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Phthalic anhydride freezing points

This compound finds a ready market principally for the production of phthalic anhydride. There is a great variety of processes to isolate napthalene from the acid-free or neutral oils. Frequently, the naphthalene is first concentrated by distillation, and the enriched oil then is worked up by crystallization. This process is prevalent in Europe. It is also possible to isolate the naphthalene by careful fractionation. Depending on the purity desired, additional chemical treatments may be required. Naphthalene usually is traded with freezing point as a measure of purity (80.3°C) for pure naphthalene. A good quality commonly used is 78°C naphthalene, which is about 96% pure. [Pg.408]

TEMPERATURE TRANSFER STANDARD. A device for the transfer of a temperature scale from one standardizing laboratory to another. One form consists of a sample of a purified material, the freezing point of which (when realized by a prescribed technique) is reproducible within narrow limits. Materials commonly employed are metals, such as zinc and tin, and organic compounds, such as benzoic acid, phenol, naphthalene, and phthalic anhydride. Another form is a tungsten ribbon-filament lamp, characterized by a stable lamp current-brightness temperature relation. This device is particularly useful for temperatures above 1.050WC. [Pg.1599]

Fm. 40.—Freezing point curves fur the system phthalic anhydride - naphthalene (Mon-nic). ... [Pg.409]

Fie. 41.—Freezing point cnrxch for the system phthalic acid-phtlialic anhydride (Monroe). "1... [Pg.409]

Acetic and benzoic anhydrides give four fold freezing point depressions in sulfuric acid (134) but because of their instability (221) one cannot be sure whether they are completely protonated. Phthalic and succinic anhydrides are only partially protonated in this medium (134,221). However, against ethanol as a hydrogen-bond donor acetic anhydride is more basic than ethyl acetate (64). [Pg.299]


See other pages where Phthalic anhydride freezing points is mentioned: [Pg.644]    [Pg.630]   
See also in sourсe #XX -- [ Pg.409 ]




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