JPH0135832B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel derivatives of alkylidene norbornanone, such as 5-ethylidene-2 or 3-norbornanone, and a process for their preparation.

Conventionally, compounds with norbornane rings are
Various types of acetal compounds have been produced, but the present inventors obtained a new acetal compound by reacting alkylidene norbornanone with a diol, and this acetal compound has an aroma and can be used as a flavoring component of fragrances. The present invention has been completed based on the discovery that it is useful as an organic compound, and that it can also be effectively used as an intermediate in organic synthesis and as a raw material for synthetic resins by utilizing the unsaturated groups such as alkylidene groups it has. .

That is, the present invention relates to an alkylidene norbornanone acetal represented by the following general formula (), (Here, R ₁ is an alkylidene group having 2 to 3 carbon atoms, and R ₂ is a saturated hydrocarbon residue having 2 to 7 carbon atoms.) The invention below relates to a method for producing an alkylidene norbornanone acetal represented by the above formula (), which is characterized by carrying out the reaction at 10 to 150°C.

The alkylidene norbornanone used in the production method of the present invention is represented by the following formula ().

Here, R ₁ is an alkylidene group having 2 to 3 carbon atoms,
That is, ethylidene group, propylidene group, isopropylidene group, etc.

For example, when R ₁ is an ethylidene group,
The above formula () is represented by the following formula () or ().

In the production method of the present invention, the above-mentioned alkylidene norbornanone may be used alone or in a mixture of two or more.

The above-mentioned alkylidene norbornanone can be obtained by adding sulfuric acid, formic acid or acetic acid to alkylidene norbornene, for example, ethylidene norbornene, and then hydrolyzing it, or by hydroboration-hydrogen peroxide oxidation of ethylidene norbornene. , ethylidenenorbornanol, and then oxidizing the alcohol. However, in addition to ethylidenenorbornanol, the above-mentioned method that involves addition of organic acids produces a large amount of tricyclene compounds, which are less useful as fragrances, and these compounds cannot be separated by normal distillation. Since it is difficult, it is better to obtain ethylidene norbornanol using hydroboration.

In addition, the above ethylidenenorbornene (5-ethylidene-bicyclo[2,2,1]hept-2-ene) is produced by EP by the Ziels-Alder reaction and isomerization reaction between cyclopentadiene and butadiene.
It is easily and inexpensively produced industrially as a third copolymer component of rubber.

In the production method of the present invention, the diols to acetalize the alkylidenenorbornanone are 1,2-diol and 1,3-diol.

Here, 1,2-diol is a compound in which two hydroxyl groups are substituted on adjacent carbon atoms of a saturated hydrocarbon, and 1,3-diol is a compound in which two hydroxyl groups are substituted into one carbon atom of a saturated hydrocarbon. Each refers to a compound in which two carbon atoms are substituted on sandwiching carbon atoms.

Typical examples of the above 1,2-diols are ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,2-,2,
3- or 3,4-hexanediol, 1,2-
or 2,3-pentanediol, 1,2-cyclohexanediol and 1,2-methylcyclohexanediol.

In addition, as 1,3-diol, 1,3-propanediol, 1,3-butanediol, 2,2
-dimethyl-1,3-propanediol, 2,2
-diethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-
These include 1,3-propanediol, 1,3-cyclohexanediol, and 1,3-methylcyclohexanediol.

In the acetalization in the production method of the present invention,
The above diols can be used alone or in mixtures.

When the above diol is expressed as HO--R ₂ ---OH, the manufacturing method of the present invention consists of the following steps.

That is, The reaction (1) above is carried out in the presence of an acidic catalyst, but since the unsaturated hydrocarbon group R must not be changed, it is dangerous to operate at high temperatures using a large amount of a strong acid catalyst. It is necessary to choose conditions that will prevent polymerization reactions from occurring.

