A hydrophilic polymer derivative having a cyclic benzylidene acetal linker represented by the following formula (1): ##STR00001##
wherein R.sup.1 and R.sup.6 are each independently a hydrogen atom or a hydrocarbon group; R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are each independently an electron-withdrawing or electron-donating substituent or a hydrogen atom; X.sup.1 is a chemically reactive functional group; P is a hydrophilic polymer; s is 1 or 2, t is 0 or 1, and s+t is 1 or 2; w is an integer of 1 to 8; and Z.sup.1 and Z.sup.2 are each independently a selected divalent spacer.

A biodegradable polyethylene glycol derivative in which a polyethylene glycol chain is linked by an acetal linker capable of accurately controlling the hydrolysis rate under different pH environments in the living body, and whose division rate into a polyethylene glycol chain of low molecular weight in the living body can be accurately controlled. The biodegradable polyethylene glycol derivative is represented by formula (1) or formula (2) as described.

A polyphenylene ether bismaleimide resin, a method for manufacturing the same, and a resin composition are provided. The polyphenylene ether bismaleimide (PPE-BMI) resin is obtained by a condensation reaction with a maleic anhydride and a primary amine compound as reactants. The primary amine compound is a polyphenylene ether diamine.

The present invention provides a method for producing a hetero-type monodisperse polyethylene glycol, which includes a step (A) of carrying out a nucleophilic substitution reaction between a compound of the formula (2) and a compound of the formula (3) so as to satisfy the requirement of the expression (F1) to obtain a compound of the formula (4), a step (B) of carrying out the Michaels addition reaction of a compound of the formula (5) to the compound of the formula (4) at a temperature condition of 10° C. or lower to obtain a compound of the formula (6), a step (C) of detritylating or debenzylating the compound of the formula (6) to obtain a reaction product containing a compound of the formula (7), a step (D) of purifying the compound of formula (7) from the reaction product, a step (E) of reacting the compound of the formula (7) with phthalimide and performing dephthalimidation to obtain a compound of the formula (8), and a step (F) of subjecting the compound of formula (8) to an acid hydrolysis treatment to obtain a compound represented by the formula (1).

A polyphenylene ether bismaleimide resin, a method for manufacturing the same, and a resin composition are provided. The polyphenylene ether bismaleimide (PPE-BMI) resin is obtained by a condensation reaction with a maleic anhydride and a primary amine compound as reactants. The primary amine compound is a polyphenylene ether diamine.

The present invention provides a method for producing a maleimide polyethylene glycol lipid, and the method includes a reaction step of deprotecting a maleimide polyethylene glycol lipid having a protective group by heating the maleimide polyethylene glycol lipid having a protective group in a solvent in the presence of silica gel. According to the present invention, a production method of preventing deterioration of a maleimide group and improving a maleimidation rate can be provided.

A hydrophilic polymer derivative having a cyclic benzylidene acetal linker represented by the following formula (1):

##STR00001##

wherein R.sup.1 and R.sup.6 are each independently a hydrogen atom or a hydrocarbon group; R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are each independently an electron-withdrawing or electron-donating substituent or a hydrogen atom; X.sup.1 is a chemically reactive functional group; P is a hydrophilic polymer; s is 1 or 2, t is 0 or 1, and s+t is 1 or 2; w is an integer of 1 to 8; and Z.sup.1 and Z.sup.2 are each independently a selected divalent spacer.

A biodegradable polyethylene glycol derivative in which a polyethylene glycol chain is linked by an acetal linker capable of accurately controlling the hydrolysis rate under different pH environments in the living body, and whose division rate into a polyethylene glycol chain of low molecular weight in the living body can be accurately controlled. The biodegradable polyethylene glycol derivative is represented by formula (1) or formula (2) as described.

A method for producing a hetero-type monodisperse polyethylene glycol, which includes (A) carrying out a nucleophilic substitution reaction between a compound of formula (2) and a compound of formula (3) so as to satisfy expression (F1) to obtain a compound of formula (4), (B) of carrying out a Michaels addition reaction of a compound of formula (5) to the compound of formula (4) at a temperature condition of 10? C. or lower to obtain a compound of formula (6), (C) detritylating or debenzylating the compound of the formula (6) to obtain a reaction product containing a compound of formula (7), (D) purifying the compound of formula (7) from the reaction product, (E) reacting the compound of formula (7) with phthalimide and performing dephthalimidation to obtain a compound of formula (8), and (F) subjecting the compound of formula (8) to an acid hydrolysis treatment to obtain a compound represented by formula (1).

The present invention relates to a composition containing a particulate solid, a polar or non-polar organic medium, and a polymer chain having at least one non-fused aromatic imide pendant group. The invention further provides compositions for coatings, inks, toners, plastic materials (such as thermoplastics), plasticisers, plastisols, crude grinding and flush.