CHEMISTRY GLOSSARY

polysaccharide    →   polisaharid

Polysaccharides are compounds consisting of a large number of simple sugars (monosaccharides) linked together by glycosidic bonds. When polysaccharides are composed of a single monosaccharide building block, they are termed homopolysaccharides. Heteropolysaccharides contain two or more different types of monosaccharide. Polysaccharides may have molecular weights of up to several million and are often highly branched. Since they have only the one free anomeric -OH group at the end of a very long chain, polysaccharides aren’t reducing sugars and don’t show noticeable mutarotation. The most common polysaccharides are cellulose, starch, and glycogen.

sucrose    →   saharoza

Sucrose (saccharose), or ordinary table sugar, is a disaccharide in which α-D-glucopyranose and β-D-fructofuranose are joined at their anomeric carbons by a glycosidic bond. There are no hemiacetals remaining in the sucrose and therefore sucrose is not a reducing sugar and does not exhibit mutarotation. Sugar is a white crystalline sweet compound found in many plants and extracted from sugar cane and sugar beet. It is used as a sweetening agent in food and drinks. If heated to 200 °C, sucrose becomes caramel. When sucrose is hydrolyzed it forms an equimolar mixture of glucose and fructose. This mixture of monosaccharides is called invert sugar. Honeybees have enzymes called invertases that catalyze the hydrolysis of sucrose. Honey, in fact, is primarily a mixture of glucose, fructose, and sucrose.

Chitin    →   Hitin

Chitin is a nitrogen-containing linear polysaccharide of ß(1->4) linked units of N-acetyl-ß-d-glucosamine. The structure of chitin is similar to cellulose except for the replacement hydroxyl group (-OH) at the carbon 2 with an acetyl amine group (–NH–CO–CH3). Chitin is the main component of the exoskeleton, or outer covering of insects, crustaceans, and arachnids. It is also found in the cell walls of certain fungi and algae. After cellulose, chitin is the second most abundant biopolymer in nature. It is insoluble in water, organic solvents, weak acids and lyes.

acetal    →   acetal

Acetals are organic compounds having the structure R₂C(OR’)₂ (R’ ≠ H). They are organic compounds formed by addition of alcohol molecules to aldehyde or ketone molecules. Originally, the term was confined to derivatives of aldehydes (one R = H), but it now applies equally to derivatives of ketones (neither R = H ). Mixed acetals have different R’ groups. The formation of acetals is reversible; acetals can be hydrolysed back to aldehydes (ketone) in acidic solutions.

Acetal, 1,1-diethoxyethane (CH₃CH(OC₂H₅)₂), is an organic compound, pleasant smelling, formed by addition of ethyl alcohol to ethanal (acetaldehyde). It is used as a solvent and in synthetic organic chemistry.

actinides    →   aktinoidi

Actinides (actinons or actinoids) are the fourteen elements from thorium to lawrencium inclusive, which follow actinium in the periodic table. The position of actinium is somewhat equivocal and, although not itself an actinide, it is often included with them for comparative purpose. The series includes the following elements: thorium (Th), protactinium (Pa), uranium (U), neptunium (Np), plutonium (Pu), amercium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm), mendelevium (Md), nobelium (No) and lawrencium (Lr). Every known isotope of the actinide elements is radioactive. Traces of Pa, Np and Pu are consequently found, but only Th and U occur naturally to any useful extent.

alkaloid    →   alkaloid

Alkaloids are basic nitrogen organic compounds (mostly heterocyclic) derived from plants and having diverse pharmacological properties. Alkaloids include morphine, cocaine, atropine, quinine, and caffeine, most of which are used in medicine as analgesics or anaesthetics. Some alkaloids are poisonous, e.g. strychnine and coniine, and colchicine inhibit cell division.

amines    →   amini

Amines are compounds formally derived from ammonia by replacing one, two, or three hydrogen atoms by hydrocarbyl groups, and having the general structures RNH₂ (primary amines), R₂NH (secondary amines), R₃N (tertiary amines). Examples are methylamine, CH₃NH₂; dimethylamine, CH₃NHCH₃; and trimethylamine, (CH₃)₃N.

amino acids    →   aminokiseline

Amino acids are compounds containing both a carboxylic acid group (-COOH) and an amino group (-NH₂ ). The most important are the α-amino acids, in which the -NH₂ group in attached to the C atom adjacent to the -COOH group. In the β-amino acids, there is an intervening carbon atom.

anion    →   anion

Anion is a negatively charged atomic or molecular particle.

alcohol    →   alkohol

Alcohols are compounds in which a hydroxy group, -OH, is attached to a saturated carbon atom. Smaller members are water soluble, inflammable and are useful as organic solvents and fuels.