Acidic catalysts include sulfuric acid, hydrochloric acid, hydrobromic acid, hydrofluoric acid, fluorosulfonic acid, chlorosulfonic acid, methanesulfonic acid, toluenesulfonic acid, naphthalenesulfonic acid, boron fluoride hydrate, phosphoric acid, Polyphosphoric acid, trichloroacetic acid, trifluoroacetic acid, perfluoro fatty acid, strongly acidic ion exchange resin, phosphoric anhydride, boric anhydride, acid clay, etc. are used alone or in a mixture of two or more,
Application of boron fluoride, aluminum chloride, iron chloride, anhydrous sulfuric acid, super strong acids, etc., which cause side reactions, to an anhydrous reaction system should be avoided. Said
In order to achieve the reaction (1), the reaction temperature must be 10~
It is carried out at 150°C, particularly preferably from 30 to 100°C. When the reaction temperature is below 10°C, it is necessary to use a large amount of acidic catalyst and carry out the reaction for a long time, which may cause side reactions other than acetalization, such as producing a large amount of polymer and inhibiting the desired product. yield decreases. Moreover, when the reaction temperature is set to 150° C. or higher, addition of the acidic catalyst to the unsaturated hydrocarbon group R occurs, which also reduces the yield of the target product.

In addition, although the reaction (1) above is acetalization,
It is necessary to allow the acetalization reaction to proceed by removing water produced as a by-product during the acetalization reaction.

Therefore, it is preferable to carry out the acetalization reaction under reflux using a solvent that can form an azeotrope with water and is inert to the acetalization reaction, such as benzene or toluene. Further, during acetalization, it is preferable to use a solvent in order not to change unsaturated bonds.

In the production method of the present invention, the molar ratio of norbornanone derivative and diol to be subjected to the acetalization reaction is 1:0.5 to 1:3, preferably 1:1 to
The ratio is 1:2.

The amount of the acidic catalyst used in the acetalization reaction is 0.01 to 10% by weight, preferably 0.5 to 5% by weight, based on the raw materials in the reaction system.

In reaction (1) above, when a normal alkanol (monoalcohol) is used, it is easy to separate the acetal from the reaction product, but when a diol as shown in the present invention is used, the target product It is necessary to devise ways to obtain the information. The steps leading to the acquisition of the target product are shown in (2) and (3) above, but first, under conditions as mild as possible than the reaction mixture obtained in (1) above,
First, the oily product (2) above, which is the crude product, is separated. For this purpose, the reaction mixture may be poured into water and extracted with an organic solvent, or salted out.
Solvents that do not sufficiently dissolve the reaction mixture (e.g. water,
(ethylene glycol, freon, etc.) is added to the reaction mixture and first separated by a gradient method, liquid separation method, centrifugation method, or the like. During this separation, if non-oily substances such as crystalline substances, rubber-like substances, or resinous substances are mixed in, remove them as much as possible, and also remove non-oily substances such as water and water-soluble organic solvents as much as possible. It is preferable to remove it by drying, evaporation, concentration, adsorption, etc. The oil thus obtained is purified by distillation as shown in (3) above. Regarding this purification method, using other methods other than distillation does not improve the quality of the target product and also reduces the yield. Therefore, for this purification, it is necessary to select a raw material diol that can be carried out by atmospheric distillation, reduced pressure distillation, molecular distillation, etc. If the molecular weight of the diol is large, the target product may solidify or become waxy. If distillation purification is not possible, impurities cannot be separated, so sufficient care must be taken with raw materials. This distillation purification is often carried out by vacuum fractional distillation (vacuum rectification), and if it is sufficiently purified as a result, the alkenyl norbornanone acetal of the present invention can be obtained as a colorless and transparent fluid liquid. be.

The alkylidenenorbornanone acetal of the present invention obtained as described above is represented by the above formula (), and by acetalization, 1,3-dioxolane ring is formed in 1,2-diol, and 1,3-dioxolane ring is formed in 1,2-diol, and 1 ,3-dioxane ring is formed.

That is, in the acetalization of 5-ethylidene-2 or 3-norbornanone and ethylene glycol, ethylidene norbornanone ethylene acetal, that is, spiro[1,3-dioxolane-2,2' or 2,3'-
(5′-ethylidenenorbornane)] is obtained.

or The alkylidene norbornanone acetal of the present invention has a good aroma and is therefore useful in perfume compositions.Furthermore, the unsaturated groups such as ethylidene groups can be used in synthetic reactions, making it useful in the synthetic chemical industry. It becomes an intermediate or a raw material for synthetic resin.

In addition, ethylidene norbornene is as mentioned above.
Since it can be obtained inexpensively and in large quantities as the third copolymerization monomer component of EP rubber, if the ethylidene norbornene obtained by oxidizing this ethylidene norbornene using hydroboration is used as the starting material, the present invention can be carried out. The compound is economically advantageous, and since it does not contain tricyclene compounds, its usefulness as a fragrance is further enhanced.

