Novel nicotinoid structures for covalent modification of wood: an environmentally friendly way for its protection against insects.

Martin Söftje,Dieter E Kaufmann,Rudy Plarre,Jan C Namyslo,Sophie Acker

doi:10.1039/d0ra02071k

Abstract

Timber is constantly exposed to environmental influences under outdoor conditions which limits its lifetime and usability. In order to counteract the damaging processes caused by insects, we have developed a novel and more environmentally friendly method to protect wood materials via covalent modification by organic insecticides. Starting with an important class of synthetic insecticides which are derived from the natural insecticide nicotine, various new carboxylic acid derivatives of imidacloprid were made accessible. These activated neonicotinoids were utilized for the chemical modification of wood hydroxy groups. In contrast to conventional wood preservation methods in which biocides are only physically bound to the surface for a limited time, the covalent fixation of the preservative guarantees a permanent effect against wood pests, demonstrated in standardized biological tests. Additionally, the environmental interaction caused by non-bound neonicotinoids is significantly reduced, since both, a smaller application rate is required and leaching of the active ingredient is prevented. By minimizing the pest infestation, the lifetime of the material increases while preserving the natural appearance of the material.

Highlights

The renewable natural resource wood is one of the oldest construction materials in the world and remains of great interest due to its recoverability and its good mechanical, acoustical, and thermal properties.[1]
In order to counteract the damaging processes caused by insects, we have developed a novel and more environmentally friendly method to protect wood materials via covalent modification by organic insecticides
As shown in Scheme 1 imidacloprid was synthesized from nitroguanidine (2) in a two-step synthetic pathway via imidazolidine 3 according to literature.[19,20,21,22]

Summary

Introduction

The renewable natural resource wood is one of the oldest construction materials in the world and remains of great interest due to its recoverability and its good mechanical, acoustical, and thermal properties.[1] the CO2 neutral, unprotected biomaterial suffers from signi cant environmental impacts which limit its period of use. Wood products and constructions are prone to attack or even complete destruction by insects such as termites or beetle larvae. In the subtropical and tropical regions termites are widespread and the most important pests on wood.[2,3] Whereas in moderate regions like Central to Northern Europe the house longhorn beetle and the common wood worm are economically most relevant. The primary damage to the wood is caused by the feeding larvae, whereas the grown insects cause no further damage to the wood and only pursue their reproductive instinct

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