[Toshiro]

Hi everyone . I have a question :

In that link http://www.freepatentsonline.com/5198540.html there is the " Preparation of the trityl chloride 3a by boiling 2a in toluene/acetyl chloride  "

Are they talking about the preparation of dimethoxytrityl chloride ( trityl chloride 3 a ) ?

thanks  . 

[Nick]

Hmmm...according to the patent, 3a is a trityl chloride made from 2a.  So, I looked back at 2a.  They say that they make 2a by reacting suberyl chloride (http://www.orgsyn.org/orgsyn/chemname.asp?nameID=38799) with alcohol 1a to give the "dicarboxylic acid ester" 2a.  Clearly this is a mistake because suberyl chloride is labeled 1a and it isn't an alcohol!  They mean alcohol 2b, which is 3-hydroxy-4,4-dimethoxytriphenylcarbinol.  Now, whoever wrote this patent doesn't know how to name structures but I'm almost sure that they meant to write bis(4-methoxyphenyl)(phenyl)methanol.  Think of it as trityl alcohol where two of the benzene rings have a methoxy group in the 4 position. 

NOW, if you react bis(4-methoxyphenyl)(phenyl)methanol 2b with suberyl chloride to make "dicarboxylic acid ester" 2a, that gives you a diester with this structure: (dimethoxytrityl ester)(CH₂)₅(dimethoxytrityl ester). 

I suppose it is conceivable that they made dimethyoxytrityl chloride (http://www.chemexper.com/chemicals/supplier/cas/40615-36-9.html) by reacting "dicarboxylic acid ester" 2a with acetyl chloride but it seems stupid.  I would just react bis(4-methoxyphenyl)(phenyl)methanol 2b with thionyl chloride.  There is no need to esterify 2b.

[Toshiro]

Thanks Nick , thats exactly what i thought , there is something strange in this patent 

[AWK]

1.1 Preparation of dicarboxylic acid esters (2a) from suberyl chloride (1a)

I think this is a printing error. The title shoud be;
1.1 Preparation of dicarboxylic acid esters (2a) from suberyl chloride and (1a)

where (1a) is a triphenymethyl carbinol Ph3COH