The norbornene-based compound of the present invention has a woody scent as its base, but it also has not only a noonday note, but also a floral note, a fusea note, and a woody scent.
Moss note, chypre note, leather note, tobacco note, animal note, citrus note,
It can be conveniently blended with resinous notes, green notes, fruit notes, aldehyde notes, ester notes, etc., resulting in various excellent fragrance compositions. In addition to being used as a flavoring agent for various perfumes, cosmetics, soaps, daily necessities, etc., this perfume composition can be widely used as a flavor component, a synthetic essential oil component, a deodorant component, a perfume diluent, and the like.

Next, the present invention will be explained in detail with reference to Examples.

Production Example 5 - Synthesis of ethylidene-2 and 3-norbornanone 36.0 g of 5-ethylidene-2-norbornene
(0.300 mol) in 250 ml of dry tetrahydrofuran, then 5.0 g of sodium borohydride.
(0.129 mol) was added. Boron trifluoride ether complex salt 14.0 ml (0.111 mol) was added while cooling the mixture on ice.
was added dropwise over a period of approximately 30 minutes. 10-20 minutes after completion of dripping
The mixture was stirred at ℃ for about 2 hours. While cooling the reaction mixture on ice, add 25.2 ml of water, then 34.1 ml of 3N sodium hydroxide solution, and then add 30% hydrogen peroxide solution.
34.1 ml was gradually added dropwise. After stirring the reaction mixture at about 50°C for 2 hours, a benzene-ether mixture was added.
The mixture was poured into 100 ml of water, washed several times with a small amount of saturated brine, and the organic layer was dried over anhydrous magnesium sulfate.
After distilling off the solvent, the residue was distilled under reduced pressure to obtain 24.8 g of colorless 5-ethylidene-2 or 3-norbornanol (yield, 60%; bp, 60-61°C/0.45
mmHg) was obtained.

Analysis results ir (neat method): ~3300cm ^-1 (O-H stretching vibration), ~1680cm ^-1 (C=C stretching vibration of ethylidene group), 1060 - 1080cm ^-1 (C=O stretching vibration of alcohol) .

nmr (CDCl ₃ ): 4.5~5.0τ (multiplet, 1H), 6.0~6.3τ (multiplet, 1H), 6.7τ (singlet, 1H), 7.2τ (wide singlet, 1H), 7.5~ 7.7τ (multiplet, 1H), 8.4τ (singlet, 3H), 7.9~8.9τ (multiplet, 6H).

C-2 (carbon atom at the 2nd position) of the main isomer
¹³ C _onr (CDCl ₃ ): ppm (peak intensity) 74.2 (79.4), 73.1 (8.20) Elemental analysis (as C ₉ H ₁₄ O): C (%) H (%) Calculated value 78.3 10.1 Actual value 77.6 10.5 Substitution ^{The 13} C _onr spectrum of the α-carbon (C-2 or C-3) of the hydroxyl group of 2-norbornanol is
Since it is characterized by a resonance peak in the region of 75.0 to 65.0 ppm, each spectrum was assigned to an isomer based on the resonance spectrum in this region, taking into account the change in chemical shift.

In other words, in the case of the ethylidene group-substituted product, unlike the vinyl group, almost no influence of the γ-effect is observed,
Due to the electronic effect of the carbon-carbon double bond, the spectrum of carbon atoms near the bond shifts to a lower magnetic field, so the peak at 74.2 ppm is 6-ethylidene-2.
- norbornanol, and the peak at 73.1 ppm was assigned to 5-ethylidene-2-norbornanol.

In addition, from gas chromatography analysis, ¹³ C _onr was measured for the preparative sample, and it was identified by comparing it with the above characteristic spectrum that 95% of the alcohol content obtained was an exo form, and 5-ethylidene- 2-norbornanol is
It was 65%. Further, no tricyclene compound was contained at all.

