Slug poison, metaldehyde

When cyclopentanecarbaldehyde is prepared, it is a colourless liquid. On standing, particularly with traces of acid, it forms the crystalline trimer. The trimer is a stable six-membered heterocycle with all substituents equatorial Acetaldehyde (ethanal) forms a liquid trimer called paraldehyde , which reverts to the monomer on distillation with catalytic acid. More interesting is metaldehyde , the common slug poison, which is an all-as tetramer (2,4,6,8-tetramethyl-l,3,5,7-tetroxocane) formed from acetaldehyde with dry HC1 at below 0°C. Metaldehyde is a white crystalline solid that has all the methyl groups pseudoequatorial, and it reverts to acetaldehyde on heating. 

Metaldehyde is widely used in the United States as a snail and slug poison. In Europe, it is also used as a solid fuel for small heaters. The pellets are often mistaken for cereal or candy. Common commercial products containing metaldehyde (2-4%) include Cory s Slug and Snail Death, Deadline for Slugs and Snails, and Bug-Geta Snail and Slug Pellets. 

Ethanal (acetaldehyde) polymerizes under the influence of acids to the cyclic trimer, paraldehyde, and a cyclic tetramer, metaldehyde. Paraldehyde has been used as a relatively nontoxic sleep-producing drug (hypnotic). Metaldehyde is used as a poison for snails and slugs, Snarol. Ketones do not appear to form stable polymers like those of aldehydes. 

Acetaldehyde boils near room temperature, and it can be handled as a liquid. Acetaldehyde is also used as a trimer (paraldehyde) and a tetramer (metaldehyde), formed from acetaldehyde under acid catalysis. Heating either of these compounds provides dry acetaldehyde. Paraldehyde is used in medicines as a sedative, and metaldehyde is used as a bait and poison for snails and slugs. 

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