A<unk> in chemistry is any neutral chemical compound with a positively charged cationic functional group such as an ammonium ion or phosphonium ion (generally: onium ions) which bears no hydrogen atom and with a negatively charged functional group such as a carboxylate group which may not be adjacent to the cationic site. Historically the term was reserved for trimethylglycine only.
Phosphonium<unk>  are intermediates in the Wittig reaction.
In biological systems, many<unk>  serve as organic osmolytes, substances synthesised or taken up from the environment by cells for protection against osmotic stress, drought, high salinity or high temperature. Intracellular accumulation of<unk> , non-perturbing to enzyme function, protein structure and membrane integrity, permits water retention in cells, thus protecting from the effects of dehydration.  It is also a methyl donor of increasing significance.
Betaines
Benzocaine 
Opiate
Nicotine
Nicotine 
Articaine
Benzyl
Benzidine