[Chemistry Class Notes] on Citral Pdf for Exam

Citral (C₁₀H₁₆O) is a pale yellow liquid, and it has a strong lemon-like odour. It is also called 3,7-dimethyl-2, c-octadienal. Citral can not be mixed well with water, which means it is insoluble in water, but it is soluble in ethyl odour (ethanol), Mineral oil, and diethyl ether. It is mainly used in the manufacturing of perfumes and other smelling chemicals. Moreover, citral is a combination or mixture of two different aldehydes with different structures and the same molecular formula. Citral is known for its acceptable, distinct, and lemon-like pleasant smell. Mehylionene and lonone are made from citral and used in perfumery. It can be synthesized from myrcene, and ionene can be converted into synthetic Vitamin A. 

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Properties of Citral

Two compounds are double bond isomers.

There are two types of citrals, citral A is E-isomer, and citral B is Z-isomer. Isomer geraniol has a lemon-like smell, and isomer neral has a less intense and sweeter lemon-like smell.

Physical Properties of Citral

• Citral is a clear yellow-coloured fluid with a lemon-like fragrance.

• The density of citral is 0.9 g/cm³.

• Less dense than water.

• Insoluble in water.

• The melting point of citral is <-10°C

• Citral is not persistent to alkanes and strong acid

• When heated to decomposition, it emits acrid smoke and irritating fumes.

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Citral Uses

Citral is commonly used in beverages, foods, cosmetics, and other products. Its possible carcinogenic effects were investigated because of its versatile use in many products like citral oil and citral good scents. Moreover, in the investigation, two rats – one male and one female were used. Male mice were subjected to microencapsulated pure citral (500-4000 ppm) in food for 14 weeks or two years. Well, researchers could not find any proven data of carcinogenic activity of pure citral in mice and rats (According to anonymous data).

Well, citral is used as the flavouring agent and natural additive ingredient in foods, beverages, and cosmetics. Citral has properties of the acidic environment and chemical instability; hence its application domains are limited. Well, degradation of citral has been an industrial issue for many years, and it is a challenging task for ten years. In addition, the ways of citral degradation retarding are also some of the reasons for the limited use of o citral. Decreasing temperature, removing oxygen, and neutralizing pH are some ways of the citral degradation retarding process. The antioxidation process can prevent citral degradation, but this process is not available for non-commercially extensive extraction and costly processes. Moreover, antioxidants are not always suited as some antioxidants may add undesirable colour and taste to food products. Citral is also used as ingredients of citral sigma products that are very popular.

Citral Oil

Citral is a natural substance that can be obtained from plant oils. Lemongrass oil contains 75 to 80 % citral that may be isolated through the distillation process. Some other natural sources include verbena oil and citronella oil. Citral can be obtained from myrcene. It is generally found in the peel of the orange. Because of their intense aroma and flavour are used in beverages, perfumes, cosmetics, and food. Essential oils that present citral shows antifungal, antimicrobial, antiparasitic features that make it a natural preservative. 

Citral Medicinal Uses 

Citral has beautiful features like incense, anti-inflammatory, antibacterial, etc. It can also be used as a bug repellent. Here are some properties described that add values of citral to be used in medicines.

Antibacterial: Citral has strong antimicrobial properties in addition to fragrance. A study of Letters In Applied Microbiology declared that citral shows antimicrobial activity against gram-negative and gram-positive bacteria and fungus.

Anti-Inflammatory: Citral may also possess anti-inflammatory properties. A 2017 study on mice found that citral showed a significant decrease in TNF-α (Tumor Necrosis Factor-alpha) levels in tests demonstrating anti-inflammatory activity.

Bug-Repellent: Citral is one of the active components of citronella oil, a common ingredient used in insect repellents and citronella candles. Citronella has been registered as a gentle, plant-based insect repellent in the United States since 1948. Some evidence suggests that citral and the other active compounds in citronella interfere with mosquito olfactory receptors.