Naphthalene - production and uses
Sep 3,2021
Naphthalene was first isolated from coal tar in 1819 by Alexander Garden; it represents about 10% of this complex mixture of aromatics. The industrial importance of naphthalene dates from the latter half of the last century, owing mainly to the ease with which it can be converted into sulfonic acids and thence also to the naphthols, for use as dyestuffs intermediates.
Uses
The development of synthetic dyestuffs provided further impetus for advances in naphthalene chemistry. Towards the end of the last century, its oxidation into phthalic anhydride (PA) attained particular importance as a step in a successful route for the economical synthesis of indigo. In the 20th century, the classic uses of naphthalene have been extended into new areas, for example, the development of the naphthol AS dyes from the parent naphthols, and the production of PAbased plasticizers and pesticides. The most recent developments iIi the field of industrial naphthalene chemistry concern the production of alkylnaphthalenederivatives as solvents for use in carbonless copy papers, as well as the manufacture of naphthoquinone for the synthesis of anthraquinone.The main uses of naphthalene in Western Europe, Japan and the USA. Although in Japan and the USA the main use of naphthalene is the production of phthalic anhydride, in Western Europe naphthalene is used in large quantities for the production of dyestuffs and tanning agents, as well as for surface-active compounds.Refined coal-derived naphthalene (crystallization point above 80 Qq, produced by crystallization or sublimation, has a worldwide application for some 30,000 t as fumigants (moth balls). In order to obtain color-stability, this grade of naphthalene requires a particularly low content of unsaturated co-products (indenes).Although fonnerly commonly used as solvents, transfonner oils and chemical intennediates, the chloronaphthalenes are now of little commercial significance, because of their toxicity and environmental persistence.Production
Coal tar is the traditional feedstock for the recovery of naphthalene. The introduction of new cracking processes in the last decades has given rise to the availability of petroleum-based raw materials. In addition to coal-derived naphthalene, petroleum- derived naphthalene has been recovered since 1961 - predominantly in the USA - by dealkylation of the residues of ethylene production and of reformingand cat-cracker fractions which are rich in aromatics.The worldwide production of petroleum-derived naphthalene has been declining in the last decade, representing presently only around 5% of the total, since adequate supplies of coalbased naphthalene are available. Because of its high aromaticity, coal tar offers the most suitable source of naphthalene. In coal tar refining, rectification is used to produce a naphthalene fraction which, depending on the separation efficiency of the naphthalene column, can have a naphthalene content rising to over 90%.- Related articles
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See also
Product Name:8-bromo-1-chlorodibenzo[b,d]furan, Synonyms Dibenzofuran, 8-bromo-1-chloro-;1-chloro-8-bromo-dibenzofuran,CAS No. 2225909-61-3.... Sep 3,2021Pharmaceutical intermediates
Dimethyl sulfate is a colorless oily liquid, odorless to a faint onion-like odor. It is very toxic by inhalation. It is a combustible liquid and has a flash point of 182°F. It is slightly soluble in water and decomposed by water to give sul.... Sep 6,2021Organic Chemistry
Naphthalene
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