DEVELOPERS AND THEORY OF DEVELOPMENT 

 OH 



p-Hydroxyphenyl acetic acid 



323 



NH— CH2COOH 



This developer is also known as p-hydroxyphenyl glycine, or shortened to "glycine." 

 Substitution of an amino and a hydroxyl group, para to each other, into benzyl 

 alcohol or hydroxymethyl benzene, produces 



OH 



CH2OH 



p-Amino-o-hydroxybenzyl alcohol (Edinol) 



NH2 



By substituting a methyl group in the benzene nucleus, methyl benzene or toluene 

 is formed : 



CHs 



Further substitution by hydroxyl and amino groups produces 

 CH3 

 lOH 



NH: 



5- Amino-2-hydroxy toluene (p-amino-o-cresol) 



\/ 



This agent is credited as being the Monomet developing agent and also as one of the 

 original metols. 



The substitution of a single amino group in the benzene nucleus produces 



NH, 



Aminobenzene 



which is not a developer. While the substitution of a second amino group yields 

 diaminobenzene, in which, if the substituted amino groups are opposite (para) to each 

 other, the now well-known fine-grain developing agent 



NH2 



1 :4-Diaminobenzene (p-phenylenediamine) 



NH2 



is produced. If the amino groups are located adjacent (ortho) to each other, the lesser 

 known fine-grain developer 



