Xylyl bromide



Xylyl bromide, also known as methylbenzyl bromide or T-stoff, is a poisonous organic chemical compound with the molecular formula C8H9Br, formerly used as a tear gas. Physically it is a colourless liquid (melting point 21 °C) with a pleasant aromatic odour.

Use as a weapon
Xylyl bromide is highly toxic, irritant and lachrymatory, and has been incorporated in chemical weapons since the early months of World War I. Some commentators say the first use was in August 1914, when the French attacked German soldiers with tear gas grenades, but the agent used in that incident was more likely to be ethyl bromoacetate, which the French had tested before the war.

The first extensive use of xylyl bromide was the firing by German forces of 18,000 "T-shells" at Russian positions in the Battle of Bolimów in January 1915. The shells were modified 15 cm (6 inch) artillery shells containing an explosive charge and c. 3 kg (7 lb) xylyl bromide. The attack was a complete failure because the winter weather was too cold to permit an effective aerosol, and the agent was either blown back towards the German lines, fell harmlessly to the ground, or was insufficiently concentrated to cause damage. A similar attack at Nieuwpoort in March 1915 was also unsuccessful. Nevertheless, because of its ease of manufacture xylyl bromide was widely used in World War I, in particular as a component of the Germans' Weisskreuz (white cross) mixture.

Structural isomers
The three isomers, collectively referred to by CAS registry number, are:


 * CAS RN : o-xylyl bromide (2-methylbenzyl bromide, systematic name 1-bromomethyl-2-methylbenzene) (NIST record)
 * CAS RN : m-xylyl bromide (3-methylbenzyl bromide, systematic name 1-bromomethyl-3-methylbenzene) (NIST record)
 * CAS RN : p-xylyl bromide (4-methylbenzyl bromide, systematic name 1-bromomethyl-4-methylbenzene) (NIST record)

In the absence of clarification, the name "xylyl bromide" may refer to any one of these isomers or a mixture of all three. This reflects the same ambiguity inherint in the name xylene, from which xylyl bromide may be prepared.