Fragrance raw materials monographs 667

CITRAL DIETHYL ACETAL

Synonyms: 1,1-Diethoxy-3,7-dimethyl-2,6-octadiene; 3,7-dimethyl-2,6-octadienal diethyl acetal. Structure: CH3" C(CH3) :CH. [CH212" C(CH3):CH" CH(OCH2' CH3)" OCH2 CH3. Description and physical properties: A colourless liquid. Occurrence: Has apparently not been reported to occur in nature. Preparation: From ethyl orthoformate and citral (Fenaroli's Handbook o f Flavor Ingredients, 1975). Uses: Concentration in final product (%):

Soap Detergent Creams, lotions Perfume Usual 0.03 0.005 0.03 0.05 Maximum 0.15 0.02 0.15 0.4

Status

Citral diethyl acetal was given GRAS status by FEMA (1965), is approved by the FDA for food use (21 CFR 172.515) and was included by the Council of Europe (1981), with an ADI of 0.5 mg/kg body weight for total citral and citral acetals, in the list of flavouring substances that may be added to foodstuffs without hazard to public health. CAS Registry No. 7492 66-2.

Biological data*

Acute toxicity. Both the acute oral LDs0 in rats and the acute dermal LDs0 in rabbits exceeded 5 g/kg (Moreno, 1980).

Irritation. Citral diethyl acetal applied full strength to intact or abraded rabbit skin for 24 hr under occlusion was moderately irritating (Moreno, 1980). Tested at 4% in petrolatum, it produced no irritation after a 48-hr closed-patch test on human subjects (Epstein, 1980).

Sensitization. A maximization test (Kligman, 1966; Kligman & Epstein, 1975) was carried out on 28 volunteers. The material (RIFM no. 79-325) was tested at a concentration of 4% in petrolatum and produced no sensitization reactions (Epstein, 1980). Closed epicutaneous tests on 18 com- positions containing citral diethyl acetal in concentrations ranging from 0.5 to 5% (mean 1.69%) produced no reactions in volunteer panels of 60 or 100 test subjects (IFRA, 1980). These 18 compositions were also tested by a series of open epicutaneous tests in guinea-pigs and produced no sensitization reactions (IFRA, 1980). Five perfume compositions containing citral diethyl acetal in concentrations ranging from 1 to 2% (mean 1.4%) were tested on humans by the repeated insult patch test (RIPT) and produced no sensitization reactions (IFRA, 1980).

References

Council of Europe (1981). Flavouring Substances and Natural Sources of Flavourings. Partial Agreement in the Social and Public Health Field. 3rd Ed. List I, no. 38, p. 131. Strasbourg.

Epstein W. L. (1980). Report to RIFM, 29 February. Fenaroli's Handbook o[Flavor Ingredients (1975). 2nd Ed. Edited b~ T. E. Furia & N. Bellanca. Vol. II, p. 100.

CRC Press, Cleveland, OH. Flavoring Extract Manufacturers' Association (1965). Survey of flavoring ingredient usage levels. No. 2304. Fd

Technol., Champaign 19 (2), part 2, 155. IFRA (1980). Personal communication to RIFM, 5 May. Kfigman A. M. (1966). The identification of contact allergens by human assay. III. The maximization test. A

procedure for screening and rating contact sensitizers. J. invest. Derm. 47, 393. Kligman A. M. & Epstein W. (1975). Updating the maximization test for identifying contact allergens. Contact

Dermatitis 1, 231. Moreno O. M. (1980). Report to RIFM, 14 March.

Additional reference

Flavor and Extract Manufacturers' Association (1975). Scientific literature review of aliphatic acetals in flavor usage. Food and Drug Administration Report FDA/BF-77/54, Vol. 1, pp. 72. National Technical Information Service Report No. PB-265 514.

*Literature searched from 1962 through 1981.