Presently researchers are seeking to convert coal tar pitch into high-value carbon fiber for use in aircraft, automobiles, sporting goods and other high-performance materials. If successful, this new carbon fiber product could increase the value of coal tar by five to 55 times of its current value, and find application in high stiffness, low-weight composites in applications such as passenger cars and light duty trucks. Due to outstanding specific strength and modulus, carbon fibers (CFs) have been used commercially in structural composite applications for high performance, light-weighting as well as ergonomics. The global market for carbon fiber is anticipated to triple in one decade and exceed 100 thousand tons in 2020 with a value of over $3 billion. While carbon fiber composites are currently used in aircraft and some racing cars, the cost of CFs is prohibitively high for many other industry sectors. The high price of CFs is directly related to the cost and yield of the precursor from which it is obtained and the cost of its conversion. a) Coal tar is an excellent precursor for carbon fiber production, yielding fibers with high modulus (stiffness). Based on your knowledge of coalification reactions, what class(es) of compounds would you expect to be relevant to fiber production? b) Extraction of coal tar – by thermal heat treatment has historically been referred to as "destructive distillation". What is the chemical rationale for use of this terminology? c) Towards sustainable materials, biopolymers are being examined for their potential as precursors for carbon fiber and related carbon-based materials. Which biopolymer would you expect to be useful and why? d) What challenge(s) would you project for using this biopolymer?