After dissolving 5.0 g (0.036 mol) of 5-ethylidene-2 and 3-norbornanol and 19.6 g (0.181 mol) of parabenzoquinone obtained above in 160 ml of dry toluene, 3.7 g of aluminum triisopropoxide ( 0.018 mol) was added gradually. After heating the reaction mixture to reflux for 1 hour,
Add 100ml of potassium sodium tartrate saturated solution;
Extracted with a benzene-ether mixture. The extract was washed with a saturated sodium bicarbonate solution and twice with water, and then dried over anhydrous magnesium sulfate.
By vacuum distillation, 5-ethylidene-2 and 3-
Norbornanone 4.2 g (yield, 85%; bp, 59-61
°C/1.8mmHg).

Analysis results ir (neat method): 1760 cm ^-1 (>C=O stretching vibration), ~1685 cm ^-1 (C=O stretching vibration of ethylidene group), O-H stretching vibration (~3400 cm ^-1 ) is due to oxidation Disappeared due to

nmr ( _CDCl3 ): 4.4-4.7τ (multiplet, 0.6H), 8.0-8.4τ (multiplet, 8H), 8.8-9.2τ (quadruplet, 3H).

n _D ¹⁵ : 1.4804 Elemental analysis (as C ₉ H ₁₂ O) C (%) H (%) Calculated value 79.41 8.82 Actual value 79.05 8.60 Furthermore, gas chromatographic analysis revealed that 5-ethylidene-2-norbornanone was the main component. It was also found that 95% of the cells were exo-bodies.

Example 1 5-ethylidenenorbornanone ethylene acetal {spiro-[1,3-dioxolane-2,
Synthesis of 2' and 2,3'-(5'-ethylidenenorbornane)] 5-ethylidenenorbornanone obtained in the production example
2.5g (0.018mol), ethylene glycol 1.4g
(0.022 mol) and a small amount of para-toluenesulfonic acid were added to 100 ml of benzene, and the resulting water was removed as an azeotrope with benzene while heating under reflux.
After about 1 hour, a saturated sodium bicarbonate solution was added to the reaction mixture, and the mixture was extracted with a benzene-ether mixture. The extract was washed twice with water, dried over anhydrous sodium sulfate, and then distilled under reduced pressure to obtain the 5-
Ethylidene norbornanone ethylene acetal
2.1g (yield, 63.5%; bp, 61-62℃/0.30mm
Hg) was obtained.

Analysis results ir (neat method): ~1690 cm ^-1 (C=C stretching vibration of ethylidene group), C=O stretching vibration (~1750 cm ^-1 ) disappeared by acetalization.

nmr (CDCl ₃ ): 4.6~5.0τ (multiplet, 1H), 6.2τ (singlet, 4H), 7.5τ (broad singlet, 1H), 7.6~7.8τ (multiplet, 1H), 8.4τ ( Singlet, 3H), 7.9-9.0τ (multiplet, 6H).

Elemental analysis (as C ₁₁ H ₁₆ O ₂ ) C (%) H (%) Calculated value 73.3 8.9 Actual value 73.8 8.7 Example 2 Spiro[4,5-dimethyl-1,3-dioxolane-2,2' and 2 , 3'-(5'-ethylidenenorbornane)] The ketones (5-ethylidene-2 and 3-norbornanone) obtained in the production example were acetalized with 2,3-butanediol in the same manner as in Example 1 to obtain the title compound. was obtained in a yield of 70.0%.

Analysis result bp: 68-70℃/0.6mmHg n _D ²³ : 1.4692 ir (neat method): 1640cm ^-1 (stretching vibration of C=C of ethylidene group), and stretching vibration of C=O (1730cm ^-1 ) It disappeared due to acetalization.

nmr (CDCl ₃ ): 4.6~5.1τ (multiplet, 1H), 6.0~6.1τ (quartet, 2H), 7.4~8.7τ (multiplet, 8H), 8.4τ (singlet, 3H), 8.8 ~9.0τ (double line, 6H).

Elemental analysis (as C ₁₃ H ₂₀ O ₂ ) C (%) H (%) Calculated value 75.0 9.6 Actual value 74.5 9.8 Example 3 Spiro [1,3-dioxane-2,2' and 2,3'-(5 '-ethylidenenorbornane)] The ketones (5-ethylidene-2 and 3-norbornanone) obtained in the production example were acetalized with trimethylene glycol in the same manner as in Example 1, yield 80%.
The title compound was obtained.

