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Thioacetal
 
 
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Thioacetals are the sulfur
Sulfur

Sulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant Valence non-metal....
 analogue
Analog (chemistry)

In chemistry, analogs or analogues are chemical compound in which one or more individual atoms have been replaced, either with a different atom, or with a different functional group....
 of acetal
Acetal

An acetal is a molecule with two single bonded oxygens attached to the same carbon atom.Traditional usages distinguish ketal from acetal . Current accepted terminology classifies ketals as a subset of acetals....
s. They are prepared in a similar way to acetals: by reacting a thiol
Thiol

In organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur atom and a hydrogen atom . Being the sulfur analogue of an alcohol group , this functional group is referred to either as a thiol group or a sulfhydryl group....
 with an aldehyde
Aldehyde

An aldehyde is an organic compound containing a terminal carbonyl group. This functional group, which consists of a carbon atom bonded to a hydrogen atom and double bond to an oxygen atom , is called the aldehyde group....
:
RSH + R'CHO → R'CH(OH)SR


Dithioacetals are prepared similarly to thioacetals, which are intermediates:
RSH + R'CH(OH)SR → R'CH(SR)2 + H2O


Such reactions typically employ either a Lewis
Lewis acid

A Lewis acid is a chemical compound, A, that can accept a pair of electrons from a Lewis base, B, that acts as an electron-pair donor, forming an adduct, AB.Gilbert N....
 or Brønsted acid catalyst.

Dithioacetals generated from aldehydes and 1,2-ethanedithiol
1,2-Ethanedithiol

1,2-Ethanedithiol is an odorous, colorless liquid with the formula C2H42. It is a common building block in organic synthesis and an excellent ligand for metal ions....
 are useful in organic synthesis
Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
:
C2H4(SH)2 + R'CHO → R'CHS2C2H4 + H2O


Whereas the carbonyl carbon of an aldehyde is electrophilic, the deprotonated derivatives of dithioacetals feature nucleophilic carbon centers:

R'CHS2C2H4 + R2NLi → R'CLiS2C2H4 + R2NH
Again, this reactivity is most commonly exploited in the 1,3-dithiolane
Dithiolane

A dithiolane is a sulfur heterocyclic compound derived from cyclopentane by replacing two methylene groups with thioether groups. The parent compounds are 1,2-dithiolane and 1,3-dithiolane....
s.






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Thioacetals are the sulfur
Sulfur

Sulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant Valence non-metal....
 analogue
Analog (chemistry)

In chemistry, analogs or analogues are chemical compound in which one or more individual atoms have been replaced, either with a different atom, or with a different functional group....
 of acetal
Acetal

An acetal is a molecule with two single bonded oxygens attached to the same carbon atom.Traditional usages distinguish ketal from acetal . Current accepted terminology classifies ketals as a subset of acetals....
s. They are prepared in a similar way to acetals: by reacting a thiol
Thiol

In organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur atom and a hydrogen atom . Being the sulfur analogue of an alcohol group , this functional group is referred to either as a thiol group or a sulfhydryl group....
 with an aldehyde
Aldehyde

An aldehyde is an organic compound containing a terminal carbonyl group. This functional group, which consists of a carbon atom bonded to a hydrogen atom and double bond to an oxygen atom , is called the aldehyde group....
:
RSH + R'CHO → R'CH(OH)SR


Dithioacetals are prepared similarly to thioacetals, which are intermediates:
RSH + R'CH(OH)SR → R'CH(SR)2 + H2O


Such reactions typically employ either a Lewis
Lewis acid

A Lewis acid is a chemical compound, A, that can accept a pair of electrons from a Lewis base, B, that acts as an electron-pair donor, forming an adduct, AB.Gilbert N....
 or Brønsted acid catalyst.

Dithioacetals generated from aldehydes and 1,2-ethanedithiol
1,2-Ethanedithiol

1,2-Ethanedithiol is an odorous, colorless liquid with the formula C2H42. It is a common building block in organic synthesis and an excellent ligand for metal ions....
 are useful in organic synthesis
Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
:
C2H4(SH)2 + R'CHO → R'CHS2C2H4 + H2O


Whereas the carbonyl carbon of an aldehyde is electrophilic, the deprotonated derivatives of dithioacetals feature nucleophilic carbon centers:

R'CHS2C2H4 + R2NLi → R'CLiS2C2H4 + R2NH
Again, this reactivity is most commonly exploited in the 1,3-dithiolane
Dithiolane

A dithiolane is a sulfur heterocyclic compound derived from cyclopentane by replacing two methylene groups with thioether groups. The parent compounds are 1,2-dithiolane and 1,3-dithiolane....
s. The inversion of polarity between R'(H)Cd+Od- and R'CLi(SR)2 is referred to as umpolung
Umpolung

Umpolung or polarity inversion in organic chemistry is the chemical modification of a functional group with the aim of the reversal of polarity of that group ...
.

See also

  • Thioketal
    Thioketal

    A thioketal in chemistry is the sulfur analogue of a ketal with one of the oxygen replaced by sulfur. A dithioketal has both oxygenes replaced by sulfur....


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