Diethyl maleate is an organic compound classified as a diester of maleic acid. Here's a breakdown of its key chemical aspects:

Chemical Formula: C?H??O?

Structural Formula:

     O             O

    ║             ║

CH?CH?-O-C-CH=CH-C-O-CH?CH?

• It consists of a maleate core (the cis isomer of -OOC-CH=CH-COO-) esterified with two ethyl groups (-CH?CH?).

• The central feature is the electron-deficient double bond (C=C) activated by the two flanking electron-withdrawing ester groups (-COOCH?CH?). This makes the double bond highly reactive towards nucleophiles (Michael addition).

  Systematic Name: Diethyl (Z)-but-2-enedioate

• The "(Z)" designation explicitly indicates the cis configuration around the double bond, which is inherent to maleic acid derivatives.

  CAS Number: 141-05-9

  Physical Properties:

• Appearance: Colorless to pale yellow liquid.

• Odor: Characteristic ester-like odor.

• Boiling Point: ~220 °C (428 °F)

• Density: ~1.07 g/cm3

• Solubility: Insoluble in water; miscible with most organic solvents (ethanol, ether, benzene, oils).

  Key Chemical Properties:

• Michael Additions: Nucleophiles (amines, thiols, carbanions) add across the double bond.

• Diels-Alder Reactions: Acts as a dienophile.

• Free Radical Additions.

• Hydrogenation: Can be reduced to the saturated diester (diethyl succinate).

• Reactive Double Bond: The primary reactivity stems from the activated alkene. It readily undergoes:

• Ester Groups: Can undergo typical ester reactions like hydrolysis (back to maleic acid), transesterification, or aminolysis, although the double bond reactivity often dominates.

• Isomerization: Can isomerize to the thermodynamically more stable trans isomer, diethyl fumarate, under certain conditions (heat, catalysts).

  Primary Uses:

• Chemical Intermediate: Widely used in organic synthesis, especially as a Michael acceptor to build more complex molecules or introduce maleate functionality.

• Biochemical Research Tool: Its most famous application is as a specific depletor of cellular glutathione (GSH). It rapidly conjugates with GSH via Michael addition catalyzed by glutathione S-transferase (GST), allowing researchers to study the role of GSH in cellular processes like detoxification, oxidative stress, and toxicity.

• Plasticizer: Used in some plastics and resins, although less common than other plasticizers.

• Adhesives and Coatings: A component in some formulations.

• Insect Repellent/Synergist: Found in some insect repellent formulations.

  Safety and Handling:

• Toxicity: Harmful if swallowed, inhaled, or absorbed through skin. Causes skin and eye irritation.

• Target Organ Toxicity: Known to be nephrotoxic (kidney toxic) and hepatotoxic (liver toxic), partly due to its glutathione-depleting action.

• Environmental Hazard: Toxic to aquatic life.

• Precautions: Use with adequate ventilation (fume hood), wear gloves, eye protection, and other appropriate PPE. Avoid contact and inhalation.

In summary, diethyl maleate is a versatile synthetic organic chemical characterized by its diester structure and a highly reactive, electron-deficient double bond. Its reactivity makes it valuable as a chemical building block and a specific tool in biochemistry for studying glutathione, but it requires careful handling due to its toxicity.