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Example of the use of the prefix "Des-"

Deoxybenzoin (top) contains one less hydroxy group than benzoin (bottom).

For comparison, the structural formula of benzoin.

In chemical nomenclature , the prefix Des- , also De- , is used to indicate that a substance is missing something compared to another substance (parent compound). After Des- or De- is indicated what is missing, followed by the designation (= name) of the master connection.

Richard Willstätter also used this notation for the ring opening of a base with the empirical formula unchanged .

Dehydro

If a hydrogen atom is “missing” on two adjacent sp ³ -hybridized carbon atoms compared to the parent compound and the two carbon atoms (now sp ² -hybridized) are now connected by a C = C double bond, the addition prefix “Dehydro-” is used. If two hydroxyl groups opposite the parent compound become two carbonyl groups , the prefix dehydro- is also used. So z. B. from ascorbic acid (= parent compound) dehydroascorbic acid . Similarly, from cholic the dehydrocholic , a physiologically important bile acid .

Desmethyl

“Desmethyl-” means that a methyl group is “missing” from a parent compound and this has been replaced by a hydrogen atom. The Des carotenoids all methyl groups are missing.

Desmethoxy

“Desmethoxy-” means that a methoxy group is missing from a parent compound and has been replaced by a hydrogen atom.

Deoxy

Deoxysugars are carbohydrates in which a hydroxyl group has been replaced by a hydrogen atom. Deoxyribose (2-deoxy- D- ribose) is of particular importance as an important component of deoxyribonucleic acids ( DNA ). Similarly, in deoxybenzoin, the benzoin hydroxyl group has been replaced by a hydrogen atom.

See also

• Deamination , the cleavage of a primary amino group from chemical compounds, e.g. B. Amino acids

Wiktionary: de-  - explanations of meanings, word origins, synonyms, translations

Wiktionary: des-  - explanations of meanings, word origins, synonyms, translations

Individual evidence

1. ^ ^{A b} Wolfgang Holland: The nomenclature in organic chemistry, VEB Deutscher Verlag für Grundstoffindustrie Leipzig, pp. 36–37.
2. ^ Philipp Fresenius and Klaus Görlitzer: Organic-chemical nomenclature , Wissenschaftliche Verlagsgesellschaft Stuttgart, 1991, 3rd edition, pp. 136-137, ISBN 3-8047-1167-7 .
3. ^ Brockhaus ABC Chemie , VEB FA Brockhaus Verlag Leipzig 1965, p. 277.
4. ↑ Philipp Fresenius and Klaus Görlitzer: Organic-chemical nomenclature , Wissenschaftliche Verlagsgesellschaft Stuttgart, 1991, 3rd edition, p. 138, ISBN 3-8047-1167-7 .
5. ^ Albert Gossauer: Structure and reactivity of biomolecules , Verlag Helvetica Chimica Acta, Zurich, 2006, p. 332, ISBN 978-3-906390-29-1 .
6. ↑ Philipp Fresenius and Klaus Görlitzer: Organic-chemical nomenclature , Wissenschaftliche Verlagsgesellschaft Stuttgart, 1991, 3rd edition, p. 138, ISBN 3-8047-1167-7 .
7. ^ Brockhaus ABC Chemie , VEB FA Brockhaus Verlag Leipzig 1965, p. 276.