Ionic liquids (ILs) namely 1-N-butyl-3-methylimidazolium chloride ([C₄mim]⁺Cl⁻), 1-N-ethyl-3-methylimidazolium chloride ([C₂mim]⁺Cl⁻), 1-N-butyldimethylimidazolium chloride ([C₄dmim]⁺Cl⁻) and 1-N-allyl-2,3-dimethylimidazolium bromide ([Admim]⁺Br⁻) were investigated as solvent for the homogeneous acylation and carbanilation of the biopolymer cellulose. Cellulose acetates with a degree of substitution (DS) in the range from 2.5 to 3.0 are accessible within 2 h at 80 °C in a complete homogeneous procedure. The acylation of cellulose with the fatty acid chloride lauroyl chloride leads to cellulose laurates with DS from 0.34 to 1.54. The reaction starts homogeneously and continues heterogeneously. The synthesis of cellulose carbanilates succeeds in the ionic liquid [C₄mim]⁺Cl⁻ without any catalyst. The new homogeneous path gives pure cellulose carbanilates. All reactions are carried out under mild conditions, low excess of reagent and a short reaction time. The reaction media applied can be easily recycled and reused.

In the past decade, ionic liquids (ILs) have received enormous interest as solvents for cellulose. They have been studied intensively for fractionation and biorefining of lignocellulosic biomass, for dissolution of the polysaccharide, for preparation of cellulosic fibers, and in particular as reaction media for the homogeneous preparation of highly engineered polysaccharide derivatives. ILs show great potential for application on a commercial scale regarding recyclability, high dissolution power, and their broad structural diversity. However, a critical analysis reveals that these promising features are combined with serious drawbacks that need to be addressed in order to utilize ILs for the efficient synthesis of cellulose derivatives. This review presents a comprehensive overview about chemical modification of cellulose in ILs. Difficulties encountered thereby are discussed critically and current as well as future developments in this field of polysaccharide research are outlined.

Cytokines such as interferons (IFNs) activate signal transducers and activators of transcription (STATs) via phosphorylation. Histone deacetylases (HDACs) and the histone acetyltransferase (HAT) CBP dynamically regulate STAT1 acetylation. Here we show that acetylation of STAT1 counteracts IFN-induced STAT1 phosphorylation, nuclear translocation, DNA binding, and target gene expression. Biochemical and genetic experiments altering the HAT/HDAC activity ratio and STAT1 mutants reveal that a phospho-acetyl switch regulates STAT1 signaling via CBP, HDAC3, and the T-cell protein tyrosine phosphatase (TCP45). Strikingly, inhibition of STAT1 signaling via CBP-mediated acetylation is distinct from the functions of this HAT in transcriptional activation. STAT1 acetylation induces binding of TCP45, which catalyzes dephosphorylation and latency of STAT1. Our results provide a deeper understanding of the modulation of STAT1 activity. These findings reveal a new layer of physiologically relevant STAT1 regulation and suggest that a previously unidentified balance between phosphorylation and acetylation affects cytokine signaling.