Terephthalic acid

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Terephthalic acid

Terephthalic acid is the organic compound

Organic compound

An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered Inorganic compound....
and one of three isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulae. Isomers do not necessarily share similar properties unless they also have the same functional groups....
ic phthalic acids, all with formula

Chemical formula

A chemical formula is a way of expressing information about the atoms that constitute a particular chemical compound, and how the relationship between those atoms changes in chemical reactions....
C₆H₄(CO₂H)₂. This colourless solid is a commodity

Commodity

A commodity is anything for which there is demand, but which is supplied without qualitative product differentiation across a market. It is a product that is the same no matter who produces it, such as petroleum, notebook paper, or milk....
chemical

Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
, principally as a starting compound for the manufacture of the polyester

Polyester

Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate ....
PET

Polyethylene terephthalate

Polyethylene tephthalate , commonly abbreviated PET, PETE, or the obsolete PETP or PET-P), is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid Packaging; thermoforming applications; and engineering resins often in combination with glass fiber....
, used to make clothing and plastic bottles. It has recently been popularized as a component in hybrid framework

Metal-organic framework

Metal-Organic Frameworks are crystalline compounds consisting of metal ions or clusters coordinated to often rigid organic molecules to form one-, two-, or three-dimensional structures that can be porous....
materials.

s almost insoluble in water, alcohol and ether; it sublimes rather than melting when heated.

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Properties

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

Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
for purification.

Production

On an industrial scale, terephthalic acid is produced by oxidation of p-xylene

Xylene

The term xylene or xylol refers to a mixture of three aromatic hydrocarbon isomers which is used as a solvent in the printing, rubber, and leather industries....
by oxygen

Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
in air

AIR

Air is the part of Earth's atmosphere that humans breath and as such Air .Air may also refer to:...
:

The oxidation is conducted using acetic acid

Acetic acid

Acetic acid, CH3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. Pure, water-free acetic acid is a colourless liquid that absorbs water from the environment , and freezes at 16.7 Celsius to a colourless crystalline solid....
as solvent

Solvent

A solvent is a liquid or gas that dissolves a solid, liquid, or gaseous solute, resulting in a solution.The most common solvent in everyday life is water....
and a catalyst composed of cobalt

Cobalt

Cobalt is a hard, lustrous, grey metal, a chemical element with symbol Co and atomic number 27. Although cobalt-based colors and pigments have been used since ancient times, and miners have long used the name kobold ore for some minerals, cobalt was only discovered in 1735 by Georg Brandt....
and manganese

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a Oxidation state in nature , and in many minerals....
salts, using a bromide

Bromide

A bromide ion is a bromine atom with electric charge of -1.Compounds with bromine in formal oxidation state -1 are called bromides, and each individual chemical in this class can be called a bromide, as well....
promoter. The yield is nearly quantitative. The most problematic impurity is 4-formylbenzoic acid, which is removed by hydrogenation

Hydrogenation

Hydrogenation is the chemical reaction that results from the addition of hydrogen . The process is usually employed to a redox or Saturation organic compounds....
of a hot aqueous solution. The solution is then cooled in a stepwise manner to crystallize highly pure terephthalic acid.

Alternatively, but not commercially significant, is the so-called "Henkel process" or "Raecke process," named after the company and patent holder, respectively. This process involves the rearrangement of phthalic acid

Phthalic acid

Phthalic acid is an aromatic dicarboxylic acid, with formula C6H42. It is an isomer of isophthalic acid and terephthalic acid....
to terephthalic acid via the corresponding potassium salt

Salt

A salt, in chemistry, is defined as the product formed from the neutralisation reaction of acids and base . Salts are ionic compounds composed of cations and anions so that the product is electrically electric charge ....
s. Terephthalic acid can be formed in the laboratory by oxidizing para-diderivatives of benzene

Benzene

Benzene, or benzol, is an organic compound chemical compound and a known carcinogen with the molecular formula Carbon6Hydrogen6....
, or best by oxidizing Caraway Oil, a mixture of cymene

Cymene

Cymene, or p-cymene, is a naturally occurring aromatic organic compound. It is classified as a hydrocarbon related to a terpene. Its structure consists of a benzene ring para-substituted with a methyl group and an isopropyl group....
and cuminol, with chromic acid

Chromic acid

Chromic acid generally refers to a collection of chemical compound generated by the acidification of solutions containing chromate and dichromate ion or the dissolving of chromium trioxide in sulfuric acid....
.

Applications

Terephthalic acid and dimethyl terephthalate

Dimethyl terephthalate

Dimethyl terephthalate is an ester of terephthalic acid and methanol and is used in the production of polyesters, including polyethylene terephthalate and polytrimethylene terephthalate....
are essentially completely consumed as precursors to polymer

Polymer

A polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties....
s, principally polyethylene terephthalate

Polyethylene terephthalate

Polyethylene tephthalate , commonly abbreviated PET, PETE, or the obsolete PETP or PET-P), is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid Packaging; thermoforming applications; and engineering resins often in combination with glass fiber....
(polyester or PET). World production in 1970 was around 1.75 million tonnes. By 2006, global purified terephthalic acid (PTA) demand had exceeded 30 million tonnes.

Terephthalic acid

Properties

Production

Applications

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