Question

Common Uses Name an aldehyde, ketone, carboxylic acid, ester, or amide used for each of the following purposes. a. preserving biological specimens b. solvent in fingernail polish c. acid in vinegar d. flavoring in foods and beverages

Short answer

a. Formaldehyde (aldehyde) is used for preserving biological specimens. b. Acetone (ketone) is used as a solvent in fingernail polish. c. Acetic acid (carboxylic acid) is the acid found in vinegar. d. Ethyl acetate (ester) is used as a flavoring in foods and beverages.

Step-by-step solution

Purpose A: Preserving biological specimens

Formaldehyde is an aldehyde commonly used for preserving biological specimens. Formaldehyde is a strong disinfectant and helps in preserving the structure and shape of organs and tissues.

Purpose B: Solvent in fingernail polish

Acetone is a ketone that is commonly used as a solvent in fingernail polish formulations. Acetone has a strong solvency power that makes it ideal for dissolving other ingredients in nail polish, such as resins and plasticizers.

Purpose C: Acid in vinegar

Acetic acid is a carboxylic acid that is responsible for the characteristic taste and smell of vinegar. It is produced through the fermentation of ethanol by acetic acid bacteria.

Purpose D: Flavoring in foods and beverages

Ethyl acetate is an ester commonly used as a flavoring in foods and beverages. It has a sweet fruity smell and can be found naturally in fruits, like apples and bananas, as well as in wine and other fermented products.

Key concepts

Aldehydes

Aldehydes are organic compounds characterized by the presence of a carbonyl group, which is a carbon double-bonded to oxygen, with at least one hydrogen atom attached to the carbon. They are highly reactive due to this carbonyl group, which can easily participate in various chemical reactions. A common example is formaldehyde, known for its use in preserving biological specimens. Formaldehyde effectively disinfects and maintains the structural integrity of tissues.

This makes it invaluable in laboratories and medical facilities. Aldehydes can also act as intermediates in chemical synthesis, serving as a precursor to other complex molecules. Friendly note: when dealing with aldehydes, it's critical to handle them with care as some like formaldehyde can have strong odors and may be harmful at high concentrations.

Ketones

Ketones are another class of organic compounds that like aldehydes, contain a carbonyl group. However, the carbon in ketones is bonded to two other carbon atoms, making them generally less reactive than aldehydes. A well-known ketone you probably encounter frequently is acetone, which is used as a solvent in fingernail polish removers due to its ability to dissolve other substances effectively.

This property allows it to break down the hardened layers of nail polish with ease. Ketones find applications beyond cosmetics; they are important in industry for solvents and in the synthesis of various chemicals. An interesting fact about ketones is their ability to form through the oxidation of alcohols, which can be part of certain metabolic processes within the body.

Carboxylic Acids

Carboxylic acids are organic acids containing a carboxyl group, which is a combination of a carbonyl and a hydroxyl group attached to the same carbon. Acetic acid is a typical example that gives vinegar its sour taste and characteristic smell. This type of acid is produced via the fermentation of ethanol, involving acetic acid bacteria.

Carboxylic acids play vital roles in organic chemistry, from participating in biochemical processes such as the Krebs cycle, to serving as building blocks for more complex molecules including esters and amides. These acids can vary in length and saturation, with acetic acid being quite short while others like oleic acid are longer and less saturated.

Esters

Esters are formed when a carboxylic acid reacts with an alcohol, resulting in the replacement of the hydrogen in the hydroxyl group with an alkoxy group. This reaction is called esterification and often requires an acidic catalyst. Esters are well-known for their pleasant aromas and are commonly used in perfumes and flavorings.

Ethyl acetate is an ester frequently used to impart fruity notes in foods and beverages. Esters are not only important in food and smell but are also found in biological systems where they are part of fats and oils. Their ability to dissolve in organic solvents also makes them useful in various industrial applications, such as varnishes and paints.

Amides

Amides are derived from carboxylic acids where the hydroxyl group is replaced by an amino group (NH₂). This transformation can occur through a variety of chemical routes, such as the reaction of an acid chloride with ammonia. Amides are essential in both synthetic and natural chemistry.

They form the backbone of proteins, making them crucial to life. Due to the presence of the carbonyl group, amides have interesting properties like relatively high melting points and the ability to form hydrogen bonds. These properties make them vital in drug formulation and the production of polymers like nylon. Understanding the chemical behavior of amides leads to innovations in materials science and pharmaceuticals.