, for example by bringing the components together. 
The percentage data in the following examples denote percentages by weight.

EXAMPLES 
Example 1 
304 g (2 mol) of 2-cyclopentylcyclopentanone, 205 g (2.4 mol) of 
cyanoacetic acid and 40 g (0.45 mol) of ammonium acetate in 300 g of 
xylene are heated under reflux, using a water separator, in a three-necked 
flask fitted with a stirrer, water separator and gas meter. After 6 hours, 
67 g of an aqueous phase and about 60 l of CO.sub.2 have been split off. 
The reaction mixture is washed successively with 100 g of 10% strength 
sulphuric acid, with 200 g of 5% strength sodium hydroxide solution and 
with water and is distilled over a 30 cm packed column. In addition to 80 
g of 2-cyclopentyl-cyclopentanone (T(bottom)=130.degree. C.; 
(T(head)=85.degree. C.; 0.6 mbar), 180 g of the nitriles of the formula 
(I) according to the invention (T(bottom)=175.degree. C.; 
T(head)=100.degree. C.; 0.6 mbar) are obtained. A yield of 70%, based on 
the ketone reacted, is calculated. 
Composition of the resulting nitriles according to the gas chromatogram 
(column: 60M DB1; temperature condition: 80-4-250.degree. C; that is to 
say: gas chromatogram temperature-programmed, initial temperature: 
80.degree. C., no isothermal first runnings; heating-up rate: 4.degree. C. 
per minute; final temperature: 250.degree. C.). 
73.5% of 1-cyanomethyl-5-cyclopentyl-cyclopent-1-ene; see NMR spectrum, 
FIG. 1. 
21.2% of 1-cyanomethyl-2-cyclopentyl-cyclopent-1-ene; see NMR spectrum, 
FIG. 2. 
3.7% of 2-cyanomethylene-dicyclopentyl. 
Example 2 
382 g (4.5 mol) of cyanoacetic acid, 456 g (3.0 mol) of 
2-cyclopentylcyclopentanone, 23 g of ammonium acetate (0.3 mol) and 72 g 
(1.2 mol) of acetic acid in 900 ml of xylene are heated under reflux, 
using a water separator, in the apparatus described in Example 1. After 12 
hours, 101 l of CO.sub.2 and 74 g of an aqueous phase have been split off. 
The reaction mixture is washed successively with 200 ml of 10% strength 
sulphuric acid, with 400 ml of 5% strength sodium hydroxide solution and 
with water and is distilled over a 30 cm packed column. In addition to 158 
g of 2-cyclopentylcyclopentanone (T(bottom)=130.degree. C.; 
(T(head)=85.degree. C.; 0.6 mbar), 205 g of the nitriles of the formula 
(I) according to the invention (T(bottom)=175.degree. C.; 
T(head)=100.degree. C.; 0.6 mbar) are obtained. A yield of 60%, based on 
the ketone reacted, is calculated. 
Composition of the resulting nitriles according to gas chromatogram 
(column: 60 DB 1; temperature condition: 80-4-250.degree. C.): 
34.1% of 1-cyanomethyl-5-cyclopentyl-cyclopent-1-ene; 
62.9% of 1-cyanomethyl-2-cyclopentyl-cyclopent-1-ene; 
3.0% of 2-cyanomethylene-dicyclopentyl. 
Example 3 
0.5 g (0.021 mol) of sodium is dissolved in 100 g of anhydrous isopropanol, 
while heating, in a three-necked flask fitted with a dropping funnel, 
reflux condenser and nitrogen inlet. The homogenous solution is cooled to 
room temperature, 100 g (0.57 mol) of a mixture of the nitriles of the 
formula (I) according to the invention (containing 62.8% of 
1-cyanomethyl-5-cyclopentyl-cyclopent-1-ene; 34.0% of 
1-cyanomethyl-2-cyclopentyl-cyclopent-1-ene; and 3.2% of 
2-cyanomethylene-dicyclopentyl) are added and the mixture is subsequently 
stirred at room temperature for 4 hours. It is then neutralised to pH=6 
with glacial acetic acid and distilled. 