Analysis result bp: 72℃/0.40mmHg n _D ²⁴ : 1.4831 ir (neat method): 1640cm ^-1 (stretching vibration of C=C of ethylidene group), and stretching vibration of C=O (1730cm ^-1 ) is acetalization Disappeared due to

nmr ( _CDCl3 ): 4.5-5.0τ (multiplet, 1H), 6.1-6.2τ (triplet, 4H), 8.4τ (singlet, 3H), 7.2-8.8τ (multiplet, 10H).

Elemental analysis (as C ₁₂ H ₁₈ O ₂ ) C (%) H (%) Calculated value 74.2 9.3 Actual value 73.8 9.5 Example 4 Spiro[5,5-dimethyl-1,3-dioxane-2,2' and 2 , 3'-(5'-ethylidenenorbornane)]
By acetalizing with 1,3-propanediol in the same manner as in Example 1, the title compound was obtained in a yield of 65.5%.

Analysis result bp: 108-109℃/3.0mmHg n _D ²⁴ : 1.4755 ir (neat method): 1635cm ^-1 (Stretching vibration of C=C of ethylidene group), and stretching vibration of C=O (1730cm ^-1 ) disappears by acetalization.

nmr (CDCl ₃ ): 4.5~5.1τ (multiplet, 1H), 6.1τ (singlet, 4H), 8.3τ (singlet, 3H), 7.3~8.7τ (multiplet, 8H), 9.0τ (singlet) line, 6H).

Elemental analysis (as C ₁₄ H ₂₂ O ₂ ) C (%) H (%) Calculated value 75.7 9.9 Actual value 75.8 10.0 Example 5 Spiro[4-methyl-1,3-dioxane-
Synthesis of 2,2' and 2,3'-(5'-ethylidenenorbornane)] The ketone obtained in the production example (5-ethylidene-2 and 3-norbornanone) was mixed with 1,3-butanediol in the same manner as in Example 1. Acetalized to 70% yield
The title compound was obtained.

Analysis result bp: 82-83℃/0.65mmHg n _D ²⁴ : 1.4898 ir (neat method): 1635cm ^-1 (stretching vibration of C=C of ethylidene group), and stretching vibration of C=O (1730cm ^-1 ) Disappears by acetalization.

nmr (CDCl ₃ ): 4.6~5.0τ (multiplet, 1H), 6.1~6.3τ (multiplet, 3H), 8.5τ (singlet, 3H), 7.3~8.8τ (multiplet, 10H), 8.9τ (double line, 3H).

Elemental analysis (as C ₁₃ H ₂₀ O ₂ ) C (%) H (%) Calculated value 75.0 9.6 Actual value 74.7 9.8 Example 6 Spiro[5,5-diethyl-1,3-dioxane-2,2' and 2 ,3'-(5'-ethylidenenorbornane)]
Acetalization was performed using 3-propanediol in the same manner as in Example 1 to obtain the title compound in a yield of 68%.

Analysis result bp: 75-77℃/0.20mmHg n _D ²⁴ : 1.4835 ir (neat method): 1640cm ^-1 (stretching vibration of C=C of ethylidene group), and stretching vibration of C=O (1730cm ^-1 ) Disappears by acetalization.

nmr (CDCl ₃ ): 4.5~5.0τ (multiplet, 1H), 6.1τ (singlet, 4H), 8.4τ (singlet, 3H), 7.3~8.9τ (multiplet, 12H), 8.9~9.1τ (Triple line, 6H).

Elemental analysis (as C ₁₆ H ₂₆ O ₂ ) C (%) H (%) Calculated value 76.8 10.4 Actual value 76.2 10.1 Example 7 Spiro [4,5-tetramethylene-1,3-dioxolane-2,2' and Synthesis of 2,3'-(5'-ethylidenenorbornane)] The ketone (5-ethylidene-2 and 3-norbornanone) obtained in the production example was acetalized with 1,2-cyclohexanediol in the same manner as in Example 1, and the title The compound was obtained with a yield of 60.5%.

Analysis result bp: 92-94℃/0.35mmHg n _D ²⁴ : 14950 ir (neat method): 1635cm ^-1 (stretching vibration of C=C of ethylidene group), and stretching vibration of C=O (1730cm ^-1 ) Disappears by acetalization.

nmr ( _CDCl3 ): 4.6-5.0τ (multiplet, 1H), 5.9-6.0τ (triplet, 2H), 8.3τ (singlete, 3H), 7.3-8.9τ (multiplet, 16H).

