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aldehyde(ăl`dəhīd) [alcohol + New Lat. dehydrogenatus=dehydrogenated], any of a class of organic compounds that contain the carbonyl groupcarbonyl group
, in chemistry, functional group that consists of an oxygen atom joined by a double bond to a carbon atom. The carbon atom is joined to the remainder of the molecule by two single bonds or one double bond.
..... Click the link for more information. , , and in which the carbonyl group is bonded to at least one hydrogen; the general formula for an aldehyde is RCHO, where R is hydrogen or an alkyl or aryl group. Aldehydes are formed by partial oxidation of primary alcohols and form carboxylic acids when they are further oxidized. The common name for an aldehyde is often derived from the name of the acid it forms; the IUPAC name is usually derived from the name of the alcohol from which it is formed. Low molecular weight aldehydes, e.g., formaldehydeformaldehyde
, HCHO, the simplest aldehyde. It melts at −92°C;, boils at −21°C;, and is soluble in water, alcohol, and ether; at STP, it is a flammable, poisonous, colorless gas with a suffocating odor.
..... Click the link for more information. and acetaldehydeacetaldehyde
, CH3CHO, colorless liquid aldehyde, sometimes simply called aldehyde. It melts at −123°C;, boils at 20.8°C;, and is soluble in water and ethanol.
..... Click the link for more information. , have sharp, unpleasant odors; higher molecular weight aldehydes, e.g., benzaldehydebenzaldehyde
, C6H5CHO, colorless liquid aldehyde with a characteristic almond odor. It boils at 180°C;, is soluble in ethanol, but is insoluble in water.
..... Click the link for more information. and furfuralfurfural
[Lat.,=bran], C4H3OCHO, viscous, colorless liquid that has a pleasant aromatic odor; upon exposure to air it turns dark brown or black. It boils at about 160°C;.
..... Click the link for more information. , have pleasant, often flowery, odors and are found in the essential oilsessential oils,
volatile oils that occur in plants and in general give to the plants their characteristic odors, flavors, or other such properties. Essential oils are found in various parts of the plant body (in the seeds, flowers, bark, or leaves) and are also concentrated in
..... Click the link for more information. of certain plants. Aldehydes are used for the manufacture of synthetic resins, e.g., bakelite, and for making dyestuffs, flavorings, perfumes, and other chemicals. Some are used as preservatives and disinfectants.
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One of a class of organic compounds containing the CHO radical.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
1. any organic compound containing the group -CHO. Aldehydes are oxidized to carboxylic acids and take part in many addition reactions
2. consisting of, containing, or concerned with the group -CHO
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005