Georg Wittig, 90, the German scientist who shared the 1979 Nobel Prize in chemistry for developing a method of synthesizing compounds widely used in the pharmaceutical industry, died Wednesday in Heidelberg, West Germany.

Dr. Wittig was an emeritus professor at Heidelberg University. The cause of his death was not disclosed in a statement issued by the university.

The Nobel Prize committee honored Dr. Wittig for what his colleagues and scientific heirs in organic chemistry call the Wittig synthesis, or Wittig reaction. (Organic chemistry deals with compounds composed of rings or chains of carbon atoms.)

The synthesis that Dr. Wittig first demonstrated in 1954 is a means of causing certain phosphorus compounds to react with certain carbon compounds to produce a third class of organic compounds known as olefins or alkenes.

The properties of many of the complicated organic molecules that are valuable as pesticides or in medicine depend not only on the nature and number of the atoms that make them up, but also on the way these atoms are arranged in space and how they are joined together.

Dr. Wittig's synthesis permitted more rapid production of complex compounds. It also made possible the duplication in the laboratory of both the composition and the molecular structure of certain important chemicals that appear in nature.

Among the compounds synthesized through the Wittig reaction is one form of Vitamin D.

Dr. Wittig shared the 1979 Nobel Prize with Dr. Herbert Charles Brown of Purdue University, who specialized in organic reactions involving boron compounds.

Dr. Wittig was born in Berlin, June 16, 1897, and studied at Kassel and Marburg universities. He taught at Marburg from 1926 to 1932, and at other academic institutions, including Tubingen, before becoming a professor at Heidelberg in 1956. He became professor emeritus in 1967.

Long after his reaction had become a standard part of the curriculum in college-level introductory organic chemistry courses, Dr. Wittig continued working on phosphorus chemistry in his private laboratory at home.

In 1979, the year he won the Nobel Prize, he repeated the advice he gave to young chemists.

"Never give up," he said, "always challenge the impossible."

THE REV. FRANK LESLIE FADNER, 76, a retired regent of the Georgetown University School of Languages and Linguistics, died of congestive heart failure Aug. 26 at Georgetown University Hospital. He lived in Washington.

Fr. Fadner, a member of the Society of Jesus, was born in Neenah, Wis. He moved to the Washington area in 1929, and graduated from the Georgetown University School of Foreign Service in 1933. He graduated from Woodstock College in Maryland in 1943 and was ordained a priest.

From 1944 to 1946, he taught history and languages at the University of Scranton in Pennsylvania. In the late 1940s he earned a doctorate in Russian history at the University of London.

Fr. Fadner returned to Washington in 1949 and joined the faculty at Georgetown, where he taught Russian history until 1955. He was regent of the Edmund A. Walsh School of Foreign Service until 1962, when he was named regent of the university's School of Languages and Linguistics. He retired in 1977.

He was a former member of the Georgetown University board of directors.

His books include, "Seventy Years of Pan-Slavism: Karazin to Danilevskii, 1800-1870," published in 1962.

Survivors include one sister, Georgian Murphy of Brookfield, Wis.

ANNE CHAPMAN TREMEARNE, 59, a Washington native who taught photography and music in Massachusetts, died of a heart ailment Aug. 23 at a clinic in Burlington, Mass. She lived in Bedford, Mass.

Miss Tremearne graduated from Woodrow Wilson High School here and attended the Peabody Conservatory of Music in Baltimore.

She lived in Baltimore from 1955 to 1969, and then in Guilford, Conn., until 1982, when she moved to Massachusetts.

Survivors include her mother, Margaret Chapman Tremearne of Kensington, and one sister, Jane Zuke of Adelphi.

HELEN S. WINKLER, 78, a retired stenographer with the National Institutes of Health and a member of Chevy Chase Presbyterian Church, died of cancer Aug. 23 at her home in Chevy Chase.

Miss Winkler was born in Chevy Chase and graduated from Rockville High School.

She began her government career in the 1930s with the Home Owners' Loan Corp. She transferred to the Veterans Administration in the late 1930s and worked there until the early 1950s, when she joined NIH. She retired in 1974.

