Terephthalic acid

Terephthalic acid

Chembox new
Name = Terephthalic acid
ImageFile = Terephthalic-acid-2D-skeletal.png ImageName = Terephthalic acid
OtherNames = Benzene-1,4-dicarboxylic acid
"para"-Phthalic acid
Section1 = Chembox Identifiers
CASNo = 100-21-0
RTECS = WZ0875000

Section2 = Chembox Properties
Formula = C6H4(COOH)2
MolarMass = 166.13 g/mol
Appearance = white crystals or powder
Density = 1.522 g/cm³
Solubility = 0.0017g in 100g H2O at 25°C
SolubleOther = Soluble in Dimethyl sulfoxide, DMF, and alkalies. Slightly soluble in ethanol, methanol, formic acid and sulfuric acid. [Sheehan, R.J. Terephthalic acid, dimethyl phthalate and isophthalic acid. In: Ullmann's encyclopedia of industrial chemistry. 5th completely revised ed. Vol. A 26. VCH Verlagsgesellschaft, 1995. p. 193-204]
MeltingPt = 427°C in a sealed tube
Melting_notes = sublimes at 402°C (675 K) in air
BoilingPt = sublimes
TriplePoint = 427°
pKa1=3.54 at 25°C
pKa2=4.46 at 25°C [ [http://www.intox.org/databank/documents/chemical/terephac/cie474.htm CHEMINFO: Terephthalic acid ] ]

Section3 = Chembox Structure
CrystalStruct =
Dipole = zero

Section7 = Chembox Hazards
ExternalMSDS =
EUClass = not listed
FlashPt =

Section8 = Chembox Related
Function = carboxylic acids
OtherFunctn = Phthalic acid
Isophthalic acid
Benzoic acid
p-Toluic acid
OtherCpds = p-Xylene
Polyethylene terephthalate
Dimethyl terephthalate

Terephthalic acid is one isomer of the three phthalic acids. It finds important use as a commodity chemical, principally as a starting compound for the manufacture of polyester (specifically PET), used in clothing and to make plastic bottles. It is also known as 1,4-benzenedicarboxylic acid, and it has the chemical formula C6H4(COOH)2. It has recently become an important component in the development of hybrid framework materials.


Phthalic acid (the ortho isomer of terephthalic acid) was obtained by French chemist Auguste Laurent in 1836 by oxidizing naphthalene tetrachloride, and, believing the resulting substance to be a naphthalene derivative, he named it naphthalenic acid. Swiss chemist Jean Charles Galissard de Marignac determined its formula and showed Laurent’s supposition to be incorrect, upon which Laurent gave it its present name, with teres meaning well-turned, refined, elegant in latin [ [http://www.archives.nd.edu/cgi-bin/lookup.pl?stem=teres Teres Definition] ] (symmetry increased over ortho and meta isomers).


It is almost insoluble in water, alcohol and ether; it sublimes rather than melting when heated. This insolubility makes it relatively awkward to work with, and up until around 1970 most crude terephthalic acid was converted to the dimethyl ester for purification.


Terephthalic acid can be formed in the laboratory by oxidizing para-diderivatives of benzene, or best by oxidizing caraway oil, a mixture of cymene and cuminol, with chromic acid.

On an industrial scale, terephthalic acid is produced, similar to benzoic acid, by oxidation of "p"-xylene by oxygen from air. This is done using acetic acid as solvent, in the presence of a catalyst such as cobalt-manganese, using a bromide promoter. The yield is close to 100%. The crude product is purified by hydrogenation while in a water solution to convert trace amounts of impurities to less harmful species. The solution is then cooled in a stepwise manner to crystallize out a highly pure terephthalic acid. Over 90% of the terephalate feedstock for the polyester industry uses this process, and all plants built within the last few decades are of this technology. Alternatively, but not commercially, it can be made, via the Henkel process (company) also known as Raecke process (patent holder), which involves the rearrangement of phthalic acid to terephthalic acid via the corresponding potassium salts. [cite journal
title = The Preparation of Terephthalic Acid from Phthalic or Benzoic Acid
author = Yoshiro Ogata, Masaru Tsuchida, Akihiko Muramoto
journal = Journal of the American Chemical Society
volume = 79
issue = 22
pages = 6005–6008
year = 1957
url =
doi = 10.1021/ja01579a043
] [cite journal
title = Further Studies on the Preparation of Terephthalic Acid from Phthalic or Benzoic Acid
author = Yoshiro Ogata, Masaru Hojo, Masanobu Morikawa
journal = Journal of Organic Chemistry
volume = 25
issue = 12
pages = 2082–2087
year = 1960
url =
doi = 10.1021/jo01082a003
] Terephthalic acid and dimethyl terephthalate are essentially all used as a monomer component in the production of polymers, principally polyethylene terephthalate (polyester or PET). World production in 1970 was around 1.75 million tonnes. [2] . By 2006, global PTA demand had substantially exceeded 30 million tonnes.


