Uses of Aldehydes and Ketones:

Aldehydes and ketones are used in a wide variety of fields including industrial, pharmaceutical and medical fields. Examples are given below:

Formaldehyde: Formaldehyde (made predominantly by the oxidation of methanol) is a gas but is generally handled as a 37 percent solution in water, called formalin. It is used in tanning, preserving, and embalming and as a germicide, fungicide, and insecticide for plants and vegetables, but its largest application is in the production of certain polymeric materials. The plastic Bakelite is made by a reaction between formaldehyde and the aromatic compound phenol.

Formaldehydes are also invloved in some recations that are used to form strong adhesives like ones used in plywood.

Acetone: Acetone is one of the few organic compounds that is infinitely soluble in water (i.e., soluble in all proportions) and also dissolves many organic compounds. For this reason and because of its low boiling point (56º C), which makes it easy to remove by evaporation when no longer wanted it is one of the most important industrial solvents, being used in such products as paints, varnishes, resins, coatings, and nail-polish removers.

Other aldehydes and ketones of industrial significance are mainly used as solvents, perfumes, and flavouring agents or as intermediates in the manufactureof plastics, dyes, and pharmaceuticals.

Certain aldehydes occur naturally in flavouring agents. Among these are benzaldehyde, which provides the odour and flavour of fresh almonds; cinnamaldehyde, or oil of cinnamon; and vanillin, the main flavouring agent of vanilla beans.

In addition, certain aldehydes and ketones perform essential functions in humans and other living organisms. Some important examples are the carbohydrates (including sugars, starch, and cellulose), which are based on compounds that possess an aldehyde or ketone function along with hydroxyl groups; the steroid hormones, many of which, including progesterone, testosterone, cortisone, and aldosterone, are ketones; and retinal, an aldehyde, which, upon combining with a protein (opsin) in the retina of the eye to form rhodopsin, is the main compound involved in the process of vision. Exposure of rhodopsin to light initiates a cis-trans isomerization in the retinal portion. The change in molecular geometry is responsible for generating a nerve impulse that is sent to the brain and perceived as a visual signal.

Methadone: The ketone methadone (C21H27NO) has been used to cure addiction to opiates. Some common opiates are heroin, opium, and morphine. All of these drugs work by causing the body to release excessive amounts of the hormone dopamine. To help combat opiate addiction, the oral medication methadone can be prescribed by a medical professional. Methadone works by binding to the dopamine receptor in the brain. This eliminates the

Mahmoud Halawa Chemistry Assignment 12 G

user’s physical dependence on opiates because the user doesn’t need anything else to bind to the dopamine receptor.

Glutamaldehyde: Glutamaldehyde is a common cleaner. It kills bacteria, fungi, viruses, and more. Glutamate is able to attack the cell membrane and cell walls in bacteria and fungi, which prevents the cell from functioning. It also affects amino acids and causes proteins to denature. As proteins are responsible for many cell functions and make up cell DNA, this prevents the cell from functioning.

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Uses of Buffers:

Pharmaceutical industries

Many different therapeutic drugs are synthesised under restrict pH conditions to ensure the stability

and clinical effectiveness of these treatments. This is usually achieved with buffer solutions. In

addition, buffers can be used to:

Increase the drug’s shelf-life

Maintain the drug in a specific un-ionised or ionised form, depending on the type of

solution used. For example, ionised forms tend to be more soluble in water, while un-

ionised forms are more soluble in lipids

Maintain the drug in a near-neutral pH, this way avoiding any irritation to the body

tissues

Protect the drug against undesired hydrolysis in aqueous solutions

Fermentation

Fermentation reactions – such as in beer or yogurt – are highly affected by varying pH. This means

it’s essential to use buffer solutions to avoid harsh changes and allow fermentation to progress to

obtain maximum yield.

For example, in bread, the pH of the dough will naturally drop with the production of CO2 and some

other organic acids. In this case, both natural buffers milk and flour, as well as chemical products

such as calcium bicarbonate (CaCO3) can be used to limited pH variations during fermentation.

Mahmoud Halawa Chemistry Assignment 12 G

Specialised buffers are also used extensively in the food industry as food additives, in particular to

ensure the appearance and flavour of certain food items, as well as delaying any microbiological

“invasion”. These additives are usually weak acids or their respective salts already naturally present

in some foods.

Textile and leather industry

The textile and leather industry rely heavily on many different dyes to obtain different colours and

textures. The strength of some of these dyes is defined by its pH and drastic changes will affect the

colour and how the dye may react to a certain fabric.

For example, monosodium phosphate is commonly used to maintain a low pH for acidic dyeing of

textile fibres, whereas disodium phosphate is more useful within a mild alkali range to dye fabrics

that are sensitive to extreme pH conditions.

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Uses of esters:

Some of the most important uses of Esters are :-

1. Esters are used for making artificial flavours and essences. These are used in cold drinks, ice-creams, sweets and perfumes.

2. Esters are used as solvents for oils, fats, gums, resins, cellulose, paints, varnishes, etc.

3. Esters are used as plasticizers.

Mahmoud Halawa Chemistry Assignment 12 G

Mahmoud Halawa Chemistry Assignment 12 G