Citral

• 3,7- Dimethylocta -2 ,6- dienal
• (E) -3,7- Dimethylocta -2 ,6- dienal ( geranial )
• (Z) -3,7- Dimethylocta -2 ,6- dienal ( Neral )

Light yellow liquid with lemon -like odor

Liquid

0.89 g · cm -3

<-20 ° C

225 ° C

<1 hPa ( 50 ° C)

Insoluble in water (420 mg · l-1 at 20 ° C)

1.4898 (20 ° C)

Attention

• 6000 mg · kg -1 ( LD50, mouse, oral)
• 4960 g · kg -1 ( LD50, rat, oral)

Template: Infobox chemical / molecular formula search available

Citral is the mixture of the stereoisomers geranial ( citral A) and neral ( citral B). Geranial can be found as a fragrance, inter alia, in tomato in small amounts as a degradation product of lycopene. Citral is the main constituent of lemongrass oil. There is alarm pheromone of the leaf -cutting ant.

Properties

The CAS number of 5392-40-5 Citral is that the Nerals 106-26-3 and 141-27-5 of the Geranials. The IUPAC name for citral is 3,7- Dimethylocta -2 ,6- dienal. It is acyclic monoterpene aldehydes. Citral is a pale yellow liquid with intense fresh lemon scent. The mixture boils at 228 ° C in water, it is almost insoluble. Citral acts in pure form as well as in the mixture in concentrations from 1% irritating to the skin.

Use

Citral is used as a fragrance and flavoring agent. According to the seventh supplement to the EU Cosmetics Directive 76/768/EEC, it must be declared as a cosmetic ingredient because of potential allergens.

Reactions

Neral and geranial can be prepared by dehydration of nerol and geraniol. Citral reacts with acetone in an alkaline medium ( for example, barium ) first underwater delivery for pseudoionone. This may then be converted in the presence of acids and elevated temperatures in the isomer ionone.

In an alkaline environment, it may also in acetaldehyde and 2- methylhept -2 -en- 6-one decay ( retro-aldol reaction).

The heterogeneously catalyzed hydrogenation in the presence of palladium catalysts via the intermediate stage of citronellal with about 86 % yield Dihydrocitronellal.