# 1911 Encyclopedia
# "Basic Organic Chemistry: Part 5, Industrial Products", J.M. Tedder, A. Nechvatal, A.H. Tubb (editors), John Wiley & Sons, Chichester, UK (1975).

External links

* [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc03/icsc0330.htm International Chemical Safety Card 0330]
* [http://physchem.ox.ac.uk/MSDS/TE/terephthalic_acid.html MSDS sheet]

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Look at other dictionaries:

  • terephthalic acid — [ter΄ef thal′ikas′id] n. [ TERE(BENE) + PHTHALIC ACID] a white crystalline powder, C6H4 (COOH) 2, produced by the oxidation of certain xylene hydrocarbons and used in making plastics, polyester fiber, etc …   English World dictionary

  • terephthalic acid — tereftalio rūgštis statusas T sritis chemija formulė C₆H₄(COOH)₂ atitikmenys: angl. terephthalic acid rus. терефталевая кислота ryšiai: sinonimas – 1,4 benzendikarboksirūgštis …   Chemijos terminų aiškinamasis žodynas

  • terephthalic acid — noun An aromatic dicarboxylic acid, benzene 1,4 dicarboxylic acid, used in the manufacture of polyesters See Also: terephthalate, phthalic acid …   Wiktionary

  • terephthalic acid — |teˌre]f|thalik , |terə] noun Etymology: International Scientific Vocabulary terebene + phthalic : a crystalline dicarboxylic acid C6H4(COOH)2 that is much less soluble and much higher melting than phthalic acid, that has been obtained by… …   Useful english dictionary

  • terephthalic acid — noun Etymology: International Scientific Vocabulary terebene, mixture of terpenes from distilled turpentine + phthalic acid Date: 1857 a p dicarboxylic acid C8H6O4 that is obtained especially by oxidation of xylene and is used chiefly in the… …   New Collegiate Dictionary

  • terephthalic acid — [ˌtɛrəf θalɪk] noun Chemistry a crystalline organic acid used in making polyester resins and other polymers. Origin C19: blend of terebic of or from turpentine (from terebinth) and phthalic acid …   English new terms dictionary

  • terephthalic acid — ter′eph•thal′ic ac′id [[t]ˈtɛr ɛfˈθæl ɪk, ˌtɛr [/t]] n. chem. a white, crystalline, water insoluble solid, C8H6O2, the para isomer of phthalic acid: used chiefly in the manufacture of resins and textile fibers • Etymology: 1855–60; tere(bic acid) …   From formal English to slang

  • terephthalic acid — /tɛrəfˌθælɪk ˈæsəd/ (say teruhf.thalik asuhd) noun a white, crystalline, water insoluble, carboxylic acid, benzene 1,4 dicarboxylic acid, C6H4(COOH)2, used in combination with glycols to form linear, crystalline fibres, as dacron and terylene …  

  • terephthalic acid — /ter ef thal ik, ter /, Chem. a white, crystalline, water insoluble solid, C8H6O2, the para isomer of phthalic acid: used chiefly in the manufacture of resins and textile fibers. [1855 60; TERE(BIC) + PHTHALIC] * * * …   Universalium

  • Terephthalic acid (data page) — This page provides supplementary chemical data on Tetrahydrofuran. = Material Safety Data Sheet = The handling of this chemical may incur notable safety precautions. It is highly recommend that you seek the Material Safety Datasheet (MSDS) for… …   Wikipedia

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