85.0 g of distillate of the nitriles of the formula (I) are obtained; for 
the composition, see below. A yield of 85%, based on the nitrile mixture 
employed, is calculated. The amount of residue is 13 g. 
Composition of the distillate according to gas chromatogram (column: 60 m 
DB 1; temperature condition: 80-4-250.degree. C.): 
8.8% of 1-cyanomethyl-5-cyclopentyl-cyclopent-1-ene; 
66.0% of 1-cyanomethyl-2-cyclopentyl-cyclopent-1-ene; 
25.2% of 2-cyanomethylene-dicyclopentyl. 
The trivial names used in the following use examples have the following 
meaning: 
Iraldein gamma pure 
##STR5## 
3-Methyl-4-(2,6,6-trimethylcyclohex-2-en-1-yl)-but-3-ene-2-one 
Eugenol 
##STR6## 
2-Methoxy-4-allylphenol 
Musk ketone 
##STR7## 
2,6-Dimethyl-3,5-dinitro-4-tert.-butylacetophenone 
Vertocitral: Mixture of 
##STR8## 
Evernyl 
##STR9## 
Methyl 2,5-dimethyl-4,6-dihydroxy-benzoate 
Use 1 
A perfume composition is prepared by mixing the following constituents 
(amounts stated in grams): 
______________________________________ 
Aldehyde C10 (decanal) 5.0 
Nitriles of the formula (I), 1% strength in 
40.0 
dipropylene glycol (0.04% strength in perfume oil) 
Galbanum resin 20.0 
Dist. bergamot oil 60.0 
Dihydromyrcenol 50.0 
Dihydromyrcenyl acetate 40.0 
Citrylal (H + R) 20.0 
French petit grain oil 40.0 
Muguet lily of the valley base # 10689F (H + R) 
60.0 
Pure phenylethyl alcohol 60.0 
Citronellol supra 50.0 
Benzyl acetate 50.0 
Alpha-hexylcinnamaldehyde 60.0 
cis-3-hexenyl salicylate 100.0 
Benzyl salicylate 80.0 
Iraldein gamma pure 80.0 
Eugenol 10.0 
Mousse C abs. verte jug. 50% in TEC 
10.0 
Musk ketone 80.0 
Dipropylene glycol 85.0 
1,000.0 
______________________________________ 
TEC = Triethyl citrate? 
The nitriles of the formula (I) employed are distinguished by the fact that 
even when a very small amount is added to a suitable perfume oil, the 
latter is caused to vary impressively in the direction of "marine 
freshness". 
Use 2 
A performed composition is prepared by mixing the following constituents 
(amounts stated in grams): 
______________________________________ 
2-Methyldodecanal 1.0 
Nitriles of the formula (I), 1% strength in 
2.0 
dipropylene glycol (0.02% strength in perfume oil) 
Vertocitral (H + R) 0.5 
Dihydromyrcenol 5.0 
Terpinyl acetate 30.0 
Citrylal (H + R) 4.0 
Brazilian orange oil 6.0 
Spanish lavender oil 6.0 
Eucalyptus globulus oil, 80/85% pure 
3.0 
Moroccan armoise oil 1.0 
Isobornyl acetate 3.0 
Pure phenylethyl alcohol 3.0 
Geraniol 6.0 
Benzyl acetate 4.0 
Alpha-hexylcinnamaldehyde 3.0 
Decolorised clove leaf oil 1.0 
Coumarin 3.0 
Florida cedar wood oil 6.0 
Evernyl (RBD) 0.5 
Mousse A concr. 50% in TEC 1.0 
Musk ketone 2.0 
10% strength indole in dipropylene glycol 
1.0 
Dipropylene glycol 8.0 
100.0 
______________________________________ 
The top note is given a clean freshness by addition of the nitriles of the 
formula (I) employed. The nitriles of the formula (I) have a very potent, 
fresh marine fragrance which, in dilution is reminiscent of algae, fresh 
fish and the coast. Herbal spicy notes of oak moss, dill and cumin are 
also evident.