Visweswara Rao Durvasula

46124004, Sep 16, 1986

Dec 20, 1985

6/811797

Visweswara R. Durvasula - Cheshire CT

The Dow Chemical Company - Midland MI

C07C 49784

568333

A method is described for autoxidizing a novel class of bis(ortho dialkyl-phenoxy)benzophenones directly to their corresponding dianhydrides. The method comprises autoxidizing the benzophenones in a solution of an aliphatic monocarboxylic acid having 3 to 8 carbon atoms with oxygen in the presence of a heavy metal oxidation catalyst and a promoter at a temperature of at least about 120. degree. C. to form the dianhydride. The dianhydrides are used in the preparation of organic high temperature polymers such as polyetherimides.

45994455, Jul 8, 1986

Sep 21, 1984

6/652922

Visweswara R. Durvasula - Cheshire CT

The Dow Chemical Company - Midland MI

C07C 5109
C07D30788

562419

A method is described for autoxidizing particular ortho-dialkyl substituted aromatic compounds using a particular type of solvent which gives rise to the formation of 3-alkanoyloxyphthalide compounds, some of which are novel. The phthalides in turn are ionically oxidized to their corresponding aromatic polycarboxylic acids. Combination of the two methods provides a means for converting ortho dialkyl substituted aromatic compounds directly to the corresponding polycarboxylic acids in higher yields and at generally lower overall temperatures and reaction conditions compared to prior art methods. Polycarboxylic acids so obtained are known to be useful in the preparation of alkyds, polyesters, and the like, and, particularly, in the formation of the corresponding acid anhydrides which are used in the preparation of organic high temperature polymers such as polyamides, polyamideimides, and polyimides.

51030420, Apr 7, 1992

May 23, 1990

7/527999

Visweswara R. Durvasula - Lake Jackson TX
Franz J. Luxem - Clute TX

The Dow Chemical Company - Midland MI

C07C 6966

560189

Polyethers having terminal allyl unsaturation are subject to hydrogenolysis by reaction with a hydrogen donor in the presence of a n-allyl complex forming catalyst. The product polyethers have extremely low levels of unsaturation, and thus are useful in preparing polyurethanes having improved properties and processing.

49609505, Oct 2, 1990

Mar 28, 1988

7/173905

Visweswara R. Durvasula - Cheshire CT

The Dow Chemical Company - Midland MI

C07C 4114

568587

Disclosed is a novel process for effecting an ether interchange reaction by heating together in the presence of a basic catalyst, a nitroaromatic ether or thioether and an organic compound containing at least one hydroxyl or mercapto group. The novelty resides particularly in carrying out the interchange in an inert solvent while sparging the heated reactants thereby to remove at least a portion of solvent along with an evolving alcohol or thiol. The process is particularly adapted to the capping of organic polyols with nitroaromatic ether groups. The capped products are useful as intermediates for the preparation of high molecular weight polyamines which in turn find utility in various polymer applications.

45770344, Mar 18, 1986

Feb 14, 1985

6/701835

Visweswara R. Durvasula - Cheshire CT

The Dow Chemical Company - Midland MI

C07D30789

549241

A method is described for autoxidizing a novel class of bis(ortho dialkyl-phenoxy)benzophenones directly to their corresponding dianhydrides. The method comprises autoxidizing the benzophenones in a solution of an aliphatic monocarboxylic acid having 3 to 8 carbon atoms with oxygen in the presence of a heavy metal oxidation catalyst and a promoter at a temperature of at least about 120. degree. C. to form the dianhydride. The dianhydrides are used in the preparation of organic high temperature polymers such as polyetherimides.

48474169, Jul 11, 1989

Apr 6, 1987

7/035121

Visweswara R. Durvasula - Cheshire CT
Fred A. Stuber - North Haven CT

The Dow Chemical Company - Midland MI

C07C 9140
C07C14942
C08G 1800
C08G 1818

564443

Disclosed is a class of poly(aminoaromatic) compounds (I) obtained by capping polymeric polyols or polythiols with aromatic amine groups wherein the latter groups are linked by --O--or --S--to the polyol (polythiol) residues. Also disclosed are the precursor poly(nitroaromatic) compounds (II) from which the compounds (I) are derived. The polyamines are characterized by amine reactivities in respect of isocyanate polyaddition reactions which allows for polymer reaction rates that are intermediate of prior art related polyamine compounds. Accordingly, the compounds (I) find their prime utility in the formation of synthetic resins containing polyurea linkages.

50792750, Jan 7, 1992

Apr 10, 1989

7/335352

Visweswara R. Durvasula - Cheshire CT
Fred A. Stuber - North Haven CT

The Dow Chemical Company - Midland MI

C08G 1832

521163

Disclosed is a class of poly(aminoaromatic) compounds (I) obtained by capping polymeric polyols or polythiols iwth aromatic amine groups wherein the latter groups are linked by --O-- or --S-- to the polyol (polythiol) residues. Also disclosed are the precursor poly(nitroaromatic) compounds (II) from which the compounds (I) are derived. The polyamines are characterized by amine reactivities in respect of isocyanate polyaddition reactions which allows for polymer reaction rates that are intermediate of prior art related polyamine compounds. Accordingly, the compounds (I) find their prime utility in the formation of synthetic resins containing polyurea linkages.

45269840, Jul 2, 1985

Oct 29, 1984

6/665905

Visweswara R. Durvasula - Cheshire CT

The Upjohn Company - Kalamazoo MI

C07D30789

549241

A method is described for autoxidizing ortho-dialkyl substituted aromatic ethers directly to their corresponding carboxylic acid anhydrides. The method comprises autoxidizing the ethers in a first step in a solution of an aliphatic monocarboxylic acid having 2 to 8 carbon atoms to form a partially oxidized reaction mixture. The autoxidation of the partially oxidized mixture is continued in a second step after the addition of an anhydride of an aliphatic monocarboxylic acid having 3 to 8 carbon atoms and at a temperature of at least 130. degree. C. to form said anhydrides. The anhydrides are used in the preparation of organic high temperature polymers such as polyamideimides, polyimides, polyetherimides, and polyetherimideamides.