The present invention relates to an acetal compound of the following general formula (1) and an acetal compound of the following general formula (2). The present invention relates to processes for preparing the acetal compound (2), comprising subjecting the acetal compound (1) to a hydrogenation reaction to form the acetal compound (2). The present invention provides a process for preparing 2,3,4,4-tetramethylcyclopentanecarbaldehyde of the following formula (3), comprising subjecting the acetal compound (2) to a hydrolysis reaction to form 2,3,4,4-tetramethylcyclopentanecarbaldehyde (3).

##STR00001##

The present invention relates to an acetal compound of the following general formula (1) and an acetal compound of the following general formula (2). The present invention relates to processes for preparing the acetal compound (2), comprising subjecting the acetal compound (1) to a hydrogenation reaction to form the acetal compound (2). The present invention provides a process for preparing 2,3,4,4-tetramethylcyclopentanecarbaldehyde of the following formula (3), comprising subjecting the acetal compound (2) to a hydrolysis reaction to form 2,3,4,4-tetramethylcyclopentanecarbaldehyde (3).

##STR00001##

The present invention relates to new odorous acetals which are useful as fragrance or flavor materials in particular in providing vanilla and spicy notes with a natural impression resembling vanilla absolute.

The present invention relates to new odorous acetals which are useful as fragrance or flavor materials in particular in providing vanilla and spicy notes with a natural impression resembling vanilla absolute.

The present invention relates to new odorous acetals which are useful as fragrance or flavor materials in particular in providing vanilla and spicy notes with a natural impression resembling vanilla absolute.

The present invention relates to an acetal compound of the following general formula (1) and an acetal compound of the following general formula (2). The present invention relates to processes for preparing the acetal compound (2), comprising subjecting the acetal compound (1) to a hydrogenation reaction to form the acetal compound (2). The present invention provides a process for preparing 2,3,4,4-tetramethylcyclopentanecarbaldehyde of the following formula (3), comprising subjecting the acetal compound (2) to a hydrolysis reaction to form 2,3,4,4-tetramethylcyclopentanecarbaldehyde (3). ##STR00001##

The present invention relates to an acetal compound of the following general formula (1) and an acetal compound of the following general formula (2). The present invention relates to processes for preparing the acetal compound (2), comprising subjecting the acetal compound (1) to a hydrogenation reaction to form the acetal compound (2). The present invention provides a process for preparing 2,3,4,4-tetramethylcyclopentanecarbaldehyde of the following formula (3), comprising subjecting the acetal compound (2) to a hydrolysis reaction to form 2,3,4,4-tetramethylcyclopentanecarbaldehyde (3). ##STR00001##

The present invention relates to a process for preparing a (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound of the following general formula (3-Z): wherein Y represents a halogen atom, Ar represents, independently of each other, an aryl group, and R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, or R.sup.1 and R.sup.2 may form together a divalent hydrocarbon group, R.sup.1-R.sup.2, having 2 to 10 carbon atoms, the process comprising: subjecting a (7Z)-11-halo-1,1-dialkoxy-7-undecene compound of the following general formula (1-Z): wherein X.sup.1 represents a halogen atom, and R.sup.1 and R.sup.2 are as defined above to a phosphonium salt formation reaction with a phosphine compound of the following general formula (2): wherein Ar is as defined above to form the (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound (3-Z).

##STR00001##

The present invention also relates to a compound of the following general formula (A): L(CH.sub.2).sub.3CH═CH(CH.sub.2).sub.5CH(OR.sup.1)(OR.sup.2) (A) wherein R.sup.1 and R.sup.2 are as defined above.

The present invention relates to a process for preparing a (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound of the following general formula (3-Z): wherein Y represents a halogen atom, Ar represents, independently of each other, an aryl group, and R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 15 carbon atoms, or R.sup.1 and R.sup.2 may form together a divalent hydrocarbon group, R.sup.1-R.sup.2, having 2 to 10 carbon atoms, the process comprising: subjecting a (7Z)-11-halo-1,1-dialkoxy-7-undecene compound of the following general formula (1-Z): wherein X.sup.1 represents a halogen atom, and R.sup.1 and R.sup.2 are as defined above to a phosphonium salt formation reaction with a phosphine compound of the following general formula (2): wherein Ar is as defined above to form the (4Z)-11,11-dialkoxy-4-undecenyltriarylphosphonium halide compound (3-Z).

##STR00001##

The present invention also relates to a compound of the following general formula (A): L(CH.sub.2).sub.3CH═CH(CH.sub.2).sub.5CH(OR.sup.1)(OR.sup.2) (A) wherein R.sup.1 and R.sup.2 are as defined above.

The present invention is directed to a process for the manufacture of 1,1,4,4-tetramethoxy-2-butene from 2,5-dimethoxy-2,5-dihydrofuran with methanol in the presence of an acidic ion exchanger as catalyst, whereby the molar ratio of 2,5-dimethoxy-2,5-dihydrofuran to methanol is ≥1:45. The present invention is further directed to a process of separating 1,1,4,4-tetramethoxy-2-butene, methanol and 2,5-dimethoxy-2,5-dihydrofuran from each other and H2O whereby a basic compound, preferably a basic metal salt or a basic ion exchanger, is present. Both processes can be carried out on an industrial scale, batch-wise or in continuous mode and are sustainable since the selectivity and the space-time-yields are high and less waste compared to known processes is produced. Further objects of the present invention are the use of a basic compound in the distillation of a mixture comprising H2O, 1,1,4,4-tetramethoxy-2-butene and 2,5-dimethoxy-2,5-dihydrofuran, as well as the use of an acidic ion exchanger as catalyst in a reaction of 2,5-dimethoxy-2,5-dihydrofuran with methanol to 1,1,4,4-tetramethoxy-2-butene, whereby the molar ratio of 2,5-dimethoxy-2,5-dihydrofuran to methanol is ≥1:45.