The Foreign Office said the chemical "B precursors" will be shipped to a British port with suitable off- loading equipment before transfer to a commercial site for incineration.
A spokesman stressed the chemicals, "used in the pharmaceutical industry", become toxic only when combined with an "A precursor" to make a nerve agent.
"To eliminate this risk, the A and B precursors will be removed from Syria separately," the spokesman said.
"It is important to stress these are chemicals, not chemical weapons. They do not contain explosives. The chemicals will be sealed in industrial containers to international standards and under the supervision of OPCW [Organisation for the Prohibition of Chemical Weapons] inspectors."
The British contribution is part of an international effort to dispose of Syria's chemical stockpile following the agreement by Mr Assad to give up his weapons in a deal brokered by the United States and Russia.
The Government is providing a Royal Navy warship to help protect the Danish and Norwegian cargo vessels which will ship the entire stockpile out of Syria as they are sailing through international waters.
It is also providing specialist equipment to the United States to assist in the treatment of the most sensitive chemicals before they are finally destroyed.
"The international mission to destroy Syria's chemical weapons programme is essential to ensure that Assad can never again use these horrific weapons to murder his own people," the Foreign Office spokesman said.
Shadow foreign secretary Douglas Alexander said: "It is right that Britain uses its world-class facilities to make this contribution to destroying Syria's chemical stockpile. We welcome that the Government has given assurances it will implement the tightest safeguards."