Difference Between DEHT and DEHP

Thekey differencebetween DEHT and DEHP is thatDEHT is a non-phthalate plasticizer, whereas DEHP is a phthalate plasticizer.

The terms DEHT and DEHP stand for two types of polymer materials which can be categorized as plasticizers. A plasticizer is a component we can add to a certain substance to increase theplasticityby softening and increasing the flexibility of that substance.

CONTENTS

1.Overview and Key Difference
2.What is DEHT
3.What is DEHP
4.Side by Side Comparison – DEHT vs DEHP in Tabular Form
5.概括

What is DEHT

The term DEHT stands fordioctyl terephthalate. Sometimes it is also abbreviated as DOTP. We can categorize it as a non-phthalate plasticizer. It is an organic compound having the chemical formula C₆H₄(CO₂C₈H₁₇)₂. This compound has two carboxylate groups at the para position of abenzylring. It is, therefore, a diester of terephthalic acid and it has two 2-ethylhexanol branched chains attached to the carboxylate group.

DEHT occurs as a colourless, viscous liquid. Since it is a type of plasticizer, we can use this liquid for the softening of polymers such asPVC塑料。因此，在通用的情况下，DEHT与DEHP和其他邻苯二甲酸盐类似，但是使用DEHT软化的作用可以在负调节压力下完成，这是一个优势。DEHT具有有价值的增塑特性，因此我们可以将其直接替换为DEHP。

There are two methods to manufacture DEHT: transesterification of dimethyl terephthalate with 2-ethylhexanol and direct esterification of terephthalic acid with 2-ethylhexanol. The transesterification process produces a byproduct:methanol, which can be purified to get pure methanol to be used in other applications. However, in the direct esterification method, the byproduct is water. Therefore, the second method is more environmentally friendly.

What is DEHP?

The term DEHP stands fordioctyl phthalate. It is an organic compound having the chemical formula C₆H₄(CO₂C₈H₁₇)₂. It is a common phthalate plasticizer. When considering the chemical structure of DEHP, it has two carboxylate groups in the ortho position of a benzyl ring. Therefore, we can recognize it as a diester of phthalic acid. It has two-branched chains of 2-ethylhexanol. DEHP occurs as a colourless and a viscous liquid at room temperature. It can dissolve in oil but cannot dissolve in water.

DEHP has favourable properties and low cost to be used as a plasticizer. It is a common phthalic plasticizer. Usually, plastics such as PVC contain 1-40% DEHP blended with other components. This polymer material is also used as a hydraulic fluid, and it is an important dielectric fluid in capacitors. The most common way of producing DEHP is the reaction between phthalic anhydride with 2-ethylhexanol.

什么是与众不同ce Between DEHT and DEHP?

术语DEHT代表二辛基二苯二甲酸酯，而术语DEHP代表邻苯二甲酸二链醛酯。DEHT和DEHP之间的主要区别在于DEHT是一种非邻苯二甲酸盐增塑剂，而DEHP是邻苯二甲酸酯增塑剂。此外，DEHT和DEHP之间的结构差异是DEHT的羧酸酯基在苄基环的Para位置，而DEHP的两个羧酸酯基在苄基环的正位。

Moreover, DEHT is less toxic than DEHP, so DEHT is used as a replacement for DEHP.

Below infographic summarizes the difference between DEHT and DEHP.

概括– DEHT vs DEHP

DEHT and DEHP are important plasticizing agents. DEHT stands for dioctyl terephthalate while DEHP stands for dioctyl phthalate. The key difference between DEHT and DEHP is that DEHT is a non-phthalate plasticizer whereas DEHP is a phthalate plasticizer.

Reference:

1. “Dioctyl Terephthalate.” Wikipedia, Wikimedia Foundation, 2 June 2020,Available here.
2. “Bis(2-Ethylhexyl) Phthalate.” Wikipedia, Wikimedia Foundation, 30 Apr. 2020,Available here.

Image Courtesy:

1. Ed（Edgar181）的“二辛基苯二甲酸酯” - 通过Commons Wikimedia
2. Dschanz的“ BIS（2-乙基己基）邻苯二甲酸酯” - 使用：BKCHEM（公共领域）通过：通过Commons Wikimedia