diff --git a/applcn/chemic.g.elly b/applcn/chemic.g.elly
index b747eeb..44c7a8b 100644
--- a/applcn/chemic.g.elly
+++ b/applcn/chemic.g.elly
@@ -1,5 +1,5 @@
 # parsing of chemical names in text
-# chemical.g.elly
+# chemic.g.elly
 
 #
 # basic parsing
@@ -113,6 +113,33 @@ __
 g:CHEM->RNGX CHEM
 __
 
+g:LOCN->LOCN QUAL
+__
+
+p:prej
+_
+  left
+  delete 1 >
+  split
+  right
+  back
+  var ch=
+  extract ch <
+  if ~ch=+
+    insert < ch
+    end
+  merge
+__
+
+g:CHEM->PRFX CHEM
+_
+  (prej)
+__
+g:CHEM->PRFX UNKN
+_
+  (prej)
+__
+
 #
 # for locant structural description
 
diff --git a/applcn/chemic.p.elly b/applcn/chemic.p.elly
index dd6066a..51433c7 100644
--- a/applcn/chemic.p.elly
+++ b/applcn/chemic.p.elly
@@ -22,3 +22,7 @@
 0 !$  ATOM -1
 
 0 -#$ ATID -1
+
+0 (#!) QUAL -1
+
+0 &@+ PRFX -1
diff --git a/applcn/chemic.ptl.elly b/applcn/chemic.ptl.elly
new file mode 100644
index 0000000..8c16a24
--- /dev/null
+++ b/applcn/chemic.ptl.elly
@@ -0,0 +1,6 @@
+# parsing of chemical names in text
+# chemic.ptl.elly
+
+thio 1 0 .
++per  1 0 .
++oxy  1 0 .
diff --git a/applcn/chemic.stl.elly b/applcn/chemic.stl.elly
index 74cc795..0490452 100644
--- a/applcn/chemic.stl.elly
+++ b/applcn/chemic.stl.elly
@@ -10,8 +10,10 @@ diene    1 0 0
 ethyl    1 0 0
 indene   1 0 0
 methyl   1 0 0
+one      1 0 0
 oxide    1 0 0
 sulfate  1 0 0
 sulfide  1 0 0
+thioic   1 0 0
 
 naphthalene 1 0 0
diff --git a/applcn/chemic.v.elly b/applcn/chemic.v.elly
index 426d625..4293288 100644
--- a/applcn/chemic.v.elly
+++ b/applcn/chemic.v.elly
@@ -18,13 +18,16 @@ acet    : ROOT
 chloro  : ROOT
 dimethano : ROOT
 methano : ROOT
+naphthalen : ROOT
 propa   : ROOT
 
 acetate  : CHEM
 acetic   : CHEM
 acid     : CHEM
 benzene  : CHEM
+butane   : CHEM
 chloride : CHEM
+diphosphoric : CHEM
 ethyl    : CHEM
 heptane  : CHEM
 idene    : CHEM
diff --git a/chemic.main.key b/chemic.main.key
index ba14c34..6c02ab4 100644
--- a/chemic.main.key
+++ b/chemic.main.key
@@ -10,3 +10,6 @@
  uu 〖bicyclo[3.2.0]heptane〗!
  uu 〖benzo[1′′,2′′:3,4;5′′,4′′:3′,4′]dicyclobuta[1,2-a:1′,2′-a′]diindene〗!
  uu 〖4-(2-naphthalenyl)-benzoic acid〗!
+ zzz 〖butane (dithioic) acid〗!
+ zzz 〖1(2h)-naphthalenone〗!
+ zzz 〖thioperoxydiphosphoric acid〗!
diff --git a/chemic.main.txt b/chemic.main.txt
index bdc59ec..d19b934 100644
--- a/chemic.main.txt
+++ b/chemic.main.txt
@@ -10,3 +10,6 @@ uu N-2-naphthalenyl-acetamide !
 uu bicyclo[3.2.0]heptane !
 uu benzo[1′′,2′′:3,4;5′′,4′′:3′,4′]dicyclobuta[1,2-a:1′,2′-a′]diindene !
 uu 4-(2-naphthalenyl)-benzoic acid !
+zzz butane(dithioic) acid !
+zzz 1(2H)-naphthalenone !
+zzz thioperoxydiphosphoric acid !