Elemental analysis (as C ₁₅ H ₂₂ O ₂ ) C (%) H (%) Calculated value 76.9 9.4 Actual value 77.1 9.2 Example 8 Spiro[1,3-dioxolane-2,2' and 2,3'-(5 Synthesis of 5-isopropylidene-2-norbornene (which was synthesized from cyclopentadiene and isoprene by a conventional method) in the same manner as in Production Example 1.
5-isopropylidene-2- and 3-norbornanol were obtained, which were oxidized to ketones, and then acetalized with ethylene glycol in the same manner as in Example 1 to obtain the title compound in a yield of 60%.

Analysis result bp: 65-67℃/0.60mmHg n _D ²⁴ : 1.4820 ir (neat method): 1665cm ^-1 (weak absorption, C=C stretching vibration of isopropylidene group) Also C=O stretching vibration (1730cm ^{- 1} ) disappears due to acetalization.

nmr (CDCl ₃ ): 6.1τ (singlet, 4H), 7.4τ (broad singlet, 1H), 8.3τ (singlet, 3H), 8.4τ (singlet, 3H), 7.9~8.8τ (multiplet , 7H).

Elemental analysis (as C ₁₂ H ₁₈ O ₂ ) C (%) H (%) Calculated value 74.2 9.3 Actual value 73.5 9.5

Claims (1)

[Claims] 1 The following formula () [In the formula, R ₁ is an alkylidene group having 2 to 3 carbon atoms, and R ₂ is a saturated hydrocarbon residue having 2 to 7 carbon atoms.] An alkylidene norbornanone acetal represented by the following formula. 2 Alkylidene norbornanone acetal is the following formula () or () [In the formula, _R2 is a saturated hydrocarbon residue having 2 to 7 carbon atoms.] The alkylidene norbornanone acetal according to claim 1, which is represented by the following formula. 3 The compound represented by the above formula () or () is spiro[1,3-dioxolane-2,
2' or 2,3'-(5-ethylidenenorbornane)] according to claim 2. 4 A patent in which the compound represented by the above formula () or () is spiro[4,5-dimethyl-1,3-dioxolane-2,2' or 2,3'-(5'-ethylidenenorbornane)] Claim 2
Alkylidenenorbornanone acetal as described in Section. 5. Claim 2, wherein the compound represented by the formula () or () is spiro[1,3-dioxane-2,2' or 2,3'-(5'ethylidenenorbornane)] alkylidene norbornanone acetal. 6 A patent claim in which the compound represented by the formula () or () is spiro[5,5-dimethyl-1,3-dioxane-2,2' or 2,3'-(5-ethylidenenorbornane)] The alkylidene norbornanone acetal according to item 2. 7 Claims in which the compound represented by the formula () or () is spiro[4-methyl-1,3-dioxane-2,2' or 2,3'-(5-ethylidenenorbornane)] The alkylidene norbornanone acetal according to item 2. 8 A patent claim in which the compound represented by the formula () or () is spiro[5,5-diethyl-1,3-dioxane-2,2' or 2,3'-(5-ethylidenenorbornane)] The alkylidene norbornanone acetal according to item 2. 9 The compound represented by the above formula () or () is spiro[4,5-tetramethylene-1,
3-dioxolane-2,2' or 2,3'-(5'-
ethylidenenorbornane)] according to claim 2. 10 The following formula () consisting of reacting an alkylidenenorbornanone and a diol at 10 to 150°C in the presence of an acidic catalyst [In the formula, R ₁ is an alkylidene group having 2 to 3 carbon atoms, and R ₂ is a saturated hydrocarbon acid group having 2 to 7 carbon atoms.] A method for producing an alkylidene norbornanone acetal represented by the following formula. 11 Alkylidenenorbornanone has the following formula () or () A method for producing an alkylidene norbornanone acetal according to claim 10. 12 Diol is ethylene glycol, 2,3-
Butanediol, trimethylene glycol, 2,
2-dimethyl-1,3-propanediol, 1,
3-butanediol, 2,2-diethyl-1,3
12. The method for producing an alkylidene norbornanone acetal according to claim 10 or 11, wherein the alkylidene norbornanone acetal is one or a mixture of two or more selected from the group consisting of -propanediol and 1,2-cyclohexanediol.