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The Creation of Mustard Gas

• First developed in 1822 by French chemist César - Mansuete Despeterez who reported on the combination of sulfur dichloride and ethylene but without harmful effects
• In 1860, Frederick Guthrie synthesized the compound and noticed minor irritating effects
• In 1866, Albert Niemann was the first to notice serious health risks in mustard gas, which included blistering of the skin
• Also in 1866, Victor Meyer synthesized 2-chloroethanol with potassium sulfide (aq) and then the resulting thiodiglycol with phosphorus trichloride, which formed irritants that took a long time to both appear and heal afterward
• Finally in 1913, Hans Thacher Clarke replaced phosphorus trichloride with hydrochloric acid in the reaction used by Victor Meyer (above). Clarke was then hospitalized after a flask broke, leading to a report being sent to the German Chemical Society. This began Germany's extensive research into mustard gas and subsequent use in WWI. Clarke later realized that by not breathing into the fumes or allowing contact with the skin, the molecule was perfectly harmless.  

There are many methods of creating mustard gas:

o   Depretz method:

§  Sulfur dichloride (SCl₂) is made to react with ethylene (C₂H₄) to create sulfur mustard or mustard gas [C₄H₈Cl₂S] in the equation :

·        SCl₂ + 2 C₂H₄ → C₄H₈Cl₂S

o   Meyer method:

§  Thiodiglycol[C₄H₁₀O₂S](product of the reaction between chloroethanol and potassium sulfide) is chlorinated with phosphorus trichloride [PCl₃]to form mustard gas [C₄H₈Cl₂S]  and phosphoric acid [P(OH)₃].  It is represented by the equation:

·        3(C₄H₁₀O₂S) + 2PCl₃ → 3C₄H₈Cl₂S + 2P(OH)₃

o   Meyer-Clarke method:

§  Same as Meyer method but phosphorus trichloride [PCl₃] is replaced with hydrochloric acid [HCl] in the reaction:

·        C₄H₁₀O₂S  + 2HCl → C₄H₈Cl₂S + 2H₂O

Mustard gas was also used extensively in warfare.  More can be found about that here.  More recently, it has been developed to treat cancer.  More can be found here.

Naming Rules

• Sulfur takes numbering precedence
• Sulfur represented by 'thia' and placed before chain name 
  
• In general:

               [groups] ─ [location of S in main chain / #] ─ [thia'chain name']

Ex: 

OR... 

• Since the sulfur atom is in the centre / the molecule is symmetrical, the main chain can be numbered in either of the two possibilities
• NAME: 3 ─ thiapentane

Ex:

  NOT... 

• This molecule is very similar to the previous example.  However, there is only one numbering possibility.
• You must first look where the S atom is.  Since it is in the centre, numbering again works both ways.
• You must next look at the position of the groups and number the main chain according to lowest sums.  In this example, the group numbering could be 2 or 4.  Since 2 is lower, that is how we will number.
• NAME: 2 ─ methyl ─ 3 ─ thiapentane

Ex:

  NOT... 

• In this case, the molecule is not symmetrical and sulfur must be numbered like this.
• Again, sulfur takes precedence over the groups 
• NAME: 3 ─ methyl ─ 2 ─ thiabutane

Ex:

  OR... 

• In this example, sulfur is in the middle, so numbering is the same either ways
• The chlorine is treated like a group and has the same numbering both ways
• Thus, this molecule can be numbered either way
• NAME: 1,5 ─ dichloro ─ 3 ─ thiapentane (MUSTARD GAS)