Appeal No. 96-2335
Application 08/213,375
examiner pursuant to 37 C.F.R. § 1.142(b).
The subject matter on appeal is directed to a method of purifying crude
N-acetyl-para-aminophenol (APAP).
All the claims stand or fall together. Claim 1 is illustrative and reads as
follows:
1. A method of purifying a crude N-acetyl-para-aminophenol (APAP)
containing color bodies or their precursors comprising forming a hot aqueous solution of
said crude APAP, and subsequently contacting said hot solution with an acid washed
adsorbent carbon which prior to said contact has been treated by contacting it with an
aqueous solution of a reducing sulfite.
The references relied upon by the examiner are:
Baron 3,748,358 Jul. 24, 1973 Kosak
3,781,354 Dec. 25, 1973
Claims 1 through 8 stand rejected under 35 U.S.C. § 103 as being
unpatentable over the combined teachings of Baron and Kosak. We reverse.
The process of claim 1 is directed to a method for purifying crude APAP. In
the manufacture of APAP, there is a tendency for color bodies and color body precursors
to form which cause the crude product to have or to develop subsequently an undesirably
colored appearance. Appellants have found that contacting a hot aqueous solution of
crude APAP with an acid washed absorbent carbon, which prior to said contact, has been
pretreated with an aqueous solution of a reducing sulfite, e.g. sodium dithionate reduces
the formation of certain impurities and produces a relatively pure decolorized APAP.
2
Page: Previous 1 2 3 4 5 6 7 Next
Last modified: November 3, 2007