Survivors include two sisters, Margaret W. Thomas of Washington and Barbara L. Winkler of Chevy Chase, and one brother, Fred B. Winkler, also of Chevy Chase.

DENNIS A. McGRAW, 77, a retired official with the Internal Revenue Service, died of cardiac arrest Aug. 20 at Holy Cross Hospital. He lived in Hyattsville.

Mr. McGraw was born in Frostburg, Md., and graduated from Strayer Business College. He moved to the Washington area in 1940 and went to work for the predecessor of the Internal Revenue Service. He retired in 1973 as assistant chief of the agency's individual income-tax section.

During World War II, Mr. McGraw served in the Army in Europe and was awarded the Bronze Star and the Purple Heart.

Survivors include his wife, Mary Devlin McGraw of Hyattsville; one daughter, Catherine Bahl of Conakry, Guinea; three sisters, Margaret McGraw of Lonaconing, Md., Evelyn Paone of Revere, Mass., and Kathleen Herrington of Winchester, Ky., and two grandchildren.

HORACE N. McLILLY, 83, a retired business manager of the Washington Afro-American newspaper, died of cancer Aug. 18 at Washington Hospital Center.

Mr. McLilly, a resident of Washington, was born in Gainesville, Fla. He moved to Atlanta as a young man and graduated from Clark College and Gammon Theological Seminary there.

In 1942, he moved to Washington and went to work on the Afro-American as circulation manager. He later became business manager and held that post until he retired in 1982.

Mr. McLilly was a treasurer of Ebenezer United Methodist Church and a member of the Clark College Alumni Association, Omega Psi Phi fraternity and the Benning Ridge Civic Association.

His wife, Angelyn Tatum McLilly, whom he married on Christmas Day, 1937, died in 1984.

There are no immediate survivors.

GRACE ALBERTA BROWN, 93, a retired statistician with the marketing division of the Department of Agriculture, died of cardiac arrest Aug. 22 at the Magnolia Gardens Nursing Home in Lanham.

Mrs. Brown, who lived in Lanham, was born in Coin, Iowa. She grew up in the Washington area and graduated from Eastern High School. She joined the Agriculture Department in 1912 and transferred to the Social Security Administration in 1936. She returned to Agriculture in 1942 and retired there in 1964.

She had received Agriculture's outstanding service award.

Mrs. Brown was a member of Brightwood Park United Methodist Church in Washington, where she was a past president of the Women's Society of Christian Service.

Her husband, Charles R. Brown, died in 1940. Survivors include one son, Charles R. Brown Jr. of Lanham; two daughters, Lucile G. Dant of Takoma Park and Marjorie A. Zapf of Ward, Colo.; one sister, Lucile A. Reese of Washington; eight grandchildren; 21 great-grandchildren, and one great-great-grandchild.

ROY J. ROBISON, 69, a retired Navy captain who became deputy director of the continuing engineering education program at George Washington University, died of cancer Aug. 25 at the Crystal City Nursing Center in Arlington.

Capt. Robison, a resident of McLean who had lived in the Washington area since 1966, was born in Newark, Ohio. He graduated from the U.S. Naval Academy at Annapolis in the class of 1942, and later from the Naval War College at Newport, R.I.

During World War II, he served on the battleship USS Washington and then went into submarines. He finished the war aboard the submarine Pompon in the Pacific.

Later in his career he was captain of the submarines Stickleback and Volador and commanded Submarine Division 51, based at San Diego. Other assignments took him to Norfolk and Washington, where he served in the Navy Department's Bureau of Personnel and the Naval Ship Systems Command.

He was in the Office of the Inspector General of the Navy when he retired from the service in 1972. He worked during the next eight years at George Washington University, and retired a second time in 1980.

Capt. Robison's military decorations included the Legion of Merit.

He was a member of the Naval Academy Alumni Association and St. John's Catholic Church in McLean.

Survivors include his wife, the former Joyce Parkinson, of McLean; four children, Thomas Robison of Albuquerque, Army Maj. James P. Robison of Centreville, Katherine Keeter of Wilmington, N.C., and Mary Robison of Falls Church; one brother, Frank Robison of Newark, and